Parvum Treatment Research Articles

Up-regulation of inducible nitric oxide synthase expression in cancer-prone p53 knockout mice.

High concentrations of nitric oxide (NO) cause DNA damage and apoptosis in many cell types. Thus, regulation of NO synthase (NOS) activity is essential for minimizing effects of cytotoxic and genotoxic nitrogen oxide species. We have shown previously that NO-induced p53 protein accumulation down-regulates basal and cytokine-modulated inducible NOS (NOS2) expression in human cells in vitro. To further characterize the feedback loop between NOS2 and p53, we have investigated NO production, i.e., urinary nitrate plus nitrite excretion, and NOS2 expression in homozygous p53 knockout (KO) mice. We report here that untreated p53 KO mice excreted 70% more nitrite plus nitrate than mice with wild-type (wt) p53. NOS2 protein expression was constitutively detected in the spleen of untreated p53 KO mice, whereas it was undetectable in the spleen of wt p53 controls. Upon treatment with heat-inactivated Corynebacterium parvum, urinary nitrite plus nitrate excretion of p53 KO mice exceeded that of wt controls by approximately 200%. C. parvum treatment also induced p53 accumulation in the liver. Splenectomy reduced the NO output of C. parvum-treated p53 KO mice but not of wt p53 controls. Although NO production and NOS2 protein expression were increased similarly in KO and wt p53 mice 10 days after injection of C. parvum, NOS2 expression returned to baseline levels only in wt p53 controls while remaining up-regulated in p53 KO mice. These genetic and functional data indicate that p53 is an important transrepressor of NOS2 expression in vivo and attenuates excessive NO production in a regulatory negative feedback loop.

Nitric oxide and prostaglandins interact to prevent hepatic damage during murine endotoxemia.

Nitric oxide (NO) and prostaglandins (PG) both possess the ability to induce vasodilatation and prevent the aggregation of platelets. The synthesis of these substances is increased following in vivo lipopolysaccharide (LPS) infusion, but their function during sepsis is incompletely understood. We studied the role of NO and PG in a murine model of chronic hepatic inflammation (Corynebacterium parvum injection), which is known to progress to sudden hepatic necrosis after LPS injection. NO synthesis, which is induced in hepatocytes by C. parvum treatment and in nonparenchymal cells by LPS treatment, was inhibited using NG-monomethyl-L-arginine (L-NMMA). High-dose aspirin (ASA) was used to block PG synthesis. Treatment with L-NMMA or ASA alone, in the absence of LPS, resulted in no increase in hepatic injury. C. parvum-treated mice that received both L-NMMA and ASA without LPS developed marked hepatic damage as reflected by increased hepatocellular enzyme release (aspartate aminotransferase and L-ornithine carbamoyl-transferase). Marked hepatic damage was seen after LPS administration, and ASA pretreatment alone had no effect on the LPS-induced hepatic injury, whereas L-NMMA markedly increased the hepatic damage. The combination of L-NMMA and ASA after LPS resulted in the greatest hepatocellular enzyme release, characterized histologically by intravascular thrombosis with diffuse infarction and necrosis. Simultaneous treatment with either PGI2 or L-arginine partially prevented this injury. These data demonstrate that NO and PG function synergistically to maintain hepatocellular integrity; thus increased synthesis of these mediators protects the liver from the pathophysiological effects of LPS in this model.

Splenomimetic effect of Corynebacterium parvum in fulminant pneumococcemia.

The efficacy of Corynebacterium parvum to stimulate splenic growth and to boost host survival was examined by using adult Sprague-Dawley rats in a highly spleen-sensitive model of fulminant pneumococcemia. Rats were either treated (10 days or 1 hr before or 1 hr after) or not treated with C. parvum; were depleted of complement; underwent partial, total, or sham splenic resection; and then were challenged with either a low (2 X 10(2)) or a high (2 X 10(5)) dose of pneumococci. In the absence of C. parvum, survival (percent and duration) was lowest after total splenectomy and was proportional to remnant spleen weight after partial splenectomy. Although C. parvum treatment sharply increased splenic weight, nucleated cell numbers, and survival, the lowered mortality and improved survival time were independent of spleen weight. The rapidly acting, extrasplenic, splenomimetic protective effect of C. parvum suggests that this class of immunomodulators may be a useful adjunct in managing sepsis associated with defective or absent splenic function.

