Administration Of rIL-2 Research Articles

Dose distribution of low-dose subcutaneous recombinant interleukin-2 affects the secondary release of interferon-gamma in vivo.

Human recombinant interleukin-2 (rIL-2) induced interferon-gamma (IFN-gamma) release in vivo was studied in 16 renal cell carcinoma patients treated with low-dose s.c. rIL-2. The s.c. administration of rIL-2 resulted in a significant increase in circulating IFN-gamma in all patients within 6 to 8 hours as measured by enzyme-linked immunosorbent assay (ELISA). Total IFN-gamma release, as expressed by the area under the concentration curve (AUC), and IFN-gamma serum peaks following repetitive s.c. rIL-2 injection showed a direct dose distribution dependancy, whereby significantly higher levels of secondary IFN-gamma were achieved in patients treated with 10 million IU rIL-2/m2 q 12 hours when compared with patients treated with 20 million IU rIL-2/m2 q 24 hours. IFN-gamma release was suppressed significantly in one patient who had been pretreated with corticosteroids, while prior immunotherapy with rIL-2 had no measurable effect on secondary IFN-gamma release in this study. Cumulative secondary IFN-gamma secretion, as expressed by the AUC, and IFN-gamma serum peak concentrations in response to s.c. rIL-2 did not correlate with response to therapy or survival of rIL-2 treated renal cell carcinoma patients.

Inhibitory effect of metastasis by combined administration with interleukin-2 and sizofiran, a single glucan--immunohistochemical study.

Innovations in methods of combined administration with other BRM or chemotherapeutic drugs have been discussed. We have reported that combined administration with recombinant interleukin-2 (rIL-2) and sizofiran (SPG) is effective in prolonging survival time of C57BL/6 mice intraperitoneally inoculated with EL-4 lymphoma. The immunomechanisms of the combined administration were clarified investigating the intraperitoneal cell population in the primary tumor site, especially the tumor infiltrating lymphocyte (TIL) quantitatively. In the present study, to clarify the antitumor effects of combined administration with rIL-2 and SPG on the metastatic sites, the immunomechanisms of the suppressive effects of combined administration on the metastasis were studied in EL-4 lymphoma cells intraperitoneally transplanted to mice. Inasmuch as EL-4 lymphoma shows rapid hepatosplenic metastasis, we studied the metastatic foci in the liver and the spleen semiquantitatively in investigating the histopathological and immunohistochemical findings of the metastatic foci, especially the TIL. The metastatic foci were stained by hematoxylin-eosin (HE) and monoclonal antibodies (L3T4, Lyt2, asialo GM1, Mac-1, and Ia). The combined administration resulted in: 1) fewer infiltrating tumor cells, 2) more lymphocytic infiltration, and 3) more antitumor effector cells (cytotoxic T cells: Lyt2 and natural killer cells: asialo GM1), macrophages (Mac-1), helper T cells (L3T4), and cells with MHC-class-II antigen (Ia) than did administration of rIL-2 alone or SPG alone, or no administration of these two at all. Combined administration with rIL-2 and SPG appears to activate antitumor-immune response at the metastatic site more effectively than when either agent is administered alone.

Augmentation of antitumor effect by combined administration with interleukin-2 and sizofiran, a single glucan, on murine EL-4 lymphoma.

The antitumor effect of the combined administration with recombinant human interleukin-2 (rIL-2) and sizofiran (SPG), a single glucan of Shizophyllum commune Fries, was studied in vivo in C57BL/6 mice intraperitoneally inoculated with EL-4 lymphoma. The effect was evaluated by a) comparing the survival time of the mice, b) analysis of the intraperitoneal cell population in Giemsa-stained specimens, c) surface marker analysis of peritoneal exudative cells with flow cytometry, d) cytotoxic assay of cells against EL-4 and Yac-1 lymphoma, and e) elimination of some cell populations by monoclonal antibodies, to identify the antitumor-effector cells showing cytotoxic activity. The survival of mice given both rIL-2 and SPG was significantly longer than the control mice or those given SPG alone or rIL-2 alone. It was demonstrated that the administration of SPG and/or rIL-2 to the EL-4 lymphoma-bearing mice activated immune-response cells in the peritoneal cavity such as T lymphocytes, NK cells, or macrophages, which might be effective in reducing lymphoma cells. The combination of rIL-2 and SPG administration appears to activate the antitumor-immune response at the tumor site more effectively than when either agent was administered alone.

