Quantifying the magnetic advantage in magnetotaxis

Magnetotactic bacteria are characterized by the production of magnetosomes, nanoscale particles of lipid bilayer encapsulated magnetite, that act to orient the bacteria in magnetic fields. These magnetosomes allow magneto-aerotaxis, which is the motion of the bacteria along a magnetic field and toward preferred concentrations of oxygen. Magneto-aerotaxis has been shown to direct the motion of these bacteria downward toward sediments and microaerobic environments favorable for growth. Herein, we compare the magneto-aerotaxis of wild-type, magnetic Magnetospirillum magneticum AMB-1 with a nonmagnetic mutant we have engineered. Using an applied magnetic field and an advancing oxygen gradient, we have quantified the magnetic advantage in magneto-aerotaxis as a more rapid migration to preferred oxygen levels. Magnetic, wild-type cells swimming in an applied magnetic field more quickly migrate away from the advancing oxygen than either wild-type cells in a zero field or the nonmagnetic cells in any field. We find that the responses of the magnetic and mutant strains are well described by a relatively simple analytical model, an analysis of which indicates that the key benefit of magnetotaxis is an enhancement of a bacterium's ability to detect oxygen, not an increase in its average speed moving away from high oxygen concentrations.

Inflammation and clearance of Chlamydia trachomatis in enteric and nonenteric mucosae

Immunization(s) fostering the induction of genital mucosa-targeted immune effectors is the goal of vaccines against sexually transmitted diseases. However, it is uncertain whether vaccine administration should be based on the current assumptions about the common mucosal immune system. We investigated the relationship between mucosal sites of infection, infection-induced inflammation, and immune-mediated bacterial clearance in mice using the epitheliotropic pathogen Chlamydia trachomatis. Chlamydial infection of the conjunctival, pulmonary, or genital mucosae stimulated significant changes in tissue architecture with dramatic up-regulation of the vascular addressin, VCAM, a vigorous mixed-cell inflammatory response with an influx of alpha4beta1+ T cells, and clearance of bacteria within 30 days. Conversely, intestinal mucosa infection was physiologically inapparent, with no change in expression of the local MAdCAM addressin, no VCAM induction, no histologically detectable inflammation, and no tissue pathology. Microbial clearance was complete within 60 days in the small intestine but bacterial titers remained at high levels for at least 8 months in the large intestine. These findings are compatible with the notion that VCAM plays a functional role in recruiting cells to inflammatory foci, and its absence from the intestinal mucosa contributes to immunologic homeostasis at that site. Also, expression of type 1 T cell-mediated immunity to intracellular Chlamydia may exhibit tissue-specific variation, with the rate and possibly the mechanism(s) of clearance differing between enteric and nonenteric mucosae. The implications of these data for the common mucosal immune system and the delivery of vaccines against mucosal pathogens are discussed.

Crossreactive neutralizing antibodies induced by immunization with caprine arthritis-encephalitis virus surface glycoprotein

Four Saanen goats were immunized with affinity purified gp135 surface glycoprotein (SU) of caprine arthritis-encephalitis virus isolate 79-63 (CAEV-63) and evaluated for homologous and crossreactive serum neutralizing antibodies. CAEV-63 neutralizing antibodies were detected in all goats after seven immunizations with SU in Quil A adjuvant. Sera from three goats neutralized an independent CAEV isolate (CAEV-Co). However, serum from one goat did not detectably neutralize heterologous CAEV-Co and inhibited CAEV-Co neutralization by another serum.

Chlamydial colonization of multiple mucosae following infection by any mucosal route

Chlamydia trachomatis inoculated by any mucosal route colonized multiple murine mucosae and, in most cases, the spleen, liver, and kidneys. Cell-to-cell transmission, systemic dissemination, and autoinoculation of infectious fluids may have contributed to chlamydial spread. Intermucosal trafficking of protective T cells cannot be accurately evaluated by using live chlamydial challenges.

Differential sensitivity of distinct Chlamydia trachomatis isolates to IFN-gamma-mediated inhibition

Resistance to the mouse pneumonitis (MoPn) strain of Chlamydia trachomatis has been mapped to MHC class II-restricted, IL-12-dependent CD4+ T cells that secrete a type 1 profile of proinflammatory cytokines, which includes IFN-gamma and TNF-alpha. The relative contribution of IFN-gamma is controversial, however, due to variation in results presented by different laboratories. To determine whether C. trachomatis strain differences contributed to this apparent conflict, the relative resistance of IFN-gamma-deficient mice to murine and human strains of C. trachomatis was compared. All human serovars were much more sensitive to the direct inhibitory actions of IFN-gamma than the MoPn strain. Furthermore, genital clearance of human serovar D in the C57BL/6 mouse was mediated by class II-independent mechanisms that probably involved local production of IFN-gamma by cells of the innate immune system. TNF-alpha also contributed indirectly to host resistance against all strains tested. The differential susceptibility of distinct C. trachomatis strains to effector cytokines such as IFN-gamma could not have been predicted by interstrain biologic variation or by the profile of cytokines stimulated during infection. These findings indicate that strain variation should be considered in situations where related isolates of a given parasite produce conflicting data in models of infection and immunity. They also suggest that stimulation of mucosal IFN-gamma activity is a relevant goal for a human chlamydial vaccine.

Clearance of Chlamydia trachomatis from the murine genital mucosa does not require perforin-mediated cytolysis or Fas-mediated apoptosis

The molecular mechanisms of resistance to genital infection with the mouse pneumonitis (MoPn) strain of Chlamydia trachomatis are unknown. A role for major histocompatibility complex class II-restricted, interleukin-12-dependent CD4(+) T cells has been established, but the functional activity of these cells does not depend on secretion of gamma interferon. Here we examined the potential contribution of T-cell-mediated cytotoxicity and apoptosis to mucosal clearance of MoPn by using mice deficient in the molecular mediators of target cell lysis. Animals lacking perforin, Fas, Fas ligand, or both perforin and Fas ligand were infected genitally with C. trachomatis MoPn and monitored for expression of immunity to chlamydial antigens and clearance of MoPn from the genital mucosa. In each case, the profile of spleen cytokine production, the magnitude of the host antibody response, and the kinetics of chlamydial clearance were similar to those of genetically intact controls. Compensatory overproduction of tumor necrosis factor alpha, an alternate mediator of apoptosis in certain cell types, did not appear to account for the ability of mutant mice to resolve Chlamydia infections. These results fail to support CD4(+) T-cell-mediated apoptosis or CD8(+) T-cell-mediated cytotoxicity as being critical to the clearance of C. trachomatis MoPn urogenital infections.