The effect of in vivo modulation of macrophage activities on Mycobacterium lepraemurium infection

During the early stage of Mycobacterium lepraemurium (MLM) infection in mice, the mononuclear phagocyte system (MPS) was activated non-specifically as demonstrated by enhanced listericidal activity. Such listericidal activity could be further increased by Corynebacterium parvum treatment, indicating that MLM was not a good MPS stimulant. Corynebacterium parvum treatment conferred only marginal protection upon mice during MLM infection, as shown by the slight but significant prolongation of survival time and decreased bacillary load. In contrast, mice could not control splenic Listeria growth in the later stage of infection regardless of C. parvum treatment. Adoptive transfer of Listeria-immune spleen lymphocytes, however, did significantly suppress splenic Listeria growth. The significance of these findings is discussed.

Role of T-Cell Subsets in the Destruction of Established Metastases of 13762A Rat Mammary Adenocarcinoma<xref ref-type="fn" rid="FN1">2</xref>

The 13762A rat mammary adenocarcinoma metastasizes with high frequency to regional lymph nodes and lungs. The intratumoral injection of Corynebacterium parvum on day 7 followed by primary tumor excision on day 20 significantly prolonged survival and cured 10-40% of syngeneic F344 rats. Established metastases were destroyed by the treatment, and strong and specific tumor rejection immunity was induced. The purpose of the present study was to determine if T-cells were required for the C. parvum treatment to be effective and to identify the subsets of T-lymphocytes that might participate in the response. The results indicated that rats depleted by either neonatal thymectomy or a combination of adult thymectomy, 900 rad, and bone marrow reconstitution did not inhibit tumor growth after C. parvum treatment. Restoration of depleted rats with lymph node cells permitted effective treatment. The lymph node cells that were responsible for restoration expressed both W3/13 (pan-T-cell) and W3/25 (helper T-cell) membrane-associated differentiation antigens. T-cells that bore the MRC OX8 (cytotoxic-suppressor T-cell) antigen did not restore the response to C. parvum treatment. The effect of lymph node restoration was markedly potentiated by simultaneous administration of thymocytes, a T-cell population that expresses both W3/25 and MRC OX8 antigens. In conclusion, the cytotoxic-suppressor T-cells were ineffective in the restoration of T-cell-depleted, tumor-bearing rats to benefit from C. parvum but helper T-cells were highly effective, and their activity was strongly potentiated by administration of thymocyte amplifier cells.

BCG, in contrast to C. parvum, does not induce increased sensitivity to the toxic effects of indomethacin in mice.

Treatment of mice with killed Corynebacterium parvum (also designated Propionibacterium acnes, P. acnes) or Bacille Calmette Guerin (BCG) leads to modification of several of the same host systems. However, BCG, in contrast to C. parvum, did not induce increased sensitivity to the toxic effects of indomethacin in BALB/c or C57B1/6 mice. In addition, treatment of mice with BCG did not interfere with the induction of sensitivity by C. parvum. Therefore C. parvum must uniquely induce changes in host systems which alter the sensitivity to this anti-inflammatory drug. Additional experiments with splenectomized animals revealed that the presence of this organ, which undergoes hypertrophy following C. parvum treatment, was not necessary for the induction of indomethacin sensitivity. Presentation of C. parvum via the subcutaneous route versus the intraperitoneal route revealed that the two routes were equally efficient in inducing sensitivity in C57B1/6 mice but the former route was less effective (50% deaths) than the intraperitoneal route (95% deaths) in BALB/c mice. These results indicate that host related factors (genetic) may be important in the generation of enhanced sensitivity to the toxic effects of indomethacin.

Splenocytes from tumor-bearing Corynebacterium parvum treated mice maintain interleukin-2 and -3 activity.