Interleukin-12 prevents antigen-induced eosinophil recruitment into mouse airways.

Interleukin-12 (IL-12) is a key cytokine that promotes Th1-type cell-mediated immunity and inhibits Th2-type responses. We have previously shown that antigen-induced eosinophil recruitment into the airways of sensitized mice is mediated by Th2-type CD4+ T cells that produce IL-5. Therefore, to determine whether IL-12 regulates antigen-induced eosinophil recruitment into the airways, we studied the effect of recombinant murine IL-12 on antigen-induced eosinophil infiltration into the tracheas of sensitized mice, and also the effect of IL-12 on IL-5 and interferon-gamma (IFN-gamma) levels in bronchoalveolar lavage fluid (BALF) from the mice. The intraperitoneal administration of recombinant IL-12 (rIL-12) inhibited antigen-induced eosinophil infiltration into the mouse trachea in a dose-dependent manner. The administration of rIL-12 suppressed IL-5 levels but enhanced IFN-gamma levels in the BALF of the mice after antigen inhalation. The administration of rIL-12 also decreased in vitro antigen-induced IL-4 and IL-5 production, but not IFN-gamma production, in spleen cells of the mice. Furthermore, pretreatment with anti-IFN-gamma monoclonal antibody prevented the IL-12 inhibition of antigen-induced eosinophil infiltration into the tracheas of the mice. These results indicate that IL-12 downregulates antigen-induced eosinophil recruitment into the airways by inhibiting IL-5 production in sensitized animals.

Immunopharmacology and cytokine production of a low-dose schedule of intraperitoneally administered human recombinant interleukin-2 in patients with advanced epithelial ovarian carcinoma.

We determined in the peritoneal cavity (p.c.) of epithelial ovarian carcinoma patients during a 4-day treatment cycle of low-dose recombinant human interleukin-2 (rIL-2): (a) pharmacokinetics of IL-2, (b) endogenous cytokine production, and (c) numbers and percentages of peritoneal exudate lymphocytes. We administered 6 x 10(5) IU/m2 of rIL-2 (0.03 mg/m2 Proleukin rIL-2) intraperitoneally (i.p.) over 30 min on each of 4 days. One and one-half liters of D5 0.25 NS was injected i.p. before each rIL-2 infusion. Multiple peritoneal fluid samples were obtained from each of four patients on day 1 and day 4 for detection of IL-2, endogenous cytokines, and soluble IL-2 receptor (IL-2R-alpha). IL-2 concentrations in the peritoneal fluid were determined by bioassay and interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, IL-10, transforming growth factor (TGF)-beta 2, and sIL-2R-alpha by enzyme-linked immunosorbent assay. Numbers of cells per microliter and lymphocyte subpopulation percentages after staining with a panel of monoclonal antibodies were determined on day 1, day 4, and subsequent off-treatment days. IL-2 disappearance in the p.c. was well described by a pharmacokinetic model having constant-rate infusion and biexponential disposition. About 90% of the IL-2 disappearance occurred during the beta-phase, during which IL-2 concentrations were sustained at approximately 10-30 ng/ml (day 1 and day 4) and the median t1/2 beta was 21.5 and 9.2 h on days 1 and 4, respectively. In four of four patients, p.c. production of IL-10 was observed on day 1 and day 4 (maximum 387 pg/ml). Maximum levels of IFN-gamma and sIL-2R-alpha were observed on day 4. (IFN-gamma 217 pg/ml; sIL2-R-alpha: 3486 U/ml). No increases in TNF-alpha or TGF-beta 2 were observed. Large increases in p.c. CD3+, CD4+, CD8+, CD16+, and CD56+ cells were observed. We conclude that biologically active levels of IL-2 are generated in p.c. fluids after i.p. administration of rIL-2 at 0.03 mg/m2.

Induction of graft versus leukemia effects by cell-mediated lymphokine-activated immunotherapy after syngeneic bone marrow transplantation in murine B cell leukemia.