Chlamydial infection in inducible nitric oxide synthase knockout mice

Type 1 CD4+-T-cell-mediated immunity is crucial for the resolution of chlamydial infection of the murine female genital tract. Previous studies demonstrating a correlation between CD4+-T-cell-mediated inhibition of chlamydial growth and gamma interferon (IFN-gamma)-mediated induction of nitric oxide synthase suggested a potential role for the nitric oxide (NO) effector pathway in the clearance of Chlamydia from genital epithelial cells by the immune system. To clarify the role of this pathway, the growth levels of Chlamydia trachomatis organisms in normal (iNOS+/+) mice and in genetically engineered mice lacking the inducible nitric oxide synthase (iNOS) gene (iNOS-/- mice) were compared. There was no significant difference in the course of genital chlamydial infections in iNOS+/+ and iNOS-/- mice as determined by recovery of Chlamydia organisms shed from genital epithelial cells. Dissemination of Chlamydia to the spleen and lungs occurred to a greater extent in iNOS-/- than in iNOS+/+ mice, which correlated with a marginal increase in the susceptibility of macrophages from iNOS-/- mice to chlamydial infection in vitro. However, infections were rapidly cleared from all affected tissues, with no clinical signs of disease. The finding of minimal dissemination in iNOS-/- mice suggested that activation of the iNOS effector pathway was not the primary target of IFN-gamma during CD4+-T-cell-mediated control of chlamydial growth in macrophages because previous reports demonstrated extensive and often fatal dissemination of Chlamydia in mice lacking IFN-gamma. In summary, these results indicate that the iNOS effector pathway is not required for elimination of Chlamydia from epithelial cells lining the female genital tract of mice although it may contribute to the control of dissemination of C. trachomatis by infected macrophages.

Distinct homing pathways direct T lymphocytes to the genital and intestinal mucosae in Chlamydia-infected mice

Immunity to genital tract infection with Chlamydia trachomatis is mediated by type 1 CD4+ T lymphocytes. To define the signals that govern lymphocyte trafficking to the genital mucosa, integrins expressed by infiltrating T cells and endothelial addressins displayed on local vasculature were characterized during the course of infection. All T cells expressed the alphaLbeta2 heterodimer that binds vascular ICAM-1, and most displayed enhanced levels of the alpha4beta1 integrin that interacts with VCAM-1. AlphaE and beta7(low) integrin chains were detected on approximately 15 and 30% of infiltrating T cells, respectively. Lymphocytes derived from the spleen or draining lymph nodes expressed this same integrin profile, suggesting that cells are recruited to the genital mucosa from the systemic circulation without significant selection pressure for these markers. Immunofluorescent staining for the corresponding vascular addressins revealed intense expression of VCAM-1 on small vessels within Chlamydia-infected genital tracts and up-regulation of ICAM-1 on endothelial, stromal, and epithelial cells. Mucosal addressin cell adhesion molecule-1 was not detected within genital tissues. These results indicate that T lymphocyte homing to the genital mucosa requires the interaction of alphaLbeta2 and alpha4beta1 with endothelial ICAM-1 and VCAM-1, respectively, which is the same pathway that directs lymphocytes to systemic sites of inflammation. Homing pathways defined for the intestinal mucosa and assumed to be relevant to all mucosal sites are not well represented in the genital tract. The identification of T lymphocyte trafficking pathways shared between systemic and mucosal tissues should facilitate vaccine strategies aimed at maximizing immune responses against Chlamydia and other pathogens of the urogenital tract.

Neither interleukin-6 nor inducible nitric oxide synthase is required for clearance of Chlamydia trachomatis from the murine genital tract epithelium

Female mice bearing targeted mutations in the interleukin-6 or inducible nitric oxide synthase locus mounted effective immune responses following vaginal infection with Chlamydia trachomatis. Chlamydial clearance rates, local Th1 cytokine production, and host antibody responses were similar to those of immunocompetent control mice. Therefore, neither gene product appears to be critical for the resolution of chlamydial infections of the urogenital epithelium.

Immunity to Chlamydia trachomatis is mediated by T helper 1 cells through IFN-gamma-dependent and -independent pathways

Mucosal immunity to Chlamydia trachomatis in a mouse model of female genital tract infection is mediated predominantly by Th1-type cells, as shown by in vivo neutralization of cytokines involved in the Th1 vs Th2 pathways. Neutralization of IL-12 was associated with an apparent decrease in the infiltration of CD4+ T cells into infected tissues, systemic reductions in the production of IFN-gamma, and prolonged shedding of high levels of bacteria. Neutralization of IL-4 had no detectable effect on host immunity or on bacterial clearance. To dissociate the protective role of IL-12 from that of IL-12-induced IFN-gamma, resistance to C. trachomatis was compared in IL-12-depleted and IFN-gamma-deficient animals. IL-12-depleted mice displayed minimal bacterial clearance for 1 mo post-infection but eventually resolved genital tract infections completely. IFN-gamma-deficient mice, on the other hand, cleared 99.9% of genital Chlamydia within the first 3 wk but then developed systemic disease associated with dissemination of bacteria to multiple organs. Animals surviving this stage often maintained low level persistent infections within the urogenital tract. These results indicate that the bulk of chlamydial clearance from the genital mucosa is mediated by an IL-12-dependent, IFN-gamma-independent mechanism, while prevention of disseminated disease requires the action of IFN-gamma.

Immunity to Chlamydia trachomatis is mediated by T helper 1 cells through IFN-gamma-dependent and -independent pathways

Mucosal immunity to Chlamydia trachomatis in a mouse model of female genital tract infection is mediated predominantly by Th1-type cells, as shown by in vivo neutralization of cytokines involved in the Th1 vs Th2 pathways. Neutralization of IL-12 was associated with an apparent decrease in the infiltration of CD4+ T cells into infected tissues, systemic reductions in the production of IFN-gamma, and prolonged shedding of high levels of bacteria. Neutralization of IL-4 had no detectable effect on host immunity or on bacterial clearance. To dissociate the protective role of IL-12 from that of IL-12-induced IFN-gamma, resistance to C. trachomatis was compared in IL-12-depleted and IFN-gamma-deficient animals. IL-12-depleted mice displayed minimal bacterial clearance for 1 mo post-infection but eventually resolved genital tract infections completely. IFN-gamma-deficient mice, on the other hand, cleared 99.9% of genital Chlamydia within the first 3 wk but then developed systemic disease associated with dissemination of bacteria to multiple organs. Animals surviving this stage often maintained low level persistent infections within the urogenital tract. These results indicate that the bulk of chlamydial clearance from the genital mucosa is mediated by an IL-12-dependent, IFN-gamma-independent mechanism, while prevention of disseminated disease requires the action of IFN-gamma.

Depressed CD4+ T lymphocyte proliferative response and enhanced antibody response to viral antigen in chronic lentivirus-induced arthritis

The proliferative response of peripheral blood mononuclear cells (PBMC) stimulated with caprine arthritis-encephalitis virus (CAEV) surface glycoprotein (SU) was depressed 4- to 20-fold in Saanen goats with chronic CAEV-induced arthritis compared with asymptomatic goats. Phytohemagglutinin-stimulated responses were not depressed. Complement depletion of PBMC with anti-CD4 or anti-CD8 monoclonal antibodies identified CD4+ T lymphocytes as the antigen-responsive cells in both high-responder asymptomatic goats and low-responder arthritic goats. Serum antibody titers to CAEV SU were 8- to 32-fold higher in goats with chronic arthritis. Increased anti-CAEV SU titers as early as 3 months after infection predicted the eventual development of clinical arthritis. Thus, CAEV-induced arthritis is associated with chronic B cell activation resulting from dominant type 2 immune responses to viral antigen. The clinical outcome of CAEV infection may be determined by differential activation of type 1 or 2 T lymphocyte phenotypes at or near the time of initial exposure to CAEV.

