Mechanisms of suppressed cell-mediated immunity and impaired antigen-induced interleukin 2 production in granuloma-bearing mice

Pulmonary granulomas were induced in BALB/c mice immunized with methylated bovine serum albumin in complete Freund's adjuvant by the intratracheal injection of plain agarose beads or beads conjugated to specific antigen. Large hypersensitivity granulomas developed around antigen-coupled beads in immunized animals. Smaller but still prominent granulomatous reactions developed around plain beads in immunized mice. In nonimmunized animals, both plain and antigen conjugated beads produced very small granulomas. Granuloma formation in sensitized animals was associated with suppressed delayed-type hypersensitivity reactions induced by the footpad injection of specific and nonspecific antigens. Lymph node cells from sensitized granuloma-bearing mice with cutaneous anergy showed suppressed specific and nonspecific antigen-induced proliferative responses in vitro. These cells also showed suppressed interleukin 2 production in response to specific antigen. Although no soluble suppressive factor was detected in granuloma extracts, suppressor cells were found in lymph nodes of granuloma-bearing mice, which could inhibit antigen-induced production of interleukin 2 by lymph node cells from immunized mice. Antigen-specific immunoglobulin G antibody production was not suppressed in immunized granuloma-bearing mice. Previous studies from our laboratory have demonstrated migration inhibition factor and interleukin 1 activities in aqueous extracts prepared from granuloma-bearing lungs of immunized mice. These results and the findings reported here indicate that granuloma formation and the associated anergy observed in this system are primarily expressions of cell-mediated immunity; selective suppression of in vivo and in vitro expressions of cell-mediated immunity in granuloma-bearing mice may be due to impaired antigen-induced interleukin 2 production; and such impairment is caused by suppressor cells.     

Immunochemical characteristics of a factor causing antigen-specific lysis of thymus-dependent lymphocytes]

A factor capable of lysing in vitro, in the presence of a specific antigen, the cells of the lymph nodes and the thymus of intact mice was revealed in the supernatant obtained after the centrifugation of a suspension of viable cells of the lymph nodes and the thymus of the immunized mice. It was found by immunochemical methods that this factor had a mol. wt. of about 30000 dalton and an electrophoretic mobility in polyacrylamide gel exceeding that of mouse blood serum albumin. Besides, it was revealed by the precipitation reaction in agar that it was not an immunoglobulin or its chains.     

In vitro immune blastogenesis during contact sensitivity in tumor-bearing mice: I. Description of progressive impairment and demonstration of splenic suppressor cells

T-cell responsiveness was measured by the DNA response of disassociated spleen and lymph node cells when exposed to antigen in vitro. Sensitized splenic lymphocytes from fibrosarcoma-bearing mice immunized with 2,4-dinitro-1,5-difluorobenzene (DN2FB) demonstrated a progressive decrease in T-cell responsiveness to the haptenprotein conjugate DNP-BSA. Hyporesponsiveness to the dinitrophenylated-protein conjugate appeared in the spleens but not lymph nodes of tumorous animals. Normal host lymph node cells (LNC) responded strongly 24 to 48 h after sensitization and subsequently declined with a corresponding increase in responsiveness in the spleen. Tumor-bearing hosts (TBH) had similar LNC kinetics during immunization, however, spleen cells were significantly suppressed when compared to normal BALB/c mice sensitization kinetics. Spleen cells from TBH were also capable of suppressing the in vitro response of normal primed lymphocytes to DNP-BSA when admixed. Results from these experiments suggest that in vitro measurement of contact sensitivity was affected by suppressor cells/products existing in the spleens but not lymph nodes of fibrosarcoma-bearing mice.     

Mechanisms of in vivo generation of cytotoxic activity against allograft: 1. Local differentiation of mature cytotoxic T lymphocytes in rejection of allogeneic lymphocytes

Although cytotoxic activity was not detected within the spleen and regional lymph nodes from mice immunized sc with allogeneic lymphocytes, such activity was detected consistently in glass-nonadherent and anti-θ-sensitive peritoneal exudate cells (PE cells) from Day 5 after immunization and reached a maximum by Day 7. Immunized spleen cells developed cytotoxic T lymphocytes (CTLs) earlier and more effectively than normal spleen cells when transferred ip into X-irradiated syngeneic normal mice together with immunizing antigen, while they did not become cytotoxic when transferred without antigen. These results suggest that spleen and lymph node cells which may have differentiated into some transitional state by in vivo immunization may differentiate into mature CTLs, following direct contact with antigen at the site of graft. CTLs generated there appear to be responsible for the rejection of allogeneic lymphocytes. Cytotoxicity of PE cells was also generated in X-irradiated mice and augmented cytotoxicity was generated by treatment with cyclophosphamide.     

