Response Of Lymph Node Cells Research Articles

Polyclonal cell activity of a repeat peptide derived from the sequence of an 85-kilodalton surface protein of Trypanosoma cruzi trypomastigotes

Some in vitro and in vivo biological activities of an octadecapeptide derived from an 85-kDa surface protein of Trypanosoma cruzi trypomastigote were studied. The peptide coupled to a carrier protein induced the proliferative response of lymph node cells from mice immunized with various antigens. Moreover, sera from mice immunized with the coupled peptide were found to contain antibodies against a number of self and nonself antigens: fibronectin, bovine serum albumin, myosin, tetanus toxoid, ovalbumin, keyhole limpet hemocyanin, and DNA. These results are discussed in the context of Chagas' disease immunopathology.

ICAM-1-dependent pathway is critically involved in the pathogenesis of adjuvant arthritis in rats.

Intercellular adhesion molecule 1 (ICAM-1) plays important roles in immune responses. In order to examine whether ICAM-1 is involved in pathogenesis of adjuvant arthritis (AA), we investigated the effect of anti-ICAM-1 mAb, 1A29, on AA in rats. In vivo administration of 1A29 exerted a very strong suppressive effect on the development of arthritis and induced a marked reduction of inflammatory parameters. 1A29 suppressed the Ag-specific proliferative response of lymph node cells from AA rats, suggesting that the mAb blocked the Ag recognition phase. The study using adoptive transfer of AA revealed that 1A29 completely inhibited production of arthritogenic lymphocytes in donors and partially suppressed progression of arthritis in recipients caused by these lymphocytes. These findings indicated that the inhibitory effect of 1A29 on development of arthritis was at least twofold, i.e., 1) interference with cell-cell interaction between APC and T cells, which resulted in abrogation of effector cell generation; and 2) blocking of effector cell migration to inflammatory lesions. These results indicated that ICAM-1-dependent pathway is critically involved in the pathogenesis of AA. The data support the concept that ICAM-1-dependent pathways are important in chronic inflammatory disease.

Specific proliferative responses following the induction of experimental SLE in mice

We have previously reported the induction of experimental systematic lupus erythematosus (SLE) in mice by immunization with a human monoclonal antibody that expresses a common anti-DNA idiotype (16/6 Id). Following immunization, antibodies directed against various nuclear autoantigens could be detected in the sera of the mice. In the present study, we investigated the proliferative responses of lymph node cells to one particular autoantigen (DNA) following the induction of experimental SLE. Cells reactive with ssDNA could be detected following immunization of BALB/c mice with the 16/6 Id. The appearance of these DNA-reactive cells succeeded the appearance of 16/6 Id-specific cells. The activation of this subset of autoreactive cells could be achieved only by the immunization of the mice with the 16/6 Id, but not by their immunization with DNA, thus suggesting that the induction of experimental SLE is associated with the alteration of the low responsive potential of the mice to DNA.

Lymphocytes from SJL/J mice immunized with spinal cord respond selectively to a peptide of proteolipid protein and transfer relapsing demyelinating experimental autoimmune encephalomyelitis.

Relapsing experimental autoimmune encephalomyelitis (R-EAE) can be induced in SJL/J mice by immunization with spinal cord homogenate and adjuvant. The specific Ag(s) responsible for acute disease and subsequent relapses in this model is unknown. Myelin basic protein (BP), an encephalitogenic peptide of BP (BP 87-99), and proteolipid protein (PLP) can each induce R-EAE in SJL/J mice, and a peptide of PLP (PLP 139-151) has been reported to induce acute EAE. To determine the encephalitogens in cord-immunized mice with R-EAE, the in vitro proliferative responses of lymph node cells (LNC) and central nervous system mononuclear cells to BP, BP peptides, and PLP peptides were examined during acute EAE and during relapses. LNC responded only to PLP peptides 139-151 and 141-151 and did not respond to BP or its peptides during acute or chronic disease. Central nervous system mononuclear cells also preferentially responded to PLP 139-151 and 141-151 during acute and relapsing disease. A PLP 139-151 peptide-specific Th cell line was selected from LNC of cord-immunized donors. Five million peptide-specific line cells transferred severe relapsing demyelinating EAE to naive recipients. We conclude that PLP peptide 139-151 is the major encephalitogen for R-EAE in cord-immunized SJL/J mice. We demonstrate for the first time that Th cells specific for this peptide are sufficient to transfer relapsing demyelinating EAE. The predominance of a PLP immune response rather than a BP response in SJL/J mice suggests that genetic background may determine the predominant myelin Ag response in human demyelinating diseases such as multiple sclerosis.