Systemic and local administration of the bacterium Corynebacterium parvum (more accurately known as Propionibacterium acnes) is reported to exert antitumor action via activated macrophages or short-lived cytotoxic T lymphocytes (CTL), respectively. This study examined the effect of C. parvum treatment on resulting in vitro interleukin levels, which are components in the sequence of events leading to the development of effective CTL. C. parvum administration prevented palpable fibrosarcoma development. This was concomitant with restoration and maintenance of normal interleukin-2 (IL-2) and interleukin-3 (IL-3) levels and prevention of suppressor cell development in mice injected with both tumor cells and vaccine. Our finding of C. parvum-induced maintenance of IL-2 and IL-3 levels and apparent lack of suppressor cell formation lends support to the idea of local C. parvum antitumor action possibly being mediated by CTL arising via the interleukin cascade.

The effect of combination treatment with alpha-difluoromethylornithine and Corynebacterium parvum on B16 melanoma growth and tumoricidal effector cell generation in vivo.

The objective of the present investigation was to establish whether a known lymphoreticular-stimulating agent Corynebacterium parvum would augment the established antitumor activity of alpha-difluoromethylornithine in vivo. Furthermore, since C. parvum is known to boost cell mediated cytotoxicity, the effect of DFMO (DL-alpha-difluoromethylornithine X HCl X H2O) treatment was evaluated on macrophage and natural killer (NK) cell tumoricidal activity. DFMO administered alone, 1% or 2% in drinking water, inhibited 49.4% or 88.0% of B16 melanoma growth in vivo, respectively. Administration of C. parvum alone, three doses of 300 micrograms each, inhibited tumor growth 57.4%. When administered together, DFMO and C. parvum treatment resulted in 89.8% (1% DFMO) or 97.4% (2% DFMO) inhibition of melanoma growth depending upon the dose of DFMO. C. parvum-treated animals had increased levels of macrophage-mediated tumoricidal activity directed against B16 melanoma cells in vitro, however, NK cell activity was reduced. DFMO treatment alone had no effect on macrophage or NK cell tumoricidal activity. In animals receiving both C. parvum and DFMO treatments macrophage-mediated tumoricidal activity was augmented. These results demonstrate that C. parvum can augment the antitumor activity of DFMO in vivo, possibly through macrophage activation. Furthermore, in contrast to many other cancer chemotherapeutic drugs, DFMO is apparently not immunosuppressive regarding tumoricidal effector cells.

Immunologic Control of a Retrovirus-Associated Murine Adenocarcinoma. VI. Augmentation of Antibody-Dependent Killing Following Quantitative and Qualitative Changes in Host Peritoneal Cells<xref ref-type="fn" rid="FN1">2</xref><xref ref-type="fn" rid="FN2">3</xref>

Attempts were made to augment the antibody-dependent killing of the ascitic AD755a tumor in vivo to protect C57BL/6J mice against the outgrowth of larger tumor burdens. The lethal dose for this tumor is less than 100 cells, and antibodies contained in a hyperimmune antitumor serum (HIS) were found to suppress the outgrowth of a maximum of about 5 X 10(5) cells. Thioglycollate injected ip increased the number of peritoneal macrophages, potential effectors for antibody-dependent cell-mediated cytotoxicity (ADCC), by tenfold to fortyfold and raised the maximum treatable tumor challenge (MTTC) to about 4 X 10(6) cells. By comparison, ip injection of Corynebacterium parvum increased the total peritoneal cell population by only twofold but raised the MTTC to about 20 X 10(6) cells. Neither agent alone had an effect on long-term survival, even at very low tumor inocula (1 X 10(3) cells). The protective HIS is known to contain tumor-binding antibodies in each of the IgG1, IgG2A, and IgG2B isotype fractions. Although the IgG2A fraction is far superior in vivo in the suppression of tumor outgrowth, the IgG2A fraction was also found to be most effective in combination with thioglycollate treatment in agreement with the observed preference of thioglycollate-elicited macrophages for this isotype in in vitro killing assays. In contrast following C. parvum treatment, all three isoptype fractions were equally suppressive to tumor outgrowth. A second major change following C. parvum treatment was that tumor cells precoated in vitro with antibodies were effectively eliminated in vivo. The same antibody-coated cells administered to thioglycollate-treated or unmanipulated animals were uniformly lethal even at much lower tumor doses. Taken together these results suggested a major qualitative change in the antibody-dependent tumor-killing process following C. parvum treatment. This change was most likely due to the C. parvum activation of highly lytic effector cells for ADCC, the identity of which was examined in an accompanying manuscript.