Effect of tumor immunity on the distribution of labeled lymphoid cells in tumor-challenged mice

The distribution of ⁵¹Cr-labeled lymphoid cells from normal mice and mice immunized against a tumor were compared after intravenous inoculation of the labeled cells into normal syngeneic recipients. Spleen cell preparations from immune donors contained increased percentages of spleen and bone marrow-seeking cells, thus suggesting expansion of these cell populations when immunity to a tumor exists. Homing of labeled normal cells in tumor cell-injected normal animals was somewhat different from that seen in tumor cell-inoculated mice that were immunized against the tumor. In the latter case, accumulations of lymph node and spleen cells in recipient lymph nodes and bone marrow were consistently lower. In contrast, lymphoid cells from animals immunized against the tumor were found to accumulate in virtually the same percentages in lymphoid organs of normal and immune recipients. The behavior of lymphoid cell populations from thymus or bone marrow that consist mainly of precursor cells was unaffected by presence of malignancy and/or tumor immunity.     

Contact sensitivity to picryl chloride: the occurrence of B suppressor cells in the lymph nodes and spleen of immunized mice.

Mice were immunized for contact sensitivity and antibody production by painting the skin with picryl chloride. Lymph node and spleen cells taken 4 days later transferred contact sensitivity. However, cells taken at 7–8 days failed to transfer but were able to block the transfer by 4 day immune cells. These suppressor cells occurred in the regional lymph nodes, spleen and thymus. The suppressor activity of lymph node and spleen cells was due to B cells as shown by the effect of anti-θ serum and complement, nylon wool filtration and separation of EAC positive and negative cells by centrifugation on a discontinuous gradient. The transfer of fractions rich or poor in macrophages showed that the suppressor cell in the transferred population was not a macrophage. Separation using EAC rosettes suggested that B cells were responsible for the suppressor activity in the thymus.T cells isolated from the lymph nodes and spleen 7–8 days after immunization transferred contact sensitivity although the initial population was inactive. This indicates that passive transfer cells are present in the regional lymph nodes and spleen at later times after immunization but cannot be demonstrated because of the presence of suppressor B cells. However, no passive transfer cells were found in the thymus. The production of B suppressor cells required little or no T cell help and following immunization the spleens of reconstituted (B) mice were at least as active as control cells in causing suppression. There are several different suppressor cells which act in the picryl system and the B suppressor cells in immunized mice described here are distinct from the T suppressor cells in mice injected with picryl sulphonic acid.     

The kinetics of antigen-reactive cells during lymphocyte recruitment

Lymphocyte recruitment, the increased traffic of lymphocytes from blood to lymph which occurs within antigenically stimulated lymph nodes, was monitored in the efferent lymph of single lymph nodes in sheep after immunization with allogeneic lymphocytes or purified protein derivative. Specific antigen-reactive cells were assayed by their ability to proliferate in vitro in the presence of the priming antigen. During lymphocyte recruitment such cells were no longer detected in the efferent lymph draining either the immunized node or a nonstimulated node remote from the region of antigen administration. These results probably reflect the selective removal of specific lymphocytes from the recirculating pool. Alternatively, the findings could involve a state of specific unresponsiveness of the cells.     

The suppressor T cell induced by syngeneic splenic cell antigen down-regulates hapten-specific cytotoxic T cells by elaborating a factor inhibitory for IL2-dependent cell replication

An in vitro study has been made of the mechanism by which a suppressor T cell, that is induced in lymph nodes by a syngeneic splenic cell antigen, prevents generation of cytotoxic T cells specific for hapten-altered self antigens. When popliteal lymph node cells exposed in vivo to syngeneic splenic cells were immunized in vitro with heat-treated syngeneic TNP-coupled thymocytes and excess helper factors, the Ts remained inactive. In this condition the exposed popliteal lymph node cells routinely demonstrated approximately twice the CTL response developed by lymph node cells from normal mice. Nevertheless, when triggered in vitro by splenic antigen on either X-irradiated B or T cells, the exposed but not the normal lymph node cells exhibited reduced hapten-altered self-specific CTL responses. Furthermore, T cells within spleen cell-exposed popliteal lymph node cell populations when reexposed to splenic T cells made a factor that was found to be suppressive of CTL generation by normal lymph node cells in vitro. The nondialyzable T-cell suppressor factor (TsF) did not appear to act on lymph node precursor CTLs, nor on helper T cells but instead acted at the level of utilization of helper factors in the development of CTLs. In an examination of the effect of TsF on cellular replication, TsF was found to be nontoxic for CTLL-20, an IL-2-dependent T cell, and it did not hinder the uptake of IL-2 by receptor blockade of this cell. Nevertheless, the replication of CTLL-20 that is IL-2 driven was diminished in the presence of TsF. Similarly, TsF was found to be inhibitory for T-cell proliferation stimulated by mitogen but had no effect on a B myeloma cell proliferative response. Thus, TsF appears to act as an inhibitor of a T cell's capability to replicate despite the presence of the stimulus for replication, namely, IL-2.     