Protective efficacy of a cloned Brugia malayi antigen in a mouse model of microfilaremia.

Immunization of mice with irradiated Brugia larvae or parasite extracts has been shown to induce partial resistance to microfilaremia and enhance clearance of infective larvae. We recently reported the cloning of a 548 amino acid 62-kDa Brugia malayi Ag identified on the basis of reactivity with antisera to a subset of protective microfilarial Ag. Our study describes the protective efficacy against microfilaremia in mice, immunogenicity, and parasite stage-specificity of this candidate vaccine molecule. Immunization of Swiss or BALB/c mice with 1 to 3 micrograms of a 92-kDa trpE fusion protein encoding amino acids 1-479 reduced the intensity of microfilaremia by 40 to 60% compared to control animals given buffer or bacterial trpE (p less than 0.01 to 0.001). Mice immunized with the 92-kDa fusion protein developed delayed-type hypersensitivity reactivity to B. malayi as assessed by enhanced footpad swelling 24 and 48 h after intradermal injection of adult worm extract and in vitro lymph node mononuclear cell proliferation (3H-thymidine uptake) in response to the fusion protein (mean +/- SD stimulation index 4.7 +/- 0.8 vs 2.0 +/- 1.4 for trpE, p less than 0.05). Proliferative responses of lymph node cells coincubated with three other fusion proteins corresponding to the filarial protein truncated from its carboxyl-terminus suggest that dominant T cell epitopes of the 62-kDa Ag are encompassed by amino acids 437-479. Rabbit antibody to the 92-kDa trpE fusion protein immunoprecipitated a 62-kDa polypeptide from [35S] methionine biosynthetically labeled B. malayi microfilariae, adult female, and adult male worms. These data indicate that a recombinant Ag expressed in several developmental stages of B. malayi is capable of inducing partial resistance against microfilariae and Ag-specific T cell responses in mice.

Analysis of type II collagen‐reactive T cells in the mouse I. Different regulation of autoreactive vs. non‐autoreactive anti‐type II collagen T cells in the DBA/1 mouse

The T cell reactivity against type II collagen (CII) was analyzed in the collagen-induced arthritis-susceptible mouse strain DBA/1. It was shown that the proliferative response in lymph node cells from rat CII-immunized mice was mainly directed against a foreign determinant present on all heterologous CII tested but not on autologous CII. A T cell line with this reactivity reacted with high sensitivity with CII and the determinant was mapped to the CB11 fragment of CII. A weak autoreactive response could be detected in the primary cultures using high concentrations of mouse CII and this reactivity remained after several stimulations with high concentrations of rat CII but not with low concentrations of rat CII. A similar response against mouse CII but with only limited cross-reactivity to rat CII was seen when culturing the cells with mouse CII as antigen. The optimal concentration for the autoreactive response was always more than 100-fold higher than for the response of the T cells specific for heterologous CII. An anti-CII T cell response could also be detected in spleen cells from unimmunized mice and the strongest response was obtained using autologous CII. These results suggest that T cells recognizing self CII are normally activated in the DBA/1 mouse and possibly as a consequence exhibit a clonal anergy pattern with a weak proliferative response only at high concentrations of CII.