Contrasting effects from a single major histocompatibility complex class II molecule (H-2E) in recovery from Friend virus leukemia

Resistance to erythroleukemia induced by infection with the Friend virus complex (FV) has been mapped to several genes residing both within and outside the murine major histocompatibility complex (MHC). MHC genes located in the A, D, and Qa/Tla regions of the murine H-2 complex have been shown to affect disease resistance through their capacity to regulate various aspects of the host immune response to viral antigens. This study establishes H-2E as the fourth MHC locus controlling immunological resistance to FV. Our investigation into the role of H-2E molecules revealed two distinct and opposite effects on recovery from Friend disease. H-2b/b mice normally lack a functional E gene product and are resistant to high doses of FV. The expression of H-2E molecules in H-2 recombinant or transgenic mice of this genotype resulted in a significant decrease in spontaneous recovery from FV-induced leukemia. In contrast, H-2E expression also appeared to influence recovery from Friend disease in a positive manner, since blocking these molecules with anti-E antibodies in vivo significantly decreased recovery from Friend disease. The data indicate that the positive effects of H-2E molecules derive from their function as restriction elements for helper T-cell recognition of the viral envelope glycoprotein, and we postulate that the negative effects are due to H-2E-dependent deletion in the T-cell repertoire during development.

Failure of intragastrically administered Yersinia pestis capsular antigen to protect mice against challenge with virulent plague: suppression of fraction 1-specific antibody response

We evaluated the Yersinia pestis capsular (fraction 1 [F1]) antigen as a potential oral immunogen in mice. We found that single doses of as much as 0.4 mg of F1, administered by intragastric (ig) intubation, were unprotective and did not stimulate production of detectable levels of specific antibody. Three weekly ig doses resulted in low serum antibody levels that also did not provide protection against challenge with virulent Y. pestis. Assays of type-specific antibody following intubation and subsequent challenge with a subcutaneous inoculation of F1 revealed that the quantity of antigen intubated and the secondary IgG2a antibody levels were inversely related, suggesting the induction of tolerance to intragastrically administered F1 antigen. Transfer of spleen cells from intubated mice to F1 immune recipients failed to demonstrate suppression of specific antibody, indicating that the immune tolerance observed in intubated mice was not due to a T suppressor cell-mediated effect. The results of this study indicate that Y. pestis F1 antigen is not likely to be an efficacious immunogen for oral vaccination of mice against plague.

T cell sensitization to proteolipid protein in myelin basic protein-induced relapsing experimental allergic encephalomyelitis

(SJL/J x PL/J)F1 mice immunized with myelin basic protein (MBP) develop an autoimmune demyelinating disease termed relapsing experimental allergic encephalomyelitis (rEAE). The acute state of disease is mediated by CD4+ T cells specific for MBP amino acids 1-9. To determine the immunologic bases for disease relapse, host sensitization to additional autoantigens of the central nervous system was measured. Results indicate that most animals develop T cell reactivity to endogenous myelin proteolipid protein (PLP) during rEAE. However, PLP-specific immunity does not appear to account for expression of relapse episodes of demyelination.

Role of CD4+ and CD8+ T cells in murine resistance to street rabies virus

Mice of the SJL/J and BALB/cByJ inbred strains are naturally resistant to street rabies virus (SRV) injected via the intraperitoneal route. To determine the cellular mechanism of resistance, monoclonal antibodies specific for CD4+ or CD8+ subsets of T cells were used to deplete the respective cell population in SRV-infected animals. Elimination of CD4+ T-helper cells abrogated the production of immunoglobulin G (IgG) neutralizing antibodies in response to rabies virus infection and reversed the resistant status of SJL/J and BALB/cByJ mice. In contrast, in vivo depletion of CD8+ cytotoxic T cells had no measurable effect on host resistance to SRV. These results indicate that serum neutralizing antibodies of the IgG class are a primary immunological mechanism of defense against rabies virus infection in this murine model of disease. CD8+ cytotoxic T lymphocytes, which have been shown to transfer protection in other rabies virus systems, appear to have no role in protecting mice against intraperitoneally injected SRV.

Detection of anti-rabies virus cytotoxic T lymphocytes in mice of four distinct H-2 haplotypes using target cells persistently infected with ERA rabies virus

Cells persistently infected with Evelyn-Rokitnicki-Abelseth (ERA) rabies virus were established. The cells were used as stimulator and target cells to compare H-2 restricted cytotoxic T lymphocyte (CTL) responses specific for rabies virus in A/WySnJ (H-2a), C57BL/6J (H-2b), BALB/cByJ (H-2d), A.SW/SnJ (H-2s) and SJL/J (H-2s) mice. Using a 51chromium release assay, it was determined that an effector/target (E/T) ratio of 5:1 was necessary to demonstrate specific lysis of ERA virus persistently infected mouse neuroblastoma (MNB) (H-2a), EL-4 (H-2b) and P815 (H-2d) cells. Effectors at an E:T ratio of only 0.05:1 specifically lysed an SV-40 transformed SJL/J mouse fibroblast (SSSV) (H-2s) target monolayer. The CTL destruction of the SSSV monolayer was observed visually following Giemsa staining. This is the first instance in which a detailed method for detection of murine anti-rabies virus CTLs has been reported. Furthermore, it is the first time target cells persistently infected with rabies virus were used as stimulator cells to amplify CTLs in vitro and as target cells in the CTL assay. It also is the initial report in which rabies specific CTLs were characterized in H-2d and H-2s rabies virus infected mice.

Murine susceptibility to street rabies virus is unrelated to induction of host lymphoid depletion

The mechanism and cellular targets of mononuclear cell depletion were investigated in strains of mice susceptible or resistant to lethal infection with a virulent street rabies virus (SRV). Significant depletion was evident in the thymus of all infected animals at approximately 5 days postinfection and subsequently involved the spleen and lymph nodes in mice developing clinical signs of rabies. Immunofluorescent analyses of lymphocyte subsets in depleted spleens revealed that cell losses were non-selective since the relative proportions of K+, Thy-1+, Lyt-1+, and Lyt-2+ cells remained unchanged. Diminished expression of I-A membrane glycoproteins on spleen lymphocytes was noted, however, perhaps reflecting reduced availability of I-A-inducing lymphokines. Adrenal hormone toxicity was identified as the cause of mononuclear cell depletion in that mice adrenalectomized before SRV infection showed no evidence of lymphoid depletion. The failure of adrenalectomy to alter anti-rabies antibody responses or SRV lethality also indicates that involution of the lymphoid system is a consequence and not a cause of genetically controlled host susceptibility to SRV. The mechanism of adrenal gland stimulation in rabies-infected mice appears to involve a virus-induced dysfunction in the pituitary gland rather than a stress response to paralysis-induced starvation, based on results of kinetic studies on weight loss, appetite depression, and paralysis in these animals and previous reports of pituitary infection during rabies disease. The relationship of these observations to current theories on rabies virus pathogenicity is discussed.