Effect of thymus cell injections on germinal center formation in lymphoid tissues of nude (thymusless) mice

Nude mice, partially backcrossed to Balb/c or DBA/2, were injected iv with 5 × 10⁷ thymus cells from the respective inbred strain. The response of these mice to immunization with Brucella abortus antigen was studied, with respect to both antibody production and the formation of germinal centers in their lymphoid tissues. The results were compared to those obtained with nude mice to which no thymus cells were given, as well as to Balb/c, DBA/2, or +/? litter mate controls.Nude mice formed less 19S as well as 7S antibody than did litter mate controls and completely lacked germinal centers in lymph nodes and gut-associated lymphoid tissue. Those nude mice which had been injected with thymus cells made a much better secondary response, both for 19S and for 7S antibody, and had active germinal centers in their lymph nodes as early as 3 wk after thymus cell injection. Intestinal lymphoid tissue in nude mice showed only slight reconstitution of germinal center activity several months after thymus cell injection and none at earlier times. Irradiated (3000 R) thymus cells appeared as effective as normal cells in facilitating germinal center appearance and 7S antibody production in the nude mice.     

In Vitro Studies on the Mechanism of Acquired Resistance to Tuberculous Infection

Immune lymph node cells were obtained from mice immunized with bovine gamma globulin (BGG) in complete Freund's adjuvant or allogeneic MH134 tumor cells. They showed the capacity of conferring bactericidal activity on macrophages infected with Mycobacterium tuberculosis, H37Rv, when they were incubated on macrophage monolayers together with the corresponding antigen, i.e., BGG or solubilized cellular antigen of the tumor cells. However, such capacity was lower than that of tubercle bacilli-immune lymph node cells. Culture supernatants were harvested after incubation of tubercle bacilli-immune, BGG-immune or allogeneic tumor-immune lymph node cells with the corresponding antigen for 24 hr. Macrophages were altered so as to suppress intracellular bacillary growth when macrophage monolayers were exposed to the supernatants for more than 2 days. When normal lymph node cells were incubated on normal macrophage monolayers together with a mitogen such as PHA or concanavalin A, growth of tubercle bacilli within the macrophages was slightly but difinitely suppressed. The mechanism of elicitation of cellular immunity to the infection with tubercle bacilli is discussed on the basis of results presented in this and the preceding paper.     

Murine delayed hypersensitivity (DHS): modulation of in vitro antigen-induced responsiveness of lymph node cells from mice expressing DHS to human gamma-globulin by lymphocyte populations from normal syngeneic animals

Using a chemically defined, protein-free medium, the modulatory effect of normal (N) lymphocytes on in vitro antigen-induced proliferation by lymph node cells (LNC) from mice immunized to express delayed hypersensitivity (DHS) to human γ-glogulin (HGG) was quantitated in coculture. LNC from normal syngeneic animals exerted little if any effect on immune-LNC proliferation. Compared with immune-LNC plus N-LNC coculture response. N thymus cells (TC) were consistently suppressive while N spleen cells (SC) varied in their effect from a marginal to a marked potentiation of radiolabeled thymidine incorporation. Inactivation of N-SC suspensions by X irradiation prior to coculture with immune LNC abrogated the increased responsiveness. It therefore appeared that interaction of immune LNC and antigen resulted in recruitment of N-SC to proliferate. Separation of N-SC suspensions to provide enriched populations of thymic-independent (B) and thymic-dependent (T) lymphocytes showed that B cells augmented and T cells suppressed HGG-induced incorporation of [3H] thymidine when cocultured with immune LNC.     