Further experience of Corynebacterium parvum in malignant pleural effusion.

The outcome of drug induced pleurodesis has been evaluated in a non-randomised retrospective study of 67 patients with recurrent malignant pleural effusions treated during 1976-83. Fourteen died within 30 days of treatment. Of the remaining 53 patients, 26 studied during 1976-80 were treated with intrapleural mustine hydrochloride, while 27 studied during 1978-83 were treated with intrapleural Corynebacterium parvum. There was no significant difference between the groups in age, sex, or tumour type, most tumours being secondary to bronchial neoplasms. Corynebacterium parvum successfully prevented reaccumulation of the effusion in 24 (92%) patients, while mustine was effective in only 17 (65%) (p less than 0.05). Data on survival were obtained on 47 cases where a single agent was used to induce pleurodesis. In 25 patients treated with C parvum the mean survival was 251 (range 31-1143) days, compared with 119 (range 31-380) days for the 22 patients in whom mustine was used. Survival of the C parvum group was significantly greater (p less than 0.01). The difference was principally due to the greater number of long term survivors in the C parvum group, nine of this group living for more than 180 days (mean 574, range 180-1143 days) compared with only four such survivors in the mustine group (mean 263, range 193-380 days). This study confirms our initial impression that C parvum is highly effective in controlling recurrent malignant pleural effusions. The finding of unexpected long term survivors with C parvum treatment suggests that this treatment may have an additional effect on the progression of disease, a finding that merits further investigation.

The effect of the immunomodulator corynebacterium parvum on hemisplenectomized mice

The immunomodulator Corynebacterium parvum stimulates the reticuloendothelial system and causes splenic hypertrophy. The ability of C parvum to stimulate splenic regeneration in hemisplenectomized mice and decrease susceptibility to intranasal pneumococcal challenge was studied. Mice were divided into two groups, control sham-operated (n = 48) and hemisplenectomized (n = 47) animals. Ten days later, each group was divided into two subgroups, those injected with C parvum (700 mcg IVP) and those injected with an equivalent volume of saline. The animals were challenged with Streptococcus pneumoniae, which was injected into one nostril three weeks postoperatively, and mortality was assessed. Four and one-half weeks postoperatively, splenic tissue was removed, measured, weighed, and submitted for histologic examination. The number of spleen cells per gram of tissue was assessed. Treatment with C parvum resulted in a significant increase in the splenic weight in both hemisplenectomized and control animals compared to similar saline-injected mice (P less than 0.001). The percentage increase in spleen weight of hemisplenectomized mice (106%) was significantly greater than that for control animals (56%; P less than 0.01). There was no significant difference among experimental groups in the number of spleen cells per gram of splenic tissue or in the histologic characteristics, indicating that C parvum stimulated relatively normal splenic growth. Survival following pneumococcal challenge was significantly increased for hemisplenectomized mice by C parvum treatment to a level that did not significantly differ from control mice. This study demonstrates that in mice the deficits related to resistance to infection and spleen size following hemisplenectomy are significantly improved by treatment with C parvum.

Macrophages as effector cells of protective immunity in murine schistosomiasis. V. Variation in macrophage schistosomulacidal and tumoricidal activities among mouse strains and correlation with resistance to reinfection.