Trypanosoma cruzi: Maintenance of parasite-specific T cell responses in lymph nodes during the acute phase of the infection

Mice infected with 5 × 10 3 forms of Trypanosoma cruzi showed a transient, but severe impairment of in vitro spleen cell responses to parasite antigens and to Concanavalin A (Con A). In contrast, inguinal and periaortic lymph node (LN) cells displayed high parasite-specific proliferative responses and only a partial reduction of the Con A-induced proliferation during the acute and chronic phases of infection. Lymphocytes that underwent blastic transformation in T. cruzi-stimulated cell cultures were of the L3T4 + phenotype. Suppression of spleen cell responses occurred in the acute phase whether mice were infected with high (3 × 10 5) or low (5 × 10 3) doses of T. cruzi by intraperitoneal or subcutaneous route. Suppression of the T. cruzi-specific proliferative response of LN cells was only observed in mice infected with high subcutaneous inocula. This suppression, however, was restricted to the LNs draining the site of inoculation without affecting distant LNs. Supernatants from parasite-stimulated proliferating LN cells displayed low or undetectable T cell growth factor (TCGF) activity, in contrast with the high TCGF levels found in supernatants of the same cells stimulated with Con A. Low levels of TCGF were also detected in cultures of LN cells from mice immunized with T. cruzi extracts. Neither the T. cruzi antigen used for in vitro stimulation nor the LN cell supernatants from infected mice inhibited TCGF activity. These findings indicate that (1) parasite-specific responses are present in the LN compartment throughout the acute phase of T. cruzi infection in mice and (2) the proliferative response of L3T4 + LN cells from infected mice to T. cruzi antigens is not associated with a high TCGF secretory response.

The relative roles of major and minor histocompatibility antigens in the induction of immunologic unresponsiveness by blood transfusion.

Renal allograft survival may be prolonged indefinitely in some strains of rats following preoperative transfusion with whole blood from the organ donor. Similarly donor-specific transfusion results in a reduction in the proliferative response of lymph node (LN) white cells (WBCs) to donor-specific stimulators in mixed-lymphocyte culture (MLC). To determine the relative roles of major and minor histocompatibility antigens in the depression of the proliferative response, in vitro lymphocyte proliferation assays were performed using congenic rat strains as blood donors. Unidirectional MLCs were set up between haplotype-disparate responder and stimulator LN cells, in cases in which the responding cells had been harvested from rats transfused with blood that shared either some, all, or none of the major histocompatibility complex genes with the stimulator strain. The proliferative response of LN cells harvested from rats transfused with blood sharing major (class I or II) or minor antigens, or both, with the in vitro stimulator cells was significantly less than the response of cells harvested from nontransfused controls. No single-locus product was more or less effective than whole blood in depressing cell proliferation. These data suggest that the beneficial effect of preoperative random blood transfusions observed in clinical transplantation may arise from the fortuitous sharing by the blood donor and the subsequent organ donor of not only a single major histocompatibility antigen but also of minor histocompatibility antigens.

Anti-CD4 monoclonal antibody effects cellular hyporesponsiveness and prolongs renal allograft survival in the rat

LEW strain rats received BN strain renal allografts and were treated with daily injections of 100 μg BWH-4, a new IgG2a mouse anti-rat CD4 monoclonal antibody, intravenously for 5 to 10 days. These animals had a median actuarial survival of 28 days. Control animals rejected their grafts and died of uremia between day 6 and 8 post transplant. Animals treated with BWH-4 did not suffer acute graft loss and had stable renal function throughout the follow-up period of 5 weeks. Peripheral blood, lymph node, and splenic lymphocytes showed 60–80% decrease in the CD4+ subset which normalized by 4 weeks after transplantation. There was depressed proliferative response of lymph node cells to alloantigen and mitogen which persisted up to 4 weeks after cessation of therapy. Treated animals produced anti-BN antibodies as well as antibodies to the infused BWH-4. There was no correlation, however, between these humoral responses and allograft function. We conclude that low-dose monotherapy with the BWH-4 anti-CD4 monoclonal antibody effects cellular hyporesponsiveness, prevents acute renal allograft rejection, and prolongs survival.

