Characterization of the accessory cells involved in suppressor T cell induction

The ability of UV-treated splenic adherent cells (SAC) to induce T cell-mediated immunity and suppressor T cells was analyzed in the 4-hydroxy-3-nitrophenyl acetyl (NP) system. UV irradiation of 0.88 KJ/m2 decreased the capacity of NP-coupled SAC to induce delayed-type hypersensitivity (DTH) responses by about 50%. The ability of uncoupled UV-treated SAC to induce allogeneic DTH response was also imparied, indicating that UV-treated SAC are inefficient at inducing DTH in these systems. TS1 induction by UV-treated NP-SAC was evaluated TS1 induction by UV-treated NP-SAC was evaluated by using adherent cells that were subjected to the same dose of UV irradiation that impaired DTH induction. Intravenous administration of 10(3) or 10(4) UV-treated NP-coupled SAC induced TS1 cells with the same efficiency as non-UV-irradiated cells. The TS1 cells induced in this fashion were antigen specific. Furthermore, to establish that the antigen was not reprocessed by the host, I-J-mismatched, UV-treated NP-SAC were unable to induce TS1 cells. The population of antigen-presenting cells responsible for TS1 induction appear to express both I-A and I-J determinants. TS2 induction by UV-treated accessory cells was also analyzed. TSF1 inducer suppressor factor was pulsed onto graded numbers of either normal or UV-treated adherent cells. The same levels of antigen-specific suppression were induced with normal and UV-treated cells. Finally, TS3 induction by UV-treated NP-SAC was analyzed. UV-treated and normal NP-SAC (3 X 10(3] induced antigen-specific suppression of NP DTH responses. I-J-mismatched, UV-treated NP-SAC failed to induce suppression, suggesting that the hapten was not reprocessed by the host under these experimental conditions. The accessory cell population responsible for TS3 induction appears to express both I-A and I-J determinants. Thus, there are at least two functional distinctions between the antigen-presenting cells that induce immunity vs those that induce suppressor cells. First, UV treatment selectively impairs the antigen-presenting cells, which activate the positive limb of the immune response. Second, I-J determinants appear to be specifically associated with the SAC, which induce suppressor T cells. Although these criteria can be used to distinguish the accessory cells involved in suppressor cell pathways from those controlling helper T cell induction, there were no discernible phenotypic differences among the accessory cells that induce the TS1, TS2, and TS3 subsets.     

A role for L3T4+ T cells and their lymphokines in the generation of suppressor effector (TS3) cells

The cellular requirements for the in vitro induction of antigen-specific suppressor T cells were examined. Previous reports indicated that Ia-bearing macrophages and anti-idiotypic B cells are required as accessory cells to facilitate the generation of suppressor effector (TS3) cells which regulate the response to the 4-hydroxy-3-nitrophenyl acetyl (NP) hapten. The present study describes two distinct T cell populations which interact to generate antigen-specific TS3. Fractionation of the T cell populations with monoclonal antibody to the L3T4 determinant led to the identification of an NP-specific L3T4- TS3 progenitor population and an L3T4+ helper/inducer subset. In the presence of NP-coupled antigen, the L3T4+ subset could induce progenitor TS3 to differentiate into mature TS3 cells. The activity of the L3T4+ inducer population could be replaced with specifically activated cloned helper cells which were not NP-reactive since an I-Ab-restricted, insulin-reactive, L3T4+ clone was capable of supporting the generation of NP-specific TS3. Inducer activity appeared to be confined to the Th1 but not the Th2 subset. In addition, 18-hr supernatants from antigen-activated clones were capable of substituting for L3T4+ cells or T cell clones in TS3 induction cultures. The TS maturation/differentiation factor(s) active in these supernatants does not appear to be IL-1, IL-2, IL-3, or interferon-gamma alone since purified sources of these lymphokines failed to induce TS3 activity.     

Involvement of antigen and I-J determinants in the induction of effector T suppressor cells by immune B cells

Immune B cells induce effector T suppressor cells in vitro. The B cells act as antigen-presenting cells, and express both I-A and I-J determinants. Antigen and I-J determinants are required for the induction of suppressor T cells by immune B cells, but I-A determinants are not. These findings indicate that precursors of suppressor T cells appear to recognize antigen in the context of I-J determinants on the surface of immune B cells.     