Murine susceptibility to street rabies virus is unrelated to induction of host lymphoid depletion

The mechanism and cellular targets of mononuclear cell depletion were investigated in strains of mice susceptible or resistant to lethal infection with a virulent street rabies virus (SRV). Significant depletion was evident in the thymus of all infected animals at approximately 5 days postinfection and subsequently involved the spleen and lymph nodes in mice developing clinical signs of rabies. Immunofluorescent analyses of lymphocyte subsets in depleted spleens revealed that cell losses were non-selective since the relative proportions of K+, Thy-1+, Lyt-1+, and Lyt-2+ cells remained unchanged. Diminished expression of I-A membrane glycoproteins on spleen lymphocytes was noted, however, perhaps reflecting reduced availability of I-A-inducing lymphokines. Adrenal hormone toxicity was identified as the cause of mononuclear cell depletion in that mice adrenalectomized before SRV infection showed no evidence of lymphoid depletion. The failure of adrenalectomy to alter anti-rabies antibody responses or SRV lethality also indicates that involution of the lymphoid system is a consequence and not a cause of genetically controlled host susceptibility to SRV. The mechanism of adrenal gland stimulation in rabies-infected mice appears to involve a virus-induced dysfunction in the pituitary gland rather than a stress response to paralysis-induced starvation, based on results of kinetic studies on weight loss, appetite depression, and paralysis in these animals and previous reports of pituitary infection during rabies disease. The relationship of these observations to current theories on rabies virus pathogenicity is discussed.

Normal and scrapie-associated forms of prion protein differ in their sensitivities to phospholipase and proteases in intact neuroblastoma cells

Previous studies have indicated that scrapie infection results in the accumulation of a proteinase K-resistant form of an endogenous brain protein generally referred to as prion protein (PrP). The molecular nature of the scrapie-associated modification of PrP accounting for proteinase K resistance is not known. As an approach to understanding the cellular events associated with the PrP modification in brain tissue, we sought to identify proteinase K-resistant PrP (PrP-res) in scrapie-infected neuroblastoma cells in vitro and to compare properties of PrP-res with those of its normal proteinase K-sensitive homolog, PrP-sen. PrP-res was detected by immunoblot in scrapie-infected but not uninfected neuroblastoma clones. Densitometry of immunoblots indicated that there was two- to threefold more PrP-res than PrP-sen in one infected clone. Metabolic labeling and membrane immunofluorescence experiments indicated that PrP-sen was located on the cell surface and could be removed from intact cells by phosphatidylinositol-specific phospholipase C and proteases. In contrast, PrP-res was not removed after reaction with these enzymes. Thus, either the scrapie-associated PrP-res was not on the cell surface or it was there in a form that is resistant to these hydrolytic enzymes. Attempts to detect intracellular PrP-res by immunofluorescent staining of fixed and permeabilized cells revealed that PrP was present in discrete perinuclear Golgi-like structures. However, the staining pattern was similar in both scrapie-infected and uninfected clones, and thus the intracellular staining may have represented only PrP-sen. Analysis of scrapie infectivity in cells treated with extracellular phospholipase, proteinase K, and trypsin indicated that, like PrP-res, the scrapie agent was not removed from the infected cells by any of these enzymes.

Modulation of experimental allergic encephalomyelitis with anti-T suppressor factor antibodies

mAb reactive with T suppressor factors (TsF) were used to alter the course of myelin basic protein-induced experimental allergic encephalomyelitis in (SJL/J x PL/J)F1 mice. In vivo administration of mAb 14-12, reactive with effector TsF, exacerbated the clinical expression of encephalomyelitis as evidenced by prolonged periods of total limb paralysis in affected animals. This aggravation of disease signs is probably related to the inhibition of effector Ts function by mAb 14-12 thus allowing T cell autoreactivity to proceed unchecked. Disease course was influenced more favorably by i.v. administration of mAb 14-30 reactive with a subset of inducer TsF. Ten days of treatment with this mAb resulted in a reduction in the incidence and severity of disease, noted as the development of minimal limb weakness but no paralysis in the majority of affected animals. Adoptive transfer experiments revealed the presence of Ag-specific Ts in mAb 14-30-treated mice that inhibited recipient Lyt-1+ responses to myelin basic protein, the immunizing autoantigen. Suppression by transferred Ts was revealed only by treatment of the donor population with anti-Lyt-1.2 plus C, however, indicating a role for contrasuppressor activity in the regulation of autoimmune T cell function. Results are considered relevant to the potential for immunotherapeutic management of multiple sclerosis in man.

Modulation of experimental allergic encephalomyelitis with anti-T suppressor factor antibodies

mAb reactive with T suppressor factors (TsF) were used to alter the course of myelin basic protein-induced experimental allergic encephalomyelitis in (SJL/J x PL/J)F1 mice. In vivo administration of mAb 14-12, reactive with effector TsF, exacerbated the clinical expression of encephalomyelitis as evidenced by prolonged periods of total limb paralysis in affected animals. This aggravation of disease signs is probably related to the inhibition of effector Ts function by mAb 14-12 thus allowing T cell autoreactivity to proceed unchecked. Disease course was influenced more favorably by i.v. administration of mAb 14-30 reactive with a subset of inducer TsF. Ten days of treatment with this mAb resulted in a reduction in the incidence and severity of disease, noted as the development of minimal limb weakness but no paralysis in the majority of affected animals. Adoptive transfer experiments revealed the presence of Ag-specific Ts in mAb 14-30-treated mice that inhibited recipient Lyt-1+ responses to myelin basic protein, the immunizing autoantigen. Suppression by transferred Ts was revealed only by treatment of the donor population with anti-Lyt-1.2 plus C, however, indicating a role for contrasuppressor activity in the regulation of autoimmune T cell function. Results are considered relevant to the potential for immunotherapeutic management of multiple sclerosis in man.