Immunodominant sites of human T cell lymphotropic virus type 1 envelope protein for murine helper T cells.

HTLV-I (human T cell lymphotropic virus type 1) is the retrovirus causally related to adult T cell leukemia/lymphoma and is also associated with a neurological disorder, tropical spastic paraparesis, or HTLV-I-associated myelopathy. The development of these two different diseases among HTLV-I-infected individuals may depend in part on differences in their T cell immunity associated with a difference of HLA phenotype. Peptides corresponding to 17 sites in the HTLV-I envelope protein were tested for their antigenicity for lymph node cells from B10.BR, B10.D2, B10.A(5R), and B10.HTT congenic mice, representing four independent MHC haplotypes, immunized with the native envelope protein. Ten of the 17 tested sites were predicted to be amphipathic alpha-helical sites and all of them were found to be antigenic for at least one of the four MHC congenic strains of mice. Three of the 17 sites were amphipathic 3(10)-helical sites and four sites were predicted to be non-helical sites: none of the 3(10)-helical sites were antigenic and only one of four non-predicted sites was found to be immunodominant. Furthermore, three potent immunodominant peptides, V1E1 (342-363), V1E8/SP4a (191-209), and V1E10 (141-156) were also shown to be immunogenic; i.e., these peptides could be used to immunize mice to elicit proliferative responses of lymph node cells to the native HTLV-I envelope protein. Furthermore, these three peptides were able to prime animals for an enhanced antibody response to the native protein. Because this priming followed the same Ir gene control as the proliferative response, it probably reflects the ability of these peptides to prime helper T cells. The localization of immunodominant sites in HTLV-I envelope protein in mice may be useful for finding antigenic and immunogenic sites in humans, for developing a peptide vaccine for the virus, and possibly for aiding in prognosis for the development of different disease manifestations of HTLV-I infection.

Different T helper cell subsets elicited in mice utilizing two different adjuvant vehicles: The role of endogenous interleukin 1 in proliferative responses

Mice were immunized with either poly(Glu, Arg, Ala) or poly(Glu, Lys, Phe) contained in two different adjuvant preparations, alum (AlK(SO 4) 2) or complete Freund's adjuvant (CFA), and in vitro antigen-driven proliferative responses of lymph node cells were assayed 4–16 days later. After immunization with antigens on alum, endogenous interleukin 1 (IL-1) as well as interleukin 4 (IL-4) production was required for the proliferation of the elicited T cells as inclusion of either polyclonal goat anti-mouse IL-1 α or monoclonal anti-mouse IL-4 (11B11) in the cultures inhibited proliferative responses to antigen. In contrast, proliferative responses of cells elicited by antigen in CFA were not inhibited by either anti-IL-1 or anti-IL-4. Monoclonal anti-mouse CD4 (GK1.5) inhibited proliferative responses regardless of which adjuvant was used to elicit antigen-reactive cells. These data indicated that phenotypically different subpopulations of CD4 + cells were elicited by the same antigen administered in different adjuvant preparations, Th2-like cells after immunization with polymers on alum and Th1-like cells after immunization with antigens in CFA. An examination of the isotypes of polymer-specific antibodies present in the sera of immunized mice also supported this conclusion.

Differential effect of cyclosporine in vivo on the distribution of T cell subsets in the thymus, spleen, and lymph nodes.