The feasibility of inducing graft versus leukemia (GVL) effects with allogeneic T cells in recipients of autologous bone marrow transplantation (BMT) was studied in a murine model (BCL 1) of human B cell leukemia/ lymphoma. Allogeneic cell therapy, induced by infusion with peripheral blood lymphocytes, a mixture of allogeneic spleen and lymph node cells and allogeneic activated cell therapy, induced by in vitro recombinant-interleukin-2(rIL-2)-activated allogeneic bone marrow cells in tumor-bearing mice, prevented disease development in adoptive BALB/c recipients. Concomitant in vivo activation of allogeneic lymphocytes with rIL-2 suppressed even more effectively the development of leukemia in secondary adoptive recipients of spleen cells obtained from treated mice. In contrast, in vivo administration of rIL-2 after syngeneic BMT, with or without equal numbers of syngeneic lymphocytes, led to disease development in secondary recipients. Our data suggest that effective cell therapy can be achieved after SBMT by allogeneic but not syngeneic lymphocytes and that anti-leukemic effects induced by allogeneic lymphocytes can be further enhanced by in vitro or in vivo activation of allogeneic effector cells with rIL-2. Therefore, cell therapy by allogeneic lymphocytes following autologous BMT could become an effective method for inducing GVL-like effects on minimal residual disease provided that graft versus host disease can be prevented or adequately controlled.

Antitumor and antimetastatic effects of interleukin 12.

Interleukin 12 (IL-12) has a pivotal role in controlling cell-mediated immunity through a number of important biological activities, such as secretion of interferon-gamma (IFN-gamma). In this review, we report our recent results regarding the antitumor and antimetastatic effects of IL-12. Five intraperitoneal injections of recombinant IL-12 (rIL-12) into mice bearing subcutaneous tumors (CSA1M fibrosarcoma) induced complete tumor regression, irrespective of whether tumors were at early or late stages of growth. Furthermore, IL-12-treated mice that had rejected the primary tumor exhibited complete resistance to rechallenge with the same tumor but did not reject a second syngeneic tumor. Immunohistochemical analyses following IL-12 treatment revealed that CD4+ and CD8+ T-cells had infiltrated the tumor. More importantly, IFN-gamma mRNA expression was observed in fresh tumor masses from tumor-bearing mice receiving IL-12 treatment. The importance of IFN-gamma was further demonstrated by the observation that systemic administration of anti-IFN-gamma monoclonal antibody prior to IL-12 treatment completely abrogated the antitumor effect of IL-12. We next investigated the ability of rIL-12 to modulate the outgrowth of metastatic tumor cells in an ovarian carcinoma (OV-HM) model. This aggressive tumor showed rapid growth of the primary tumor mass, a high incidence of metastases to the lung and lymph nodes, and invasion from the primary subcutaneous site into the peritoneal cavity. At approximately 1 month after tumor implantation, primary tumors in animals without palpable lymph nodes were surgically resected. When examined 2 months later, most animals had developed lymph node and lung metastases. In contrast, rIL-12 injections following tumor resection inhibited the development of metastases in both the lung and lymph nodes. Even in mice showing signs of lymph node metastases or invasion of the abdominal wall before primary tumor resection, rIL-12 administration following tumor resection prevented further invasion into the peritoneal cavity and metastatic tumor cell growth in the lung. Our results demonstrate that administration of rIL-12 to tumor-bearing mice results in tumor regression through mechanisms involving efficient IFN-gamma production by antitumor T-cells at tumor sites in situ and the establishment of a tumor-specific protective immune response. The results also indicate that IL-12 can induce a curative immune response in the face of an aggressive micrometastasizing tumor.

Subcutaneous recombinant interleukin-2 (rIL-2) in out-patients with metastatic renal cell carcinoma: Results of a multicenter SCAPP1 trial

This multicenter phase II trial was conducted in order to evaluate the efficacy and toxicity of the subcutaneous route of administration of rIL-2 in the treatment of patients with metastatic renal cell carcinoma and to check whether an increased cumulative dose of rIL-2 increases efficacy. Thirty-nine patients with metastatic renal cell carcinoma were included in this study. During the induction period, rIL-2 was administered subcutaneously 5 days a week for 8 weeks. The weekly dosages were 90 MIU during weeks 1 and 6;63 MIU during weeks 2 to 4 and 7 to 9. After evaluation, responders and patients with stable disease received maintenance treatment which was discontinued upon the appearance of disease progression or unacceptable toxicity. During the maintenance period, rIL-2 was administered 5 days a week for 4 weeks followed by a 2-week rest period. The weekly dosages were 90 MIU in week 1 and 63 MIU in weeks 2 to 4. After completion of induction treatment, 7 of 39 evaluable patients (18%) had objective responses (95% CI: 9% to 37%) with one complete response. Treatment was interrupted or reduced due to toxicity for seven patients: Neuropsychiatric symptoms (3 patients), joint pain (1 patient), major asthenia and anorexia (1 patient), stroke (1 patient), and septicemia (1 patient). Other systemic side effects in the remaining patients were acceptable. Seventeen patients received maintenance treatment. In none of the patients did the response status improve during this maintenance period. The median follow-up of all of the patients included was 19 months. The one- and two-year survivals were 65% and 33%, respectively, ad the median duration of response was 11 months (5 to 16+). This multicentric study confirms the efficacy of subcutaneously-administered rIL-2 in patients with metastatic renal cell carcinoma in terms of both response rate and survival. The role of a maintenance therapy needs further evaluation.