The role of adherent accessory cells in the generation of effector suppressor T cells

The role of accessory cell populations in the generation of effector suppressor (Ts3) cells was studied. By using an in vitro culture system, it was previously determined that the induction of NP-specific effector suppressor activity requires T cells, antigen, and an anti-idiotypic B cell population. We now demonstrate that the generation of Ts3 cells in this system also requires accessory cells. The accessory population appears to play a role in the processing and presentation of antigen. These antigen-presenting accessory cells are required early in the induction phase of Ts3 generation. These accessory cells can present NP coupled to immunogenic or non-immunogenic polypeptide carriers, including polymers of L-amino acids. However, NP coupled to polymers of poorly metabolized D-amino acids fail to induce suppressor T cell generation. Furthermore, the data demonstrate that an H-2 homology must exist between the Ts3 precursors and the antigen-presenting cell population if suppressor activity is to be generated. We also characterize the differential genetic restrictions that govern the induction of Ts3 cells that control suppression of either T cell or B cell responses. The data suggest that although I-J region encoded gene products control the induction and effector phases of suppressor cell activity as measured on T cell responses, the suppression of B cell responses appear to be controlled by I-A gene products. Possible cellular mechanisms that might explain these findings are discussed.     

Mechanism of action of a T suppressor factor (TsF) in contact sensitivity: the T cell target for TsF activity in adoptive transfer of immunity is not effector cell

The passive transfer of contact sensitivity (CS) by immune cells into normal animals requires the interaction of two distinct Ly-1+ T cells, one which is Vicia villosa lectin (VV)-nonadherent, the other which adheres to VV. Functional deletion of either cell type abrogates the adoptive transfer of CS into normal animals, whereas VV-nonadherent cells alone can transfer CS into animals pretreated with cyclophosphamide (Cy). An antigen-specific T suppressor factor, designated TNP-TsF, inhibits the transfer of CS into normal adoptive recipients. TNP-TsF mediates its suppressive activity by inducing an I-J+ subfactor (designated I-J2) from the assay population by the interaction of PC1-F (a TNP-binding subfactor of TNP-TsF) with antigen-primed Ly-2+ T cells. This I-J+ subfactor then complements TNBS-F (an antigen-nonbinding subfactor of TNP-TsF) to form an antigen-nonspecific effector molecule which suppresses DTH responses in an antigen-nonspecific fashion. We report here that TNP-TsF suppresses the adoptive transfer of CS into normal animals but not into animals pretreated with Cy. TNBS-F + I-J2, the effector complex of TNP-TsF, also suppresses the transfer of CS into normal but not Cy-treated animals. When the Ly-1 immune cells were separated into VV-adherent and -nonadherent populations, the TNBS-F + I-J2 suppressor complex suppressed the functional activity of the VV-adherent cell population, but not the VV-nonadherent cells. This suppressive activity correlates with the need for VV-adherent cells in the transfer of CS into normal but not Cy-treated recipients. When an I-J+ molecule (I-J1) from an SRBC-specific TsF was used in place of I-J2 to form a suppressor complex with TNBS-F, this TNBS-F + I-J1 TsF suppressed the transfer of CS into both normal and Cy-treated recipients. This difference in functional suppressive activity correlated with a difference in target cell specificity: TNBS-F + I-J1 suppressed the VV-nonadherent TDTH cell, whereas TNBS-F + I-J2 suppressed the VV-adherent T cell of CS. Immune cells which are transferred under conditions which do not require the VV-adherent cell for transfer are not suppressed by TNBS-F + I-J2 or TNP-TsF, but are suppressed by the TNBS-F + I-J1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regulation of granulomatous inflammation in murine schistosomiasis. III. Recruitment of antigen-specific I-J+ T suppressor cells of the granulomatous response by I-J+ soluble suppressor factor