Cyclosporine treatment of BALB/c mice (at a dose of 20 mg/kg every other day for 3 weeks) caused a remarkable reduction in the PNA-, L3T4+Lyt-2- subset of thymocytes. A significant reduction of the L3T4+Lyt-2-subset was also observed in both the lymph node and spleen cells of CsA-treated mice, though the degree of the reduction was lower than that in thymocytes. Both lymph node and spleen cells from CsA-treated mice showed a significant increase in the percentage of Thy-1.2 negative, L3T4-Lyt-2- cells (perhaps B cells). Thymocytes from CsA-treated mice showed a reduction in the in vitro proliferative responses to Con A and PHA. On the other hand, there was a slight, but not significant, decrease in the responses of lymph node cells to Con A, PHA and LPS. Spleen cells from CsA-treated mice showed a significant reduction in the responses to Con A and PHA, though the degree of the reduction was lower than that of thymocytes. There was a significant decrease in the proliferative response of spleen cells to LPS. These results suggest that CsA affects both thymus and spleen cells in vivo, preferentially impairing the L3T4+Lyt-2- subset (helper T cells or their precursors) within the thymus. The lymph node cells seem to be relatively spared from the in vivo effect of CsA compared with cells in the thymus and spleen.

Abrogation of Spleen Macrophage Suppressive Activity by 15-Deoxyspergualin

We studied the immunomodulatory mechanism of 15-deoxyspergualin (DSG), a novel antitumor agent. To assess this, we used a mixed culture of antigen-primed lymph node cells (LNC) and spleen cells (SPC). In normal or untreated conditions, SPC suppressed the proliferative response of LNC to the antigens. In contrast, SPC from DSG-treated animals did not show any suppressive activity. This suppression was mediated by adherent cells in SPC but the suppression mechanism was recovered when DSG-treated spleen macrophages were reconstituted with control spleen nonadherent cells. These data suggest that DSG abrogates nonspecific suppressive activity of spleen cells by acting on both adherent and nonadherent cells.

Modulation of natural killer activity by 12-O-tetradecanoylphorbol-13-acetate and benzoyl peroxide in phorbol ester-sensitive (SENCAR) and resistant (B6C3F1) mice.

Following two weeks of topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA) at 2, 4 and 8 micrograms/mouse on alternate days (7X total) or benzoyl peroxide (BZP) at 10, 20 and 40 mg/mouse, natural killer (NK) activity was determined in local (lymph nodes draining the lower dorsal region) and systemic (spleen) lymphoid tissue in phorbol ester-sensitive (SENCAR) and resistant (B6C3F1) mice. SENCAR mice, sensitive to tumor induction by TPA in two-stage chemical-induced carcinogenesis protocols, demonstrated suppression of NK activity in the spleen (no significant change in lymph nodes) and substantial dose-dependent increases in cell numbers in these organs after topical exposure to TPA. B6C3F1 (C57BL/6 X C3H F1) mice, reported to be resistant to TPA-induced promotion, demonstrated significant increases in NK activity in lymph nodes/spleen with an increase in cell numbers in the draining nodes only. Unlike the C57BL/6 parental strain, B6C3F1 mice are also reported to be resistant to promotion with BZP. Significantly, studies in this laboratory indicated that B6C3F1 mice dosed with BZP demonstrated increased NK activity in the spleen as was observed after dosing with TPA. These data suggest that alterations in NK activity as a result of exposure to tumor promoters may, in part, account for the resistance of particular strains of mice to tumor development. In both SENCAR and B6C3F1 mice, the blastogenic response of spleen cell suspensions isolated from TPA-dosed animals to phytohemagglutinin (PHA), a T cell lectin, was suppressed in a dose-dependent manner; BZP had no effect on spleen cell responses in either strain. Blastogenic responses of lymph node cells to PHA were enhanced in both strains of mice after topical application of TPA and BZP. Therefore, alterations in lymphoid cell responsiveness to PHA appeared unrelated to the reported sensitivities of SENCAR and B6C3F1 mice to tumor promotion.

Genetic control of the immune responsiveness to Streptococcus mutans by the major histocompatibility complex of the rat (RT1).