Kinetics and specificity of T and B cell responses in relapsing experimental allergic encephalomyelitis

T and B cell responses to myelin basic protein (MBP) and its relevant peptide fragments were examined throughout the course of MBP-induced relapsing experimental allergic encephalomyelitis (REAE) in (SJL X PL)F1 mice. T cell reactivity, measured by the antigen-driven proliferation of lymph node T cells in vitro, was directed predominantly against the encephalitogenic MBP-P2 peptide (amino acids 1 to 37) at all stages of disease. Levels of responsiveness did not correlate with disease expression, but declined over time to a relapse level that was four- to sixfold lower than that observed during peak acute stage reactivity. Relapse responses were further distinguished by the detection of host I-E restrictions on Lyt-1+ T cell recognition of P2, P2 recognition by acute-stage T cells occurring solely in the context of host I-A molecules. These data imply an increase in the heterogeneity of relapse T cell responses to MBP to include clones restricted by additional class II glycoproteins. A role for additional CNS autoantigens in the stimulation of relapse T cells is also considered. Serum antibody responses to MBP or the P2 fragment fluctuated randomly throughout R-EAE when total antibody activity (IgM plus IgG) was measured. However, analysis of individual isotypes of IgG immunoglobulins revealed an apparent correlation between peak antigen-binding activity and disease expression which may reflect either an effector or regulatory role for humoral immunity in recurrent EAE. Patterns of early antibody reactivity also distinguished F1 mice that developed or failed to develop disease signs after immunization, the latter exhibiting a consistent drop in antigen-binding activity 4 to 5 days before the usual onset of acute-stage paralysis. The results are considered with regard to possible mechanisms of chronic disease regulation in an environment of functional T cell suppression.

Kinetics and specificity of T and B cell responses in relapsing experimental allergic encephalomyelitis

T and B cell responses to myelin basic protein (MBP) and its relevant peptide fragments were examined throughout the course of MBP-induced relapsing experimental allergic encephalomyelitis (REAE) in (SJL X PL)F1 mice. T cell reactivity, measured by the antigen-driven proliferation of lymph node T cells in vitro, was directed predominantly against the encephalitogenic MBP-P2 peptide (amino acids 1 to 37) at all stages of disease. Levels of responsiveness did not correlate with disease expression, but declined over time to a relapse level that was four- to sixfold lower than that observed during peak acute stage reactivity. Relapse responses were further distinguished by the detection of host I-E restrictions on Lyt-1+ T cell recognition of P2, P2 recognition by acute-stage T cells occurring solely in the context of host I-A molecules. These data imply an increase in the heterogeneity of relapse T cell responses to MBP to include clones restricted by additional class II glycoproteins. A role for additional CNS autoantigens in the stimulation of relapse T cells is also considered. Serum antibody responses to MBP or the P2 fragment fluctuated randomly throughout R-EAE when total antibody activity (IgM plus IgG) was measured. However, analysis of individual isotypes of IgG immunoglobulins revealed an apparent correlation between peak antigen-binding activity and disease expression which may reflect either an effector or regulatory role for humoral immunity in recurrent EAE. Patterns of early antibody reactivity also distinguished F1 mice that developed or failed to develop disease signs after immunization, the latter exhibiting a consistent drop in antigen-binding activity 4 to 5 days before the usual onset of acute-stage paralysis. The results are considered with regard to possible mechanisms of chronic disease regulation in an environment of functional T cell suppression.

A double determinant sandwich immunoassay for quantitation of serum monoclonal anti-I-A antibody

A double-determinant sandwich radioimmunoassay (RIA) is described for the specific detection of anti-I-Ak monoclonal antibody (mAb) in the sera of non-Ighb murine hosts undergoing anti-Ia immunotherapy. This RIA utilizes 2 previously undescribed mAb reagents generated against an Ia.17-specific mAb secreted by the 10-3.6 hybridoma. The first reagent, 7.34, is specific for Ighb-linked allotypic determinants on the Fc portion of IgG2a immunoglobulins as defined by the pattern of reactivity with normal sera from a panel of inbred and Igh recombinant inbred strains. The second reagent, 58.3, is an anti-idiotypic mAb recognizing unique determinants in the combining site of 10-3.6 immunoglobulins, as determined by the specificity of the 58.3 mAb in solid-phase RIA and the capacity of this reagent to inhibit the binding of labeled 10-3.6 mAb to I-Ak-expressing spleen cells. In an RIA procedure using purified 58.3 mAb as substrate and 125I-labeled 7.34 as the detection reagent, serum concentrations of 10-3.6 as low as 1-5 ng/ml can be measured reproducibly after mathematical linearization of the sigmoid standard curve. In the present studies, the serum half-life of 10-3.6 mAb was calculated from assay data to be 3-5 h in I-Ak homo- or heterozygotes and 72 h in non-I-Ak mice. The serum level of 10-3.6 as a function of the mAb treatment protocol was also examined and results are considered with respect to the efficacy of different therapeutic regimens in prolonging transplant survival. Sandwich immunoassays of this type (RIA or ELISA) should provide a highly sensitive and specific means for monitoring serum mAb levels in individuals subjected to antibody immunotherapy for treatment of autoimmune disease, transplant rejection or tumor progression.

Regulation of transplantation immunity in vivo by monoclonal antibodies recognizing host class II restriction elements. II. Effects of anti-Ia immunotherapy on host T cell responses to graft alloantigens

Results of the preceding report demonstrated that in vivo treatment with monoclonal anti-I-A antibodies provided an effective means of prolonging the survival of murine tail skin allografts. The mechanism of antibody action was shown to include the activation of alloantigen-specific suppressor T cells (Ts), although the relationship between Ts expression and graft survival was not determined. This issue was addressed in the current studies through a kinetic analysis of suppressor and effector T cell responses in control and treated allograft recipients. Donor-specific delayed-type hypersensitivity (DTH) and cytotoxic T lymphocyte (CTL) responses were detectable in untreated A/J recipients of B10.A allografts 8 days after transplantation, rising to near maximum levels by day 12. Rejection in these animals occurred by day 11. In contrast, the predominant cellular response of anti-I-A treated animals for 12 days after transplantation was that of transferable suppression, DTH and CTL reactivity not being evident until day 15, coincident with the decay of Ts activity. Rejection in these animals was observed approximately 19 days post-transplant. CTL responsiveness in the latter group could not be reconstituted by the addition of antigen-presenting cells to the secondary in vitro culture system, nor was the CTL deficit due to antibody carry-over. It is considered that the altered expression of effector cell responses to graft alloantigens is due at least in part to the in vivo inhibition of helper T cell activity by anti-I-A-induced Ts, and that rejection in the treated host results from an eventual decline in the functional expression of this regulatory T cell subset.

Regulation of transplantation immunity in vivo by monoclonal antibodies recognizing host class II restriction elements. I. Genetics and specificity of anti-Ia immunotherapy in murine skin allograft recipients

Antibodies reactive with host class II restriction elements exert profound regulatory effects on the immune response to a variety of antigenic stimuli, including tumor, autoantigens, and alloantigens. In the present studies, monoclonal reagents specific for host I-A and I-E glycoproteins were evaluated for their capacity to modulate transplantation immunity in a murine tail skin allograft system. It was found that treatment of A/J mice with 200 micrograms 10-3.6 hybridoma-derived anti-I-Ak antibody daily for 10 days resulted in an average twofold increase in the survival time of B10.A minor antigen-incompatible allografts. Similar results were achieved by using class I, but not H-2-mismatched, donor tissue. Specificity of antibody activity was demonstrated by the failure of isotype-matched reagents recognizing irrelevant class II or relevant class I H-2 antigens to influence rejection under these conditions. Although antibodies reactive with graft as well as host alloantigens provided the greatest degree of prolongation, interaction with host restriction elements alone was sufficient for the in vivo expression of regulatory activity. As in previous studies, anti-I-A treatment was associated with the development of antigen-specific suppressor T cells that serve to dampen allograft immunity without altering secondary responses to unrelated antigens encountered after the initial treatment interval. These data suggest that anti-Ia immunotherapy may provide a clinically relevant approach toward the specific regulation of transplantation immunity in the appropriate donor-recipient combinations.