IL-12 is essential for resistance against Yersinia enterocolitica by triggering IFN-gamma production in NK cells and CD4+ T cells.

Although Yersinia enterocolitica is extracellularly located in infected tissues, a specific T cell response is required to overcome infection. Recent work implicated that in contrast to Yersinia-susceptible BALB/c mice, C57BL/6 mice are Yersinia resistant due to the rapid development of a Yersinia-specific Th1 T cell response. This study focused on the role of IL-12 in Y. enterocolitica infections in both mouse strains. We found that C57BL/6 and BALB/c mice produced comparable quantities of IL-12 mRNA after Y. enterocolitica infection. Likewise, Yersinia-infected bone marrow macrophages from both mouse strains produced equal quantities of IL-12. Administration of neutralizing anti-IL-12 Abs abrogated resistance against yersiniae in either strain. In addition, administration of rIL-12 rendered BALB/c mice resistant to yersiniae, while this treatment was toxic to C57BL/6 mice. IL-12-mediated protection was partially dependent on IFN-gamma. Spleen cells from both strains of mice produced Yersinia-triggered IFN-gamma in an IL-12-dependent manner, although those from BALB/c mice produced 10-fold lesser quantities. Administration of rIL-12 in vivo increased Yersinia-induced IFN-gamma production by BALB/c spleen cells in vitro, but decreased IFN-gamma production by spleen cells from C57BL/6 mice. IL-10 was antagonistic to IL-12 only in BALB/c mice and inhibited Yersinia-triggered IFN-gamma production. In vivo depletion experiments revealed that IL-12 accounts for Yersinia-induced IFN-gamma production by both NK cells and CD4+ T cells, the latter of which are an essential source of IFN-gamma r while NK cell-derived IFN-gamma production can be compensated by other cells. In contrast to that in the spleen, IL-12 plays a minor role in protection against yersiniae in Peyer's patches after orogastric infection. In summary, our data suggest that IL-12 is rapidly induced by Y. enterocolitica infection and required for IFN-gamma production by NK cells as well by CD4+ T cells. Although BALB/c and C57BL/6 mice produced comparable quantities of IL-12, IFN-gamma production, and thus resistance to yersiniae, can be increased by exogenous IL-12 only in BALB/c, not in C57BL/6, mice.

Immunological and side effects of low sc recombinant interleukin-2 dose in addition to conventional treatment in relapsed breast and colorectal cancer patients

Thirteen relapsed cancer patients, four of them operated for colorectal and the nine remaining for breast cancer, were cyclically given low subcutaneous (sc) recombinant interleukin-2 (rIL-2) doses in addition to chemo- or hormone therapy. Cycle intervals were 2 or 6 weeks in length, and the number of cycles ranged from one to 14 and from one to six respectively. Tolerance assessed by clinical and laboratory data, eosinophils, lymphocytes (total number), T subpopulations, B lymphocytes and NK cells were the evaluated parameters. One (7.6%) of the 13 studied patients interrupted the first low dose sc rIL-2 cycle due to a hypersensitive reaction. This case showed relapse from breast cancer. During further cycles, three patients (25%), one operated on for colorectal and two others for breast cancer of the 12 remaining cases who completed all rIL-2 cycles showed an increase in glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), gamma-gt, and creatininemia without any clinical symptoms. A slight influenza-like syndrome and 10-20 mmHg decrease in blood pressure sporadically occurred in all patients under rIL-2 therapy. In both cancer types, a significant (P < 0.05 - P < 0.001) increase in lymphocytes, eosinophils. T4 and T3 subpopulations but not in T8 subpopulations and NK cells occurred at the end of the rIL-2 cycles. In 11 of the 13 patients responsive to conventional therapy, a highly significant increase (P < 0.001) in all parameters apart from B lymphocytes and T4/T8 ratio was observed, while in three cases which were no longer responsive and in another case which had never been responsive to conventional therapy, a slightly significant increase in eosinophils only occurred (P < 0.05). Three colorectal cancer patients showed a partial response and the last a complete response to conventional therapy. In these four patients, time to progression during rIL-2 cycles ranged from 2.5-5 months and the duration of response ranged from 8-19 months. In seven of the eight breast cancer patients who completed all rIL-2 cycles, the response ranged from 3-51+ months and in the last case, which was not responsive to conventional therapy, the disease progressed in spite of the addition of rIL-2. These data suggest that: a) rIL-2 is likely to constitute a well-tolerated and suitable home therapy even when cyclically given for a prolonged period; b) following rIL-2 administration, eosinophils and lymphocytes increase in addition to the T subpopulations.