Specific immunosuppression by passive antibody. V. Participation of macrophages in reversal of suppression by peritoneal exudate cells from immune animals

Thioglycollate-stimulated peritoneal exudate cells (PEC), harvested from mice immunized against sheep erythrocytes (SRBC) and transferred to normal syngeneic recipients, reverse the immunosuppression caused by passively administered anti-SRBC antibody. Macrophages purified from PEC on BSA gradients did not reverse immunosuppression; neither did suspensions of cells from mesenteric lymph nodes of immune mice. Mixtures of the purified macrophages and lymph node cells were fully capable of reversing immunosuppression. Thus, two types of cell, one a macrophage and one a lymphocyte, are required. Both must be compatible with the recipient mice at the H-2 complex. However, only the macrophages must necessarily be obtained from an immune donor. When “immune” macrophages were preincubated in vitro with “normal” lymph node cells before transfer to antibody-treated syngeneic recipients, a significant reversal of the immunosuppressive effect occurred. The ability of whole PEC or spleen cells to reverse the immunosuppressive effect of passive antibody is acquired rapidly after injection of a single low dose of antigen. Development of this ability precedes the appearance, in the circulation, of immunosuppressive antibody.     

Cyclic kinetics and mathematical expression of the primary immune response to soluble antigen

The kinetics and the distribution of antigen and antibody were shown to be similar in four species of experimental animals and in two species of wild rodents immunized with the protein-polysaccharide capsular plague antigen. Serologically active antigen and antibody were detected in homologous conjugating serological tests. Soluble antigen persists at the injection site for as long as a week and adsorbed antigen for two weeks or more. Antigen persists in the blood of animals for 2–4 days. In regional popliteal lymph nodes, antigen was detected for the first days, followed by antibody in both lymph node and blood. Plasma cell response was more intensive in animals inoculated with adsorbed antigen. The gradual decrease of antigen at the injection site shows superimposed up-and-down changes, mostly parallel with the antibody in the popliteal lymph node and blood, as well as with plasma cell response in the regional lymph node. Serological cycles were related to the resistance of immunized white mice to plague infection. Cyclic kinetics of specific polysaccharide in the faeces of dysentery patients was found.     

Antigen-specific lysis in vitro of lymph node cells of intact mice injected with RNA from viable lymph node cells of immunized animals]

Supernatant fluid obtained after centrifugation of the suspension of viable lymph node cells of immunized animals proved to induce in vivo in the lymph node cells of intact mice sensitivity to lysis with a specific antigen in vitro. This property was possessed after chromatography of the supernatant fluid on Sephadex G-200 by the 3rd fraction (MW about 30000 dalton). DNA-ase, trypsin or deproteinization failed to influence whereas RNA-ase inactivated this fraction in respect to the inducing properties.     

Enhancement of macrophage bactericidal capacity by antigenically stimulated immune lymphocytes

The ability of antigenically stimulated immune lymphocytes to influence the bactericidal capacity of normal macrophages was studied in vitro. Purified lymphocytes were obtained from the lymph nodes and peritoneal exudates of guinea pigs immunized with bovine gamma globulin (BGG) and from control animals. Immune and control lymphocytes were added to normal macrophages and incubated overnight in the presence or absence of BGG. After washing, the macrophage monolayers were infected with Listeria monocytogenes; 4 hr later, the cells were lysed and the surviving intracellular bacteria quantitated. The macrophages which had been incubated with BGG-immune lymphocytes in the presence of BGG displayed a markedly enhanced listericidal capacity. In parallel experiments, these same antigen-stimulated lymphocytes were shown to inhibit the migration of normal macrophages. Lymphocytes derived from peritoneal exudates were more active than lymph node lymphocytes in both assays.     

Failure of ovalbumin associated with allogeneic spleen ceels to stimulate proliferation of lymph node cells of immune mice.

Ovalbumin-pulsed spleen cells were found to stimulate thymidine uptake of lymph node cells of syngeneic mice immunized with ovalbumin in complete Freund's adjuvant after treatment of spleen cells with Mitomycin C but not after heating the spleen cells at 56degrees for 30 min. Ovalbumin-pulsed spleen cells of allogeneic mice failed to stimulate the immune lymph node cells more than unpulsed cells, although a net increase in the thymidine uptake above the allogeneic stimulation was observed when free ovalbumin was added to the mixed culture. To eliminate the high background of the mixed lymphocyte reaction, F1 mice were made chimeric with bone marrow of one of the parental strains. Using lymph node cells of the immunized chimeras, the stimulation by pulsed spleen cells was much greater when antigen was presented on cells of the parental strain used for bone marrow injection than when presented on cells of the other parental strain.     

Synergy among rat T cells in the proliferative response to alloantigen.