Regulation of transplantation immunity in vivo by monoclonal antibodies recognizing host class II restriction elements. I. Genetics and specificity of anti-Ia immunotherapy in murine skin allograft recipients

Antibodies reactive with host class II restriction elements exert profound regulatory effects on the immune response to a variety of antigenic stimuli, including tumor, autoantigens, and alloantigens. In the present studies, monoclonal reagents specific for host I-A and I-E glycoproteins were evaluated for their capacity to modulate transplantation immunity in a murine tail skin allograft system. It was found that treatment of A/J mice with 200 micrograms 10-3.6 hybridoma-derived anti-I-Ak antibody daily for 10 days resulted in an average twofold increase in the survival time of B10.A minor antigen-incompatible allografts. Similar results were achieved by using class I, but not H-2-mismatched, donor tissue. Specificity of antibody activity was demonstrated by the failure of isotype-matched reagents recognizing irrelevant class II or relevant class I H-2 antigens to influence rejection under these conditions. Although antibodies reactive with graft as well as host alloantigens provided the greatest degree of prolongation, interaction with host restriction elements alone was sufficient for the in vivo expression of regulatory activity. As in previous studies, anti-I-A treatment was associated with the development of antigen-specific suppressor T cells that serve to dampen allograft immunity without altering secondary responses to unrelated antigens encountered after the initial treatment interval. These data suggest that anti-Ia immunotherapy may provide a clinically relevant approach toward the specific regulation of transplantation immunity in the appropriate donor-recipient combinations.

Regulation of transplantation immunity in vivo by monoclonal antibodies recognizing host class II restriction elements. II. Effects of anti-Ia immunotherapy on host T cell responses to graft alloantigens

Results of the preceding report demonstrated that in vivo treatment with monoclonal anti-I-A antibodies provided an effective means of prolonging the survival of murine tail skin allografts. The mechanism of antibody action was shown to include the activation of alloantigen-specific suppressor T cells (Ts), although the relationship between Ts expression and graft survival was not determined. This issue was addressed in the current studies through a kinetic analysis of suppressor and effector T cell responses in control and treated allograft recipients. Donor-specific delayed-type hypersensitivity (DTH) and cytotoxic T lymphocyte (CTL) responses were detectable in untreated A/J recipients of B10.A allografts 8 days after transplantation, rising to near maximum levels by day 12. Rejection in these animals occurred by day 11. In contrast, the predominant cellular response of anti-I-A treated animals for 12 days after transplantation was that of transferable suppression, DTH and CTL reactivity not being evident until day 15, coincident with the decay of Ts activity. Rejection in these animals was observed approximately 19 days post-transplant. CTL responsiveness in the latter group could not be reconstituted by the addition of antigen-presenting cells to the secondary in vitro culture system, nor was the CTL deficit due to antibody carry-over. It is considered that the altered expression of effector cell responses to graft alloantigens is due at least in part to the in vivo inhibition of helper T cell activity by anti-I-A-induced Ts, and that rejection in the treated host results from an eventual decline in the functional expression of this regulatory T cell subset.

Monoclonal antibodies to tissue-specific cell surface antigens. I. Characterization of an antibody to a prostate tissue antigen

Monoclonal antibodies were raised to PC-3 human prostate adenocarcinoma cells, and one hybridoma, designated F77-129, was extensively purified and used to characterize a PC-3 antigen. The F77-129 antibody also showed serological reactivity with the Du-145 prostate cancer line and with three of four breast carcinoma lines tested; it showed variable binding to a colon carcinoma line. Several other lines tested, including melanomas, fibrosarcomas, and leukemias, were completely negative. Immunoperoxidase staining of frozen surgical specimens showed binding to both normal and malignant prostate and breast tissue. Injection of radioiodinated F77-129 into tumor-bearing nude mice showed specific in vivo targeting to prostatic cancer implants. The antigen also showed surface modulation by bound antibody, suggesting possible clinical utility of this antibody in delivering immunotoxins to tumors.

Regulation of the immune response to tumor antigens. X. Activation of third-order suppressor T cells that abrogate anti-tumor immune responses

The experiments described further define the suppressor T cell pathway in the S1509a tumor system. We demonstrated previously that S1509a-induced Ts1, TsF1, and Ts2 specifically suppress in vivo Ly1+2- T cell-dependent responses to S1509a and that Ts1 suppress in vivo Ly-1+2- T cell-mediated proliferative responses to S1509a. We have now shown that in vivo administration of either S1509a-induced TsF1 or TsF2 suppresses both in vivo and in vitro Ly-1+2- T cell-mediated responses to S1509a. Furthermore, we revealed the existence of Ts3, which are activated by S1509a tumor antigen and TsF2, in this murine tumor system. Finally, we demonstrated that cyclophosphamide abrogates the suppressive effect of TsF2 but not that of Ts3. These results are discussed with respect to T cell-mediated suppression in other murine tumor systems and the possible pivotal role for a tumor antigen-presenting cell in activating Ts3 in the S1509a tumor system.

Regulation of the immune response to tumor antigens. X. Activation of third-order suppressor T cells that abrogate anti-tumor immune responses

The experiments described further define the suppressor T cell pathway in the S1509a tumor system. We demonstrated previously that S1509a-induced Ts1, TsF1, and Ts2 specifically suppress in vivo Ly1+2- T cell-dependent responses to S1509a and that Ts1 suppress in vivo Ly-1+2- T cell-mediated proliferative responses to S1509a. We have now shown that in vivo administration of either S1509a-induced TsF1 or TsF2 suppresses both in vivo and in vitro Ly-1+2- T cell-mediated responses to S1509a. Furthermore, we revealed the existence of Ts3, which are activated by S1509a tumor antigen and TsF2, in this murine tumor system. Finally, we demonstrated that cyclophosphamide abrogates the suppressive effect of TsF2 but not that of Ts3. These results are discussed with respect to T cell-mediated suppression in other murine tumor systems and the possible pivotal role for a tumor antigen-presenting cell in activating Ts3 in the S1509a tumor system.