Effects of rIL-12 administration on an antigen specific immune response.

Many in vivo immune responses can be broadly categorized as either Thl or Th2-like. Murine Thl-like responses are characterized by increased IFNγ, IL-2 and IgG2a production; whereas, Th2-like responses are dominated by IL-4, IL-10, IgG, and often IgE. IL-12 has been reported to promote Thl-like responses in vitro among naive T cells (1) and to stimulate both Thl (2) and Th2 (3) clones to produce IFNγ, although the latter was determined to be transient. In addition, IL-12 was proposed as a powerful adjuvant, useful in driving protective Thl-like responses during primary Leishmania major infection (4).

Two cases of tongue cancer treated with intra‐ and peri‐tumoral injection of recombinant interleukin‐2 alone: immunohistochemical considerations to clinical tumor response

Two cases with stage II tongue cancer who exhibited different responses to intra- and peri-tumoral administration of rIL-2 alone are presented. Special consideration is given to the relationship between tumor responses to rIL-2 and clinicopathological and immunohistopathological findings. The patient who responded completely to treatment showed an exophytic tumor growth pattern, low-grade cancer invasion, and predominant infiltration of CD8+ lymphocytes over CD4+ lymphocytes in cancer cell nests. The non-responder showed endophytic tumor growth, high-grade cancer invasion, and uniform distribution of both CD4+ and CD8+ lymphocytes in cancer cell nests. Distribution of adequate amounts of T lymphocytes subsets may be necessary in order for good tumor response to biotherapy with rIL-2; other clinical and histopathological variables predicting the effect for cancer chemotherapy remain to be identified.

Reduction of Therapeutic Efficacy by a Second Cycle of PEG-IL-2

Summary: The formation of antibodies with interleukin-2 (IL-2)-neutralizing capacity and their possible impact on successful locoregional PEG-IL-2 therapy was studied in the guinea pig Line 10 (L10) tumor model. Previously it was shown in this animal model that intratumoral therapy with polyethylene glycolmodified human recombinant IL-2 (PEG-IL-2) induced tumor regression and eradication of lymph node metastases. Therefore, the putative negative effects of IL-2-neutralizing antibodies can be studied in this model. In two similar experiments, animals were immunized by subcutaneous injections (3x/week for 5 weeks) with PBS/BSA, rIL-2, or PEG-IL-2. One week after the last injection, L10 tumor cells were inoculated contralaterally on the flank. Seven days after tumor transplantation, intratumoral treatment with PBS/BSA or PEG-IL-2 was started. During immunization and subsequent intratumoral therapy, sera were collected from the guinea pigs and tested in the CTLL-16 bioassay for IL-2-inhibitory activity. Intratumoral injections with PBS/BSA after immunization only incidently resulted in cure of tumor and metastases, suggesting that by sensitization treatment alone, the immune system was not sufficiently activated to eradicate a tumor inoculum. PBS/BSA immunization followed by intratumoral PEG-IL-2 therapy resulted in complete cure of primary tumor and lymph node metastases in all treated animals. Immunization with rIL-2 evoked IL-2-inhibitory activity in the serum of all guinea pigs. Nonetheless, six of these 11 rIL-2-immunized animals were completely cured by intratumoral PEG-IL-2 therapy. PEG-IL-2 immunization resulted in IL-2- inhibitory serum activity in three of 12 guinea pigs. The guinea pigs with high IL-2-neutralizing activity in their serum showed progressive growth of tumor and metastases, whereas the other animals were completely cured. The level of IL-2-neutralizing capacity in the sera from rIL-2-pretreated animals was higher than that from PEG-IL-2-pre treated guinea pigs, confirming a reduced immunogenicity of PEG-IL-2 as reported after intravenous administration. Passage of the sera from the immunized guinea pigs over a protein G column drastically reduced IL-2-inhibitory activity, implying IgG-related IL-2 inactivation. In conclusion, IL-2-neutralizing activity, possibly mediated by IgG antibodies, is more readily induced by intradermal rIL-2 administration than by PEG-IL-2 injections. Our data suggest that local treatment of cancer patients with a second cycle of PEG-IL-2 after previous therapy with rIL-2 or PEGIL- 2 may reduce the therapeutic efficacy of PEG-IL-2.