Mice of several inbred strains previously characterized as defective in various aspects of macrophage activation for tumor cell killing were utilized to compare the genetic control of induction of macrophage tumoricidal and schistosomulacidal activity and to examine the role of activated macrophages in concomitant immunity to Schistosoma mansoni infection. In all mouse strains tested, macrophage larvicidal activity developed concurrently with tumoricidal activity after in vivo bacillus Calmette Guérin or Corynebacterium parvum treatment. Lpsd strains, A/J, and P/N mice failed to develop macrophages capable of killing either tumor cells or helminth larvae in vitro, whereas C57BL/6J, C3H/HeN, and BALB/c mice all demonstrated strongly cytotoxic cells. In fact, analysis of the reactivity of peritoneal cells from C. parvum-treated F1 hybrids between H-2 congeneic high responder (B10.A) and low responder (A) strains of mice, as well as from F1 hybrid X parent backcross animals, suggested that macrophage activation for killing of these two unrelated extracellular targets is controlled by the same autosomal dominant gene. Strains of mice that failed to develop activated macrophages after in vivo treatment with bacterial stimuli also failed to develop tumoricidal and larvicidal macrophages as a result of S. mansoni infection. The addition of antischistosome sera to the cultures did not reverse the unresponsiveness of macrophages from S. mansoni-infected C3H/HeJ, A/J, or P/N mice in in vitro larvicidal assays. Furthermore, the pattern of concomitant immunity at 6 wk after primary S. mansoni infection correlated closely with the pattern of induction of activated macrophages in these strains of mice. Whereas animals with normal macrophage function developed highly significant levels of concomitant immunity, strains with the Lps defect demonstrated lower levels of acquired resistance, and A/J and P/N mice were not significantly resistant to S. mansoni challenge infection. These results indicate that the genes controlling macrophage activation for the killing of extracellular targets also influence the development of concomitant immunity in schistosomiasis, and suggest that macrophages activated as a consequence of primary S. mansoni infection may be involved in the in vivo effector mechanism of resistance to challenge infection.

Investigation of effects of some immunoadjuvants and routes of antigen administration in raising antibodies in rabbits against metacestode cyst antigens of taenia multiceps

The relative efficiency of depot (Freund's complete adjuvant (FCA) and saponin), and non-depot ( Corynebacterium parvum strain P. acnes I, C. parvum strain IMI585, and levamisole) immunoadjuvants were compared in raising agglutinating and precipitating antibodies against the metacestode fluid of Taenia multiceps of sheep origin (TMCF). Haemagglutinating but not precipitating antibodies were detectable during the period of primary immunisation. Precipitating antibodies of higher titre were produced for longer when TMCF was injected with immunoadjuvant than when the same volume of TMCF was injected alone. Significantly ( P < 0.05) higher indirect haemagglutination (IHA) titres were produced during the primary response following C. parvum treatment than after FCA treatment. FCA treated rabbits showed significantly ( P < 0.05) higher IHA titres than those receiving C. parvum treatment on day 42 only, during the anamnestic response. Ulcers formed at the sites of injection of depot immunoadjuvants. Significantly ( P < 0.05) higher IHA titres were produced when FCA with TMCF was injected intradermally into 10–12 sites than when the same volume was injected into 4 sites. C. parvum strain IM1585 was a better immunoadjuvant in this system than the strain P. acnes I. The intravenous route of administration yielded better titres than the intraperitoneal route when C. parvum strain P. acnes I was used.

Protection of mice against influenza virus infection: Enhancement of nonspecific cellular responses by Corynebacterium parvum

Groups of C57Bl/6J, BALB/c, BALB/c nu +/nu + mice, inoculated intranasally with Corynebacterium parvum (350 μg/mouse) were protected from death by an otherwise lethal dose of influenza virus, A/WSN (H1N1) inoculated 3 days later. The lungs of C. parvum-trented, virus-infected C57Bl/6J, BALB/c, or BALB/c nu +/nu + mice contained significantly less infectious virus than did controls, and this reduction was apparent as soon as 24 hr after virus inoculation. The maximum protective effect correlated with increased lung interferon levels. C. parvum treatment caused an increase in the lung cell number which was in part due to a large increase (ca. 10-fold) in macrophage content, and the natural killer cell activity was also enhanced, though not as markedly as occurred 3 days after infection. Most (>85%) of the resident macrophages in normal lungs were susceptible to infection by virus (as indicated by hemadsorption), whereas most of those recovered from the lungs of C. parvum-treated mice resisted infection. Despite the increase in macrophage content, the level of specific immune responses to infection, such as cytotoxic T-cell activity, DTH reaction, and antihemagglutinin antibody, remained unchanged by C. parvum treatment so that the major if not only effect of this treatment was on the level of the less-specific components of the immune system.