A synergistic interaction in the proliferative response to alloantigen is described for mixtures of rat thymus and lymph node cells. The optimal conditions for synergy are quantitatively defined. Regression analysis of the slope of the dose-response curve has been utilized to estimate the degree of interaction in thymus-lymph node cell mixtures. The slope of the response of cell mixtures was noted to be significantly greater than the slope for the response of lymph node cells alone. Irradiation was shown to have a differential effect on the response of thymus and lymph node cells in mixtures. Irradiated thymus cells retained the capacity for synergy in mixtures, whereas irradiated lymph node cells did not. Additional studies have demonstrated that both de novo protein synthesis and specific antigen recognition by both responding cell populations in mixtures was required for maximal synergy. These studies demonstrate that synergy cannot be explained as an artifact of altered cell density in vitro. They establish that thymus cells and lymph node cells represent distinct subsets which manifest qualitatively different functions in the proliferative response to alloantigen. Thymus cells can respond directly to alloantigen by proliferation but also have the capacity to amplify the proliferative response of lymph node cells—a capacity which is resistant to X irradiation but requires recognition of alloantigen and de novo protein synthesis. Lymph node cells may similarly respond by proliferation to alloantigen but lack the amplifier activity of thymus cells. Synergy for rat lymphoid cells, like mouse lymphoid cells, has been shown to involve an interaction of thymus-derived lymphocytes.     

In vitro studies on the mechanism of acquired resistance to tuberculous infection. II. The effects of the culture supernatants of specifically stimulated-sensitized lymphocytes on the growth of tubercle bacilli within macrophages.

Immune lymph node cells were obtained from mice immunized with bovine gamma globulin (BGG) in complete Freund's adjuvant or allogeneic MH134 tumor cells. They showed the capacity of conferring bactericidal activity on macrophages infected with Mycobacterium tuberculosis, H37Rv, when they were incubated on macrophage monolayers together with the corresponding antigen, i.e., BGG or solubilized cellular antigen of the tumor cells. However, such capacity was lower than that of tubercle bacilli-immune lymph node cells. Culture supernatants were harvested after incubation of tubercle bacilli-immune, BGG-immune or allogeneic tumor-immune lymph node cells with the corresponding antigen for 24 hr. Macrophages were altered so as to suppress intracellular bacillary growth when macrophage monolayers were exposed to the supernatants for more than 2 days. When normal lymph node cells were incubated on normal macrophage monolayers together with a mitogen such as PHA or concanavalin A, growth of tubercle bacilli within the macrophages was slightly but difinitely suppressed. The mechanism of elicitation of cellular immunity to the infection with tubercle bacilli is discussed on the basis of results presented in this and the preceding paper.     

Role of cyclic AMP on differentiation of T- and B-lymphocytes during the immune induction.

Spleen cell cultures from genetically thymus-deficient nude mice were restored with a T-cell replacing factor obtained from normal spleen cells of Balb/c-Ig^b mice stimulated with concanavalin A. Treatment of these cultures with an inhibitory dose of cyclic AMP did not result in reduction of the number of specific antibody-forming cells after stimulation by antigen, whereas the same treatment led to inhibition in cultures restored with normal hydrocortisone-resistant thymus lymphocytes. Further experiments lead to the conclusion that the early effect of cAMP on the immune induction seen in vitro reflects inhibition of the production or secretion of a T-cell factor which is a prerequisite for triggering B-cells with a thymus-dependent antigen.     

Studies on the mechanism of the enhancement of delayed-type hypersensitivity by pertussigen

The potentiation of delayed-type hypersensitivity (DTH) reactions by pertussigen, a protein toxin from Bordetella pertussis, has been studied in adoptive transfer assays. Lymph node or spleen cells from mice treated with or without pertussigen at the time of immunization with protein antigens were transferred to naive, syngeneic recipients that were challenged with antigen. Cells from donors treated with pertussigen had the capacity to transfer vigorous, antigen-specific DTH reactions. Cells from immunized donors not given pertussigen transferred little or no DTH. These results indicate that pertussigen is able to augment DTH reactions by potentiating the antigen reactivity of cell populations in lymphoid organs. The phenotype of the effector cells induced by pertussigen was Thy-1 positive, L3T4 positive, and Ly-2 negative. Cells from mice given pertussigen and an irrelevant antigen had no influence on specific DTH responses, suggesting that pertussigen enhances the activity of the antigen-specific cell type mediating DTH. The effect of pertussigen and of immunization on the lymphocyte subpopulations present in the lymph nodes was studied by analysis of suspensions of lymph node cells by flow cytometry. In immunized and in nonimmune mice, pertussigen increased the ratio of Ly-2-negative:Ly-2-positive T cells, and reduced the overall proportion of B cells. In immunized mice, pertussigen induced a much higher proportion of large dividing cells from 5 days after sensitization onwards. The relevance of these changes in lymphocyte behavior to the development of enhanced and prolonged DTH in mice given pertussigen is discussed.