Lack of efficacy of low‐dose subcutaneous recombinant interleukin‐2 and interferon‐a in the treatment of metastatic renal cell carcinoma

To evaluate the efficacy and toxicity of subcutaneous immunotherapy using a combination of recombinant interleukin-2 (r-IL2) and interferon-alpha (IFN-alpha) for the treatment of patients with metastatic renal cell carcinoma (RCC). Initially a maximum of 45 patients with advanced RCC were to be included in the study, according to a Fleming three-stage procedure. To be included patients had to have measurable metastasis. Of a potential 45 patients with advanced RCC, 15 patients were included in the study (10 men and five women, mean age 51 years, range 25-69). From the first week of treatment r-IL2 was given subcutaneously on day 1 to 5, at 18 x 10(6) units once a day and then 9 x 10(6) units once a day for the following 5 weeks. IFN-alpha was given three times a week for the last 5 weeks. Minimum follow-up was 6 months. All patients initially underwent radical nephrectomy. Seven patients were found to have metastases at the time of diagnosis. All patients received ambulatory therapy, except for the first 5 days of treatment. Overall, 80% of the patients received more than 75% of the complete dose of r-IL2. One patient suffered toxicity greater than the World Health Organization (WHO) grade 2 (neutropenia). No patient had a complete or partial response, two patients had a minor response, two patients had stable disease and 11 patients had disease progression. Subcutaneous r-IL2 and IFN-alpha had no beneficial effect on the first 15 patients and the study was discontinued, in accordance with the Fleming rules. The dose, administration and combination of r-IL2 and IFN-alpha may explain the lack of efficacy. Other studies have shown that low doses of r-IL2 are not effective and the superiority of the combination of r-IL2 and IFN-alpha has not been proven. Therefore, a high dose of r-IL2, in association with other cytokines, chemotherapy and adoptive immunotherapy, may be the only way to improve the response rate of metastatic RCC.

CD28-B7 blockade after alloantigenic challenge in vivo inhibits Th1 cytokines but spares Th2.

Blocking the CD28-B7 T cell costimulatory pathway with the fusion protein CTLA4Ig inhibits alloimmune responses in vitro and in vivo and induces tolerance to cardiac allografts in mice and rats, but the mechanisms mediating the tolerant state in vivo are unknown. Here, we report the effects and potential mechanisms of CTLA4Ig in the rat renal allograft model. LEW rats were nephrectomized and received renal allografts from major histocompatibility complex-incompatible WF rats. While all untreated and control immunoglobulin (Ig)-treated animals acutely rejected their allografts and died, 86% of rats that received a single injection of CTLA4Ig on day 2 after transplantation had prolonged survival (> 60-100 days) with preserved renal function. By contrast, only 29% of animals that received CTLA4Ig on the day of engraftment had prolonged survival. Long-term survivors (> 100 days) exhibited donor-specific tolerance, accepting donor-matched WF but acutely rejecting third-party BN cardiac allografts. Immunohistological analysis of grafts sampled at 1 week after transplantation showed that both control and CTLA4Ig-treated animals had mononuclear cell infiltrates, with a higher percentage of CD4+ cells in the CTLA4Ig-treated group. However, while this was associated with vasculitis and tubulitis in control grafts, there was no evidence of tissue injury in CTLA4Ig-treated animals. The immune response leading to graft rejection in control animals was characterized by expression of the T helper (Th) type 1 cytokines interleukin (IL)-2 and interferon-gamma. In contrast, the persistent CD4+ infiltrate without graft rejection in CTLA4Ig-treated animals was associated with increased staining for the Th2-related cytokines IL-4 and IL-10. Furthermore, grafts from CTLA4Ig-treated animals had marked upregulation of intragraft staining for IgG1, but not IgG2a or IgG2b. Administration of rIL-2 to CTLA4Ig-treated animals restored allograft rejection in 50% of animals tested. These results confirm that blockade of the CD28-B7 pathway after alloantigenic challenge induces donor-specific acceptance of vascularized organ allografts, and indicates in this model that CTLA4Ig inhibits Th1 but spares Th2 cytokines in vivo.