The lymph node cells from 11 strains of rats, differing in the genotype of the major histocompatibility complex of the rat (RT1), were examined on the basis of their proliferative response to the cell wall antigen of Streptococcus mutans. The 11 rat strains fell into three groups: high, intermediate, and low responders. To demonstrate the influence of the major histocompatibility complex on immune responsiveness to S. mutans, further experiments were performed using the RT1-congenic rat strains WKAH.1L(LEW), WKAH. 1AV1(ACI), and WKAH.1J(LEJ), which differ only in the genotype of the RT1 region. Although the background genes of each strain were of WKAH origin, WKAH.1L(LEW) and WKAH.1AV1(ACI) rats showed a low response whereas WKAH.1J(LEJ) rats showed a moderate response to the S. mutans cell wall antigen. The results indicate that the immune response is controlled by the class II gene(s) in RT1. Furthermore, the RT1.D locus products were shown to play an important role in the restriction molecule, since a monoclonal antibody, HOK7, directed to the RT1.Dk locus products reduced the proliferative response of lymph node cells.

Cross-reactivity between haptenic muramyl di- or tripeptide derivatives and Mycobacterium bovis BCG: potential application for enhancing tumor immunity.

Muramyl di- or tripeptide (MDP or MTP) hapten derivatives bearing various structures were synthesized, and the correlation of these structures with cross-reactivity with Mycobacterium bovis BCG and their applicability to enhance induction of syngeneic tumor immunity were investigated. The cross-reactivity of MDP or MTP haptens to BCG was examined by T-cell proliferation responses of lymph node cells from BCG-primed C3H/He mice in the stimulation with MDP- or MTP-coupled syngeneic cells. A haptenic MDP derivative (designated L4-MDP) stimulated proliferative responses appreciably. Derivatives in which alanine in the peptide portion of L4-MDP was replaced by methylalanine or valine failed to induce stimulation. However, the cross-reactivity with BCG was regained in the MTP derivative that was formed by adding lysine to dipeptide containing methylalanine or valine. Whether this cross-reactive pattern was correlated with enhanced induction of tumor immunity was further investigated. According to the established protocol for the augmented induction of tumor immunity, BCG-primed C3H/He mice were immunized with various haptenic MDP-coupled syngeneic X5563 tumor cells. Immunization with tumor cells conjugating BCG-cross-reactive haptens resulted in enhanced tumor immunity, whereas immunization with tumor cells coupling non-cross-reactive haptens failed to produce anti-X5563 tumor immunity. These results indicate that the peptide portion in these haptenic structures is critical in the generation of BCG cross-reactivity leading to enhanced tumor immunity.

ABA-specific responses are I region restricted by the carriers used for immunization.

Immunization of mice with ABA coupled to carriers to which they are nonresponders gives rise to ABA-specific proliferative responses in lymph node cells. When C3H/HeN and CBA/J nonresponder mice are immunized with ABA on (T,G)-A-L (an I-A-restricted carrier in responder mice), the responses to ABA-tyr and ABA coupled to a variety of unrelated carriers are solely I-A restricted as determined by inhibition with anti-IA and anti-I-E sera. When ABA on GLT (an I-E-restricted carrier in responder mice) is used for immunization, the responses are both I-A and I-E restricted. Thus, ABA-specific responses in nonresponder mice appear in part to be restricted by the carrier used for immunization. B10.S mice, lacking functional I-E molecules, channel their ABA-specific responses entirely through I-A when immunized with ABA-GLT. These results support the hypothesis that the failure in nonresponders lies in a functional deficit in the T cell repertoire rather than an inability of accessory cells to present antigen.