Enhanced Fc receptor expression by a sub-population of murine intra-tumour macrophages following intravenous Corynebacterium parvum therapy.

Intravenous injection of Corynebacterium parvum (C. parvum) 4 days after s.c. inoculation of 5 X 10(5) cells derived from the immunogenic fibrosarcoma FSA/R induced tumour growth inhibition over a period of 21 days in syngeneic C3H/Buf mice. This was not accompanied by a change in the proportions of host cells within the tumour, but the activation state of tumour-infiltrating macrophages was increased following C. parvum therapy. Two macrophage subpopulations were identified in FSA/R tumours after fractionation by unit gravity velocity sedimentation. After i.v. C. parvum therapy the tumour-infiltrating macrophage subpopulation which sedimented between 1 and 6 mm h-1 was consistently activated as determined by measurement of Fc receptor avidity. Other intra-tumour macrophages were generally unaffected by C. parvum treatment. We have previously shown that the host cell fraction sedimenting between 1 and 6 mm h-1 is enriched with monocytes and the data presented in this paper suggest that these cells may enter the tumour in a pre-activated state following intravenous C. parvum therapy.

Inhibition of hepatic drug metabolism in the rat after Corynebacterium parvum treatment

Drug-metabolizing enzyme activities, cytochrome concentration, and protein content of hepatic microsomal preparations from adult, female Sprague-Dawley rats were examined at 1-, 3-, 6-, 10-, 14- and 17-day intervals after administration of a single intravenous injection of Corynebacterium parvum ( C. parvum) at a dose of 10 mg/m 2. Aniline hydroxylase (AH) activity, aminopyrine demethylase (APD) activity, and cytochrome P-450 concentration were reduced 20–50% on days 3–6 and, thereafter, gradually recovered to control levels by day 17. Cytochrome c reductase activity and cytochrome b 5 concentration were reduced significantly (24%) only on day 10. Microsomal protein concentration was unchanged. C. parvum added in vitro had no effect on AH or APD activity. Although livers of treated rats were only slightly (< 20%) enlarged, gross splenomegaly was apparent, reaching a maximum on day 6. A marked inverse correlation existed between the temporal variation in the size of the spleen and APD activity. In rats killed 6 days after administration of C. parvum at 0.67 to 10.00 mg/m 2, a direct relationship was apparent between the adjuvant dose and the magnitude of reduction of APD activity. A similar relationship was apparent between splenomegaly and APD activity. Histopathologic examination of liver sections from treated rats revealed numerous granulomas throughout the parenchyma. The magnitude of enzyme inhibition generally paralleled the severity of the hepatic lesions.

Improved survival after pneumococcus in splenectomized and nonsplenectomized mice with Corynebacterium parvum.

Splenectomy increases the susceptibility to infections with certain bacteria, particularly Streptococcus pneumoniae. Because the immunomodulator Corynebacterium parvum expands the phagocytic cell compartment and enhances reticuloendothelial function, we tested the effect of C parvum in mice challenged with aerosolized pneumococci. Mice splenectomized seven days before pneumococcal challenge and treated intraperitoneally with 700 micrograms of C parvum immediately after exposure were protected when compared with splenectomized or sham-operated saline-injected controls. Analysis of proportional hazards showed the risk of dying in order of greatest to least as follows: splenectomy/saline, sham/saline, splenectomy/C parvum and sham/C parvum. The benefits of an intact spleen and C parvum seemed to be additive in their protective effects after aerosol pneumococcal challenge. After intravenous challenge, bloodstream clearance was improved in sham-operated mice at three days after C parvum injection compared with saline-injected sham-operated controls and C parvum-injected splenectomized mice. A significant improvement in bacterial clearance did not occur until seven days after C parvum treatment in splenectomized mice. The results demonstrate the value of a nonspecific immunomodulator for enhancing the defense mechanisms of both normal and splenectomized animals.