Human Recombinant IL-2 Augments Immunoglobulin and Induces Rheumatoid Factor Production by Rheumatoid Arthritis Lymphocytes Engrafted into Severe Combined Immunodeficient Mice

Recombinant (r) human IL-2 was administered in vivo to improve homing and engraftment of rheumatoid arthritis (RA) patients' peripheral blood mononuclear cells (PBMC) into severe combined immunodeficient (SCID) mice. Human rIL-2 treatment resulted in augmented human Ig production and induced IgM rheumatoid factor (RF) of human origin in SCID-RA chimeras. The increment of human serum IgG in SCID-RA chimeras after IL-2 treatment ranged between 15 and 43% and for IgM between 50 and 98% during 2-8 weeks postengraftment. Human IgM-RF was detectable after 1 to 2 weeks after engraftment and persisted over a period of 10-13 weeks. No RF was produced in SCID mice engrafted with PBMC from healthy individuals with or without exogenous rIL-2 administration. Thus, human rIL-2 expanded autoreactive clones involved in the production of RF in the SCIDRA chimeras. The present study provides a novel approach to establish an in vivo SCID-RA model to study the cellular and molecular mechanisms involved in the production of RF and development of a RA-like lesion.

Sustained-release interleukin-2 following intramuscular injection in rats

A potential sustained-release recombinant interleukin-2 (rIL-2) formulation was evaluated following intramuscular (i.m.) injection in rats. Poloxamer 407 (Pluronic® F-127) is a block copolymer comprised of polyoxyethylene and polyoxypropylene segments which exhibits the property of reverse thermal gelation. Thus, an rIL-2/poloxamer 407 preparation was injected i.m. in rats as a viscous mobile solution with subsequent gelation in vivo. Resultant plasma rIL-2 concentration-time data indicated absorption rate-limited disposition of rIL-2 following i.m. injection. The mean values of the absorption rate constant ( k clim were 0.64 ± 0.073 and 0.21 ± 0.019 h −1 following i.m. injection of an rIL-2 aqueous solution and the HL-2 gel formulation, respectively. The mean values of the elimination rate constant (k elim) were 1.76 ± 0.22 and 1.21 ±0.079 h −1 following administration of rIL-2 as an aqueous solution or gel formulation, respectively. The blood sampling time point at which the greatest plasma rIL-2 concentration (C max .) was observed was 2 h for rats injected i.m. with rIL-2 formulated in poloxamer 407 compared to 1 h for rats injected i.m. with an rIL-2 aqueous solution. The mean value of the C max. was significantly ( p < 0.05) less in rats injected i.m. with the rIL-2 gel formulation ( C max= 12500 ± 1450 pg/ml) compared to rats injected i.m. with an aqueous solution of rIL-2 ( C max = 19 600 ± 2650 pg/ml). The bioavailability of rIL-2 when injected i.m. as an rIL-2/poloxamer gel formulation relative to an i.m. injection of an rIL-2 aqueous solution was approx. 1.0. Cumulative amounts of rIL-2 recovered in the urine 48 h after an i.m. injection of either an rIL-2 aqueous solution or rIL-2 gel formulation were less than 1 percent of the administered dose. Since the rIL-2/poloxamer formulation evaluated in this study resulted in a decrease in the maximum blood concentration of rIL-2 achieved and an increase in the time required to reach a maximum blood concentration, without a reduction in the bioavailability of the protein, the rIL-2 gel formulation may represent an alternative, sustained-release mode of rIL-2 administration.

Systemic administration of rIL-12 induces complete tumor regression and protective immunity: response is correlated with a striking reversal of suppressed IFN-gamma production by anti-tumor T cells.