Suppressor T cell recognition of major and minor histocompatibility alloantigens: selected suppression of MHC-directed responses by minor alloantigen Ts

The induction of suppression by i.v. administered alloantigens in the murine host was analyzed as a model of the possible effects of blood transfusion on transplant survival. The results indicated that suppressor T cells (Ts) specific for minor histocompatibility alloantigens could be readily induced by the i.v. presentation of minor alloantigen-disparate spleen cells. In contrast, similar priming with cells differing solely at the H-2 major histocompatibility complex stimulated only positive T cell immunity, with no evidence of suppression. The induction of H-2 directed Ts activity could be accomplished only by i.v. priming with major plus minor incompatible donor cells, suggesting that suppressor cell recognition of minor alloantigens may have facilitated the generation of Ts against H-2-encoded major transplantation antigens. A role for minor histocompatibility antigens in the regulation of H-2-specific immunity at the effector level was also indicated. Ts induced by i.v. pretreatment with minor antigen-disparate donor cells not only suppressed the delayed-type hypersensitivity (DTH) response to the relevant minor alloantigens, but also inhibited DTH against unrelated H-2 alloantigens introduced during subsequent intradermal immunization. Suppression of H-2-directed T cell reactivity was specific in that the presence of the Ts-inducing minor alloantigens was also required and occurred only when the minor and unrelated major alloantigens were presented within the same inoculum, if not on the same cell surface. The capacity of Lyt-2+Ts or Ts-derived suppressive factors specific for one set of cell surface molecules to modulate responses to an unrelated group of surface antigens does not appear to represent a general phenomenon, because similar suppression of immunity to unrelated tumor-specific transplantation antigens by minor-specific Ts was not observed. These results are discussed with respect to the possible mechanism of H-2-directed suppression and the role of the I region in Ts recognition of antigen.

Suppressor T cell recognition of major and minor histocompatibility alloantigens: selected suppression of MHC-directed responses by minor alloantigen Ts

The induction of suppression by i.v. administered alloantigens in the murine host was analyzed as a model of the possible effects of blood transfusion on transplant survival. The results indicated that suppressor T cells (Ts) specific for minor histocompatibility alloantigens could be readily induced by the i.v. presentation of minor alloantigen-disparate spleen cells. In contrast, similar priming with cells differing solely at the H-2 major histocompatibility complex stimulated only positive T cell immunity, with no evidence of suppression. The induction of H-2 directed Ts activity could be accomplished only by i.v. priming with major plus minor incompatible donor cells, suggesting that suppressor cell recognition of minor alloantigens may have facilitated the generation of Ts against H-2-encoded major transplantation antigens. A role for minor histocompatibility antigens in the regulation of H-2-specific immunity at the effector level was also indicated. Ts induced by i.v. pretreatment with minor antigen-disparate donor cells not only suppressed the delayed-type hypersensitivity (DTH) response to the relevant minor alloantigens, but also inhibited DTH against unrelated H-2 alloantigens introduced during subsequent intradermal immunization. Suppression of H-2-directed T cell reactivity was specific in that the presence of the Ts-inducing minor alloantigens was also required and occurred only when the minor and unrelated major alloantigens were presented within the same inoculum, if not on the same cell surface. The capacity of Lyt-2+Ts or Ts-derived suppressive factors specific for one set of cell surface molecules to modulate responses to an unrelated group of surface antigens does not appear to represent a general phenomenon, because similar suppression of immunity to unrelated tumor-specific transplantation antigens by minor-specific Ts was not observed. These results are discussed with respect to the possible mechanism of H-2-directed suppression and the role of the I region in Ts recognition of antigen.

Cell receptors for the mammalian reovirus. I. Syngeneic monoclonal anti-idiotypic antibody identifies a cell surface receptor for reovirus

We have prepared and characterized a syngeneic monoclonal anti-idiotype directed against the idiotype (Id3) of the anti-reovirus type 3 hemagglutinin B cell hybridoma 9BG5. We have shown this monoclonal antibody to be anti-idiotypic in a series of inhibition studies with purified sigma 1 (hemagglutinin) protein and with absorption studies on the idiotypic R1.1 cell line. That the idiotype Id 3 defined by the monoclonal anti-idiotype is distinct from H-2 was demonstrated by its presence on an idiotype-expressing H-2 negative cell line (R1.E). Binding of the anti-idiotype is relatively tunicamycin resistant and pronase/trypsin sensitive, which suggests that the recognition site of the anti-idiotypic receptor is poorly glycosylated. The presence of idiotype-like receptors on reovirus type 3 susceptible neurons may have important implications for the presence of related gene families between neural and lymphoid tissue. The implications of recognition by neuronal cells of an anti-idiotypic monoclonal antibody directed against the reovirus 3 attachment receptor for the pathogenesis of viral-induced auto-immunity are discussed.

Cell receptors for the mammalian reovirus. I. Syngeneic monoclonal anti-idiotypic antibody identifies a cell surface receptor for reovirus

We have prepared and characterized a syngeneic monoclonal anti-idiotype directed against the idiotype (Id3) of the anti-reovirus type 3 hemagglutinin B cell hybridoma 9BG5. We have shown this monoclonal antibody to be anti-idiotypic in a series of inhibition studies with purified sigma 1 (hemagglutinin) protein and with absorption studies on the idiotypic R1.1 cell line. That the idiotype Id 3 defined by the monoclonal anti-idiotype is distinct from H-2 was demonstrated by its presence on an idiotype-expressing H-2 negative cell line (R1.E). Binding of the anti-idiotype is relatively tunicamycin resistant and pronase/trypsin sensitive, which suggests that the recognition site of the anti-idiotypic receptor is poorly glycosylated. The presence of idiotype-like receptors on reovirus type 3 susceptible neurons may have important implications for the presence of related gene families between neural and lymphoid tissue. The implications of recognition by neuronal cells of an anti-idiotypic monoclonal antibody directed against the reovirus 3 attachment receptor for the pathogenesis of viral-induced auto-immunity are discussed.

Regulation of the immune response to tumor antigens. IX. In vitro Lyt-1+2- cell proliferative responses to cellbound or subcellular tumor antigen

We investigated the cellular basis of immune reactivity to the S1509a fibrosarcoma in tumor-immune A/J mice. In a Winn assay, immune Lyt-1+2- T cells are capable of retarding S1509a tumor growth in naive A/J mice. In vitro proliferation to S1509a is also mediated by tumor-immune Lyt-1+2- T cells. This response is specific to the immunizing tumor and appears 5 to 7 days after reexposure to the tumor in vivo. Proliferation also requires the presence of a population of adherent cells. In fact, adherent peritoneal exudate cells pulsed with tumor membrane fragments derived from S1509a cells can stimulate proliferation. Proliferation is blocked by the addition of anti-I-Ak monoclonal antibody to the culture medium without complement or by treatment of the responder population with anti-I-Ak and complement. In vitro responsiveness is also inhibited by the presence of tumor-specific suppressor T cells in vivo. These observations suggest in vitro proliferation may provide a potential means of defining tumor antigens and cell-surface structures involved in tumor immunity.