Accessory Cell Function in Tumor-Bearing Mice and Effects of &lt;italic&gt;Corynebacterium parvum&lt;/italic&gt;&lt;xref ref-type="fn" rid="FN2"&gt;2&lt;/xref&gt;&lt;xref ref-type="fn" rid="FN3"&gt;3&lt;/xref&gt;

Primary in vivo production of antibody to sheep red blood cells (SRBC) was consistently suppressed in EL 4 tumor-bearing C57BL/6 mice, but the secondary response was not suppressed. This suppressed primary in vivo production of antibody was partially restored by systemic administration of Corynebacterium parvum. For investigation of the mechanism of the immunosuppression in tumor-bearing mice and the effects of C. parvum, the accessory cell function of adherent cells from tumor-bearing mice and C. parvum-treated tumor-bearing mice in in vitro cultures was studied. Peritoneal and splenic cells from tumor-bearing mice were less efficient in promoting in vitro production of antibody to SRBC by macrophage-depleted normal nonadherent cells than the adherent cells from normal mice. C. parvum treatment restored the accessory cell function of splenic adherent cells from tumor-bearing mice but not that of peritoneal cells. Furthermore, adherent cells from tumor-bearing mice did not show suppressive activity against the in vitro plaque-forming cell response.

Macrophages as effector cells of protective immunity in murine schistosomiasis: IV. Coincident induction of macrophage activation for extracellular killing of schistosomula and tumor cells

Peritoneal macrophages from Schistosoma mansoni-infected mice are activated both for nonspecific tumor cytotoxicity and for killing of skin-stage schistosomula in vitro. In the current study, mechanisms for induction of macrophage tumoricidal and schistosomulacidal activity have been compared. Examination of macrophages activated in vivo by BCG infection or C. parvum treatment, or in vitro by exposure to lymphokine prepared from antigen-stimulated BCG-immune spleen cells, showed that these effector functions were closely linked. Indeed, fractionation of lymphokine-rich supernatant fluids by Sephadex G-100 gel filtraction showed that activities responsible for induction of schistomula killing by inflammatory macrophages and for induction of tumoricidal activity cochromatographed as a single peak in the 50,000 MW region. Thus, development of macrophage-mediated cytotoxicity against these two extracellular (tumor cell or helminth) targets was coincident in several cell populations activated in vivo or in vitro. However, activation for tumoricidal and schistosomulacidal capacity appeared to be quantitatively dissociated in macrophages from mice with chronic schistosomiasis; those cells demonstrated low, yet significant, levels of larval killing ( 1 3 to 1 5 those of BCG or lymphokine-activated cells) but maximal levels of tumor cell cytotoxicity. Furthermore, cytotoxicity by peritoneal cells from S. mansoni-infected mice was not increased in vitro by exposure to lymphokine. Identification of this functional alteration in S. mansoni-activated cells may help to clarify the role of macrophages in the partial immunity against challenge infection which is demonstrated by mice with chronic primary S. mansoni infection.

Murine Lymph Node Natural Killer Cells: Regulatory Mechanisms of Activation or Suppression23

The kinetics and organ distribution patterns of lymph node natural killer (NK) cell activation or suppression were found to vary according to the type, dose, and route of administration of Corynebacterium parvum or polyinosinic-polycytidylic acid (poly I . poly C). Activation of lymph node NK cells by local injections of C. parvum into the footpad or the peritoneum was restricted to the regional lymph nodes; contralateral and distant lymph nodes were not involved. This selectivity persisted even though splenic and peripheral blood NK cells were strongly activated by the same treatment. Conversely, poly I . poly C induced systemic activation of NK cells without selectively activating the regional lymph nodes. The decline of NK cell activity observed 2 weeks after C. parvum treatment was associated with a state of unresponsiveness to a second injection of NK cell stimulants. The expression of C. parvum-induced suppression could be systemic or restricted to the regional lymph nodes. Possible mechanisms for the anatomical compartmentaliztion of NK cell activation or suppression and the implications for the control of tumor growth and dissemination in vivo are discussed.