Unfractionated spleen cells taken from tumor-bearing mice 2 weeks after tumor implantation contained tumor-primed T cells which produced cytokines including IL-2 and IFN-gamma when cultured in vitro. With progressive tumor growth this initial lymphokine-producing capacity decreased. Here, we investigated the ability of IL-12 to (i) restore suppressed IFN-gamma production, (ii) cause tumor regression and (ii) induce anti-tumor protective immunity. Addition of rIL-12 to spleen cell cultures from 4- to 10-week-old tumor-bearing mice resulted in a striking enhancement in the production of IFN-gamma compared with cultures of these cells in the absence of rIL-12 or of normal spleen cells in the presence of rIL-12. Five i.p. injections of rIL-12 into mice bearing s.c. tumors induced complete tumor regression. This was found when rIL-12 was given at early (1-2 weeks), intermediate (4-5 weeks) or even late (7 weeks) stages of tumor growth. Furthermore, IL-12-treated mice which rejected the primary tumor exhibited complete resistance to a rechallenge with the same tumor but did not reject a second syngenetic tumor. Immunohistochemical analyses following IL-12 treatment revealed that CD4+ and CD8+ T cells infiltrate the tumor. More importantly, IFN-gamma mRNA expression was observed in fresh tumor masses from tumor-bearing mice receiving IL-12 treatment. The importance of IFN-gamma was further demonstrated by the observation that the systemic administration of anti-IFN-gamma mAb prior to IL-12 treatment completely abrogated the anti-tumor effect of IL-12. Thus, these results indicate that administration of modest levels of rIL-12 to tumor-bearing mice results in tumor regression through mechanisms involving reversal of suppressed IFN-gamma production by anti-tumor T cells and the establishment of a tumor-specific protective immune response.

Adoptive CD8+ T-cell immunotherapy of AIDS patients with Kaposi's sarcoma.

This article reviews published and original findings from two clinical trials of adoptive CD8+ T-cell immunotherapy of patients with acquired immunodeficiency syndrome (AIDS) and Kaposi's sarcoma (KS). In the first trial, AIDS patients with either KS or oral hairy leukoplakia (OHL) received five rounds of reinfusions of 10(8)-10(10) ex vivo expanded and activated autologous CD8+ T cells. Recombinant interleukin-2 (rIL-2) was coadministered only with the fifth and final infusion. Improvement, and in some cases, resolution of OHL, KS, and candidiasis was observed with no side effects. The observation that clinical improvement of KS was more pronounced when reinfusion of CD8+ T cells was followed by rIL-2 infusion led to a second clinical trial designed to examine the effect of repeated infusions of autologous CD8+ T cells with concomitant rIL-2 administration in the treatment of AIDS-related KS. Improvement of KS status was observed in four out of the eight patients studied (three partial and one complete response). The CD8+ T-cell immunotherapy protocol also provided the opportunity to comparatively study CD8+ T-cell-associated genetic programs. Baseline expression patterns of soluble and surface immune markers by CD8+ T cells from AIDS patients and uninfected controls were predominantly of the type 1 type and differed mainly at a quantitative or kinetic level. Deficiencies in immune mediator expression by CD8+ T cells from AIDS patients tended to dissipate with progression through the protocol. Findings are discussed in the context of current knowledge and therapeutic implications of CD8+ T-cell function in AIDS and neoplasia.

Suppressed thyroid-stimulating hormone secretion in patients treated with interleukin-2 and interferon-?2b for metastatic melanoma

Recent reports suggest that combined therapy with recombinant interleukin (IL)-2 and interferon (IFN) alpha 2b may result in autoimmune-induced thyroid dysfunction. We prospectively analyzed thyroid function for 6 weeks in two groups of patients with progressive metastatic melanoma treated according to two different protocols. In group I (n = 17) three treatment cycles were given, each with three weeks of subcutanous administration of rIL-2 and INF-alpha 2b at different doses. In group II (n = 13) the chemotherapeutic agent dacarbazine was given in addition. In group 1 three patients developed frank hyperthyroidism, which required antithyroid drug therapy in one case. Autoantibodies against thyroid microsomal antigen, thyroglobulin, and the thyroid-stimulating hormone (TSH) receptor were not significantly elevated in any of these patients. However, the remaining 14 patients showed a significant decrease in TSH after 6 weeks of treatment, from 1.8 +/- 0.9 to 0.7 +/- 0.7 microU/ml (P < 0.02). Thyroid hormones (triiodothyronine, thyroxine, free thyroxine) also increased during the observation time, but this did not parallel the drop in TSH levels. Only thyroxine increased above the upper limit of normal, while triiodothyronine and free thyroxine stayed within the normal range. In group II, 6 of 13 patients (46%) had a decreased TSH after 6 weeks of treatment. Mean TSH was 1.5 +/- 1.4 before and 0.8 +/- 0.6 microU/ml after 6 weeks and was totally suppressed in three cases. None of these patients showed ouvert hyperthyroidism. Hypothyroidism was not observed in either group.(ABSTRACT TRUNCATED AT 250 WORDS)