Regulation of the immune response to tumor antigens. IX. In vitro Lyt-1+2- cell proliferative responses to cellbound or subcellular tumor antigen

We investigated the cellular basis of immune reactivity to the S1509a fibrosarcoma in tumor-immune A/J mice. In a Winn assay, immune Lyt-1+2- T cells are capable of retarding S1509a tumor growth in naive A/J mice. In vitro proliferation to S1509a is also mediated by tumor-immune Lyt-1+2- T cells. This response is specific to the immunizing tumor and appears 5 to 7 days after reexposure to the tumor in vivo. Proliferation also requires the presence of a population of adherent cells. In fact, adherent peritoneal exudate cells pulsed with tumor membrane fragments derived from S1509a cells can stimulate proliferation. Proliferation is blocked by the addition of anti-I-Ak monoclonal antibody to the culture medium without complement or by treatment of the responder population with anti-I-Ak and complement. In vitro responsiveness is also inhibited by the presence of tumor-specific suppressor T cells in vivo. These observations suggest in vitro proliferation may provide a potential means of defining tumor antigens and cell-surface structures involved in tumor immunity.

A behavioral approach to enuresis for the family physician

Enuresis is a chronic and prevalent disorder associated with childhood. Although nocturnal enuresis can be successfully hidden from outsiders, it is nevertheless annoying and destructive to family relationships. Behavior modification procedures have been most effective and efficient for treating enuresis. Three behavior modification approaches are presented with application suggestions for enuretic types elicited from interview data.

Conversion of immunity to suppression by in vivo administration of I-A subregion-specific antibodies

The in vivo administration of antibodies specific for gene products of the I-A subregion represents an immunologically specific approach to the manipulation of Ly-1+ T cell responses to antigen. This has been demonstrated previously by the capacity of anti-I-A antibody treatment to abrogate T cell-mediated delayed-type hypersensitivity (DTH) responses to syngeneic tumor antigen, hapten, and non-H-2 histocompatibility antigens. Evidence obtained in these studies suggested that the primary action of antibody was related to its ability to interfere with macrophage-T cell interactions during antigen presentation, consistent with the demonstration that similar antibodies inhibit T cell binding to antigen-pulsed macrophages in vitro. Results presented in this report provide evidence for an additional consequence of in vivo antibody administration that may be secondary to any direct effects on I-A-restricted antigen presentation. Thus, animals treated with I-A subregion-specific antibodies also develop a population of antigen-specific suppressor T cells (Ts) capable of inhibiting recipient Ly-1+ T cell responses to tumor antigen. The induction of suppression appeared to be an essential component of the total biological activity of these antibodies, because elimination of Ts precursors by cyclophosphamide also abrogated the antibody-mediated inhibition of DTH responsiveness. These results are discussed with respect to the possible mechanisms of Ts activation by anti-I-A antibody administration, and the general applicability of this approach as a means of clinical immunotherapy to limit inappropriate T cell responses in human disease.

Specific thymus-derived (T) cell recognition of papova virus-transformed cells

As a first step toward identifying papova virus-specific transplantation antigens and characterizing the immune response to these antigens, a series of congenic B10 mouse lines transformed by polyoma virus and SV40 has been obtained. B10.D2 (H-2d) mice immunized with x-irradiated polyoma-transformed B10.D2 cells (PyB10.D2) contained within their spleens a population of T cells that upon restimulation in vitro preferentially lyse 51Cr-labeled PyB10.D2 compared with other allogeneic polyoma-transformed target cells or SV40-transformed B10.D2 cells. Twenty hours after acute infection with polyoma virus, SV10.D2 cells express cell surface structures recognizable by polyoma-specific CTL. This CTL activity is therefore both polyoma specific and H-2 restricted, indicating associative recognition of H-2 molecules along with the virus-specific antigen.

Specific thymus-derived (T) cell recognition of papova virus-transformed cells

As a first step toward identifying papova virus-specific transplantation antigens and characterizing the immune response to these antigens, a series of congenic B10 mouse lines transformed by polyoma virus and SV40 has been obtained. B10.D2 (H-2d) mice immunized with x-irradiated polyoma-transformed B10.D2 cells (PyB10.D2) contained within their spleens a population of T cells that upon restimulation in vitro preferentially lyse 51Cr-labeled PyB10.D2 compared with other allogeneic polyoma-transformed target cells or SV40-transformed B10.D2 cells. Twenty hours after acute infection with polyoma virus, SV10.D2 cells express cell surface structures recognizable by polyoma-specific CTL. This CTL activity is therefore both polyoma specific and H-2 restricted, indicating associative recognition of H-2 molecules along with the virus-specific antigen.

T cell subset interactions in the regulation of syngeneic tumor immunity

Suppressor T cell (Ts) regulation of immunity to chemically induced syngeneic tumors has been investigated with regard to the mechanism of Ts stimulation and cell-to-cell communication. It has been determined that suppressor cells generated by the presence of tumor antigen participate in a suppressive circuit involving both cells and cell-derived factor(s) in the expression of suppressive effects. Evidence is provided that these interactions occur via idiotype--antiidiotype recognition in a manner similar to those in hapten-specific immune response. Conditions for induction of Ts activity in vivo have been artificially created by a variety of means, including the intravenous administration of soluble antigen and the inhibition of antigen-presenting function by anti-I-A antibodies or by in vivo treatment with ultraviolet irradiation. Suppression appears to be directed against the Ly-1+ cell, which mediates tumor immunity in this system. The summary of evidence suggest that responses to tumor antigen are in many aspects analogous to those occurring in response to more conventional antigens, but are subject to the dampening effects of suppressor cells generated continually during the period of primary tumor growth.

The role of T cell sets in the rejection of a methylcholanthrene-induced sarcoma (S1509a) in syngeneic mice

The ability of different T cell sets to confer protection in mice against a methylcholanthrene-induced sarcoma, S1509a, was examined. Intravenous infusion of lymph node and spleen cells from A/J donors immunized with S1509a into normal A/J recipients retarded subcutaneous growth of S1509a but did not lead to complete eradication of the tumor during a 9-day period of observation. This protective effect was lost if the transferred cells were treated with anti-Thy 1.2 and complement. The ability of different populations of lymphoid cells to retard tumor growth after inoculation with tumor cells subcutaneously was examined (Winn assay). Nylon-wool-passed cells from lymph nodes and spleens of tumor immunized animals were treated either with anti-Ly 1.2 or with anti-Ly 2.2 antiserums and complement and inoculated with tumor cells in normal A/J mice. The tumor was measured daily for 10 or more days. Ly l cells and unfractionated T cells efficiently suppressed tumor growth; Ly 23 cells had little or no effect. When small numbers of Ly 1 cells were injected along with twice as many Ly 23 cells, the growth of the tumor was also inhibited. Histologic examination of inoculated sites at 24-72 hours after local transfer showed a more intense mononuclear infiltrate in animals inoculated with tumor cells and T cells from immunized animals than in animals given injection with tumor cells alone, or with tumor cells and T cells from nonimmunized animals. The findings indicate that Ly 1 cells are capable of retarding the growth of the sarcoma, presumably by eliciting a delayed hypersensitivity reaction. By contrast, Ly 23 cells, which can mediate cytotoxicity, had little or no effect on tumor growth.