Characterization of cellular immune response to chemically defined glycoconjugates from Leishmania mexicana subsp. amazonensis

Two defined glycoconjugates (GP-10/20 and FR II Phe) purified from Leishmania mexicana subsp. amazonensis were analyzed with respect to their ability to induce cellular responses in immunized and infected mice. Each glycoconjugate was recognized by specific immune cells, as assessed by the proliferative response of lymph node cells of immunized mice. The response to GP-10/20 depended on helper T cells and antigen-presenting cells and was restricted by a major histocompatibility complex class II gene product. A specific anti-GP-10/20 T-cell line was established, and it was able to transfer a delayed-type hypersensitivity (DTH) response to normal mice. Both antigens were also recognized during an ongoing disease, as assessed by DTH response of infected mice. By this response, it was possible to distinguish susceptible from resistant strains of mice. In the course of the disease in resistant mice a correlation between the size of the primary lesion and the DTH response to GP-10/20 was observed. The presence of the glycoproteins on both promastigote and amastigote forms of the parasite, the antigenic similarities between both fractions, and the distribution of the GP-10/20 antigen in other trypanosomatids were studied. The results showed that both antigens were present on promastigotes and amastigotes. GP-10/20 shared no epitopes with FR II Phe, was included as part of the crude preparation leishmanin, and had some cross-reactive determinants with Leishmania donovani and Crithidia deanei.

Characterization of the in vitro murine T-cell proliferative responses to murine and human thyroglobulins in thyroiditis-susceptible and -resistant mice

The in vitro proliferative response to autoantigenic mouse thyroglobulin (MTg) of lymph node cells (LNC) from thyroiditis-susceptible (high-responder) CBA/J ( H-2 k ) mice was further characterized. The relatively weak response was enhanced by adding irradiated spleen cells from normal syngeneic mice to cultures of responding LNC. Furthermore, the adjuvant used for immunization was found to influence the magnitude of the response. Results of experiments varying both the adjuvant and the route of immunization (footpad versus subcutaneous) demonstrated that marked proliferative response to MTg in vitro was not necessarily a predictor of the severity of disease. However, the capacity to proliferate in response to MTg correlated with disease susceptibility, as reported previously. The response to MTg was dependent on Thy-1 +, Lyt-1 +2 − cells and was inhibited by monoclonal I-A antibodies. Thus, proliferation is mediated by T cells of the helper/amplifier phenotype recognizing the autoantigen in association with Ia molecules. The determinants on human thyroglobulin (HTg) and MTg stimulating the proliferative responses of LNC from thyroiditis-susceptible and thyroiditis-resistant (low-responder) BALB/c ( H-2 d ) mice were found to differ. Cells from resistant mice proliferated only in response to foreign determinants on HTg and not to shared or mouse-specific epitopes of MTg, whereas susceptible mice had T cells reactive to shared determinants expressed on MTg and HTg as well as to foreign determinants on HTg.

B-CLL cell surface markers and mitogen-induced thymidine uptake: a comparison between lymph node cells and peripheral blood lymphocytes in 25 patients.

Lymphocytes from peripheral blood and lymph nodes from 25 patients with B-CLL were analysed by immunofluorescent staining of surface membrane immunoglobulin (SmIg), the B-cell marker B1, and the T-cell markers Leu 1/2/3/4. Tritium-thymidine uptake was measured in mitogen-stimulated 4-day cultures. Differences in these parameters between cells from the two sources in each patient were calculated with the paired T-test. All cell samples showed a clonal B-cell population. More blood lymphocytes than lymph node cells expressed the monoclonal SmIg (mu or gamma, p = 0.04; kappa or lambda, p less than 0.01), and T-cells were more frequent in lymph nodes (p = 0.01), where the T helper/suppressor ratio was higher. Furthermore, lymph node cells showed a higher thymidine uptake in response to the mitogens LPS, PWM, and Cowan (p = 0.01, p = 0.01, and p = 0.004, respectively), but there was no difference in the responses to EBV, DxS, TPA and PHA (p greater than 0.5). The higher response in lymph node cells to some mitogens might in part be explained by differences in the numbers of accessory cells, such as T-helper cells, but also by the existence of leukaemic B-cell subsets with different mitogen response patterns and different distributions within the lymphoid compartments. The characterization of subsets within a malignant cell clone might be of clinical importance.