Down-modulation of the schistosome egg-induced granulomatous response involves various interacting subsets of T suppressor (TS) lymphocytes. In the present study the inductive phase of the process of modulation was analyzed. A soluble, I-J+ granuloma TS cell recruiting factor (Gr-TSRF) derived from spleen cells of chronically infected mice is described. This factor eluted from immunoabsorbent columns coupled with anti-I-Jk alloantisera induced the recruitment and expansion of antigen-specific I-J+ TS cells from a TS precursor cell population in the spleens of acutely infected mice. The recruited TS cells suppressed the granulomatous response of normal recipients in a 2-day adoptive transfer model. The antigenic specificity of the recruited TS cells was demonstrated by their inability to suppress KLH-induced artificial granulomatous response. This mechanism of recruitment described in the current study and illustrated by adoptive transfer experiments is likely to be active in vivo in initiating the process of spontaneous modulation. The I-J+ Gr-TSRF and the I-J+ TS cell described in this paper, together with the previously described H-2 restricted I-C+ factor and the subsets of TS cells (THs, TSe, TSpr), indicate the existence of an intricate, regulatory pathway(s) that operates during the modulation of the granulomatous response.     

Modulation of suppressor T cell induction with gamma-interferon

The ability of antigen-coupled splenic adherent cells to induce suppressor T cells (Ts) is dependent on the presence of I-J determinants on antigen-presenting cells. After 4 days of in vitro culture, antigen-coupled adherent cells lose the capacity to induce Ts. Supernatants from Con A-stimulated lymphocyte cultures and purified interferon-gamma can sustain accessory function for the induction of Ts. Furthermore, after in vitro culture of splenic adherent cells, there is an apparent correlation between the loss of I-A determinants and the decrease in I-J-restricted Ts induction. Stimulation of Ia expression with interferon-gamma results in a simultaneous increase in the ability to induce Ts. Finally, elimination of I-A-bearing splenic adherent cells with antibody + C eliminates I-J-restricted Ts induction. The combined data imply a co-regulation of I-A and I-J on the antigen-presenting cells involved in the induction of both the Ts1 and Ts3 suppressor T cell subsets.     

Functional analysis of cloned macrophage hybridomas. VI. Differential ability to induce immunity or suppression

We previously screened a series of macrophage hybridomas derived from fusion of P388D1 (H-2d) tumor cells with CKB (H-2k) splenic adherent cells for their ability to induce I-J restricted Ts cell responses. One Ia+ macrophage clone (63) consistently induced Ag-specific, I-J-restricted Ts. To evaluate whether macrophage hybridoma 63 also induced delayed-type hypersensitivity (DTH) immunity, mice were immunized with hapten-coupled macrophage hybridoma cells. Hapten-coupled splenic adherent cells and control macrophage hybridomas induced significant primary DTH responses, whereas hapten-coupled macrophage 63 induced little or no immunity when injected into H-2 compatible hosts. However, macrophage hybridoma 63 specifically activated I-Ak, I-Ad, or I-Ed restricted T cell hybridomas/clones, in vitro in the presence of appropriate Ag. Three different strategies designed to eliminate suppressor cell activity were successfully used to demonstrate that hapten-coupled macrophage 63 could also induce in vivo immunity. First, after immunization with hapten-coupled macrophages, mice were treated with cyclophosphamide. Second, macrophage 63 was treated with anti-IJ idiotype antibody before 4-hydroxy-3-nitrophenyl acetyl hapten (NP) coupling. Finally, haptenated macrophages were injected into I-A compatible but I-J incompatible recipients. These protocols are known to inhibit the induction of Ts activity, thus these results indirectly suggest that there is stimultaneous generation of Ts activity in vivo. The latter hypothesis was tested in adoptive transfer experiments. Transfer of lymph node cells from NP-63 primed B10.BR (H-2k) mice induced immunity in naive 4R animals, whereas the same number of immune cells suppressed NP-induced DTH responses in 5R mice. The combined results indicate that a cloned macrophage line can activate both Th and Ts cells. Macrophages which induce Ts activity may be responsible for maintaining the balance of immunity vs suppression. The data support the hypothesis that IJ interacting molecules (IJ-IM) expressed on macrophages are critical for induction of suppressor cell activity.     

Alloreactive cloned T cell lines. VII. Comparison of the kinetics of IL 2 release stimulated by alloantigen or Con A

Injection of poly(Glu50Tyr50)(GT) into B10.BR (H-2k) mice induces GT-specific suppressor T cells and a T cell-derived suppressor factor (TsF1), which in turn induces a second-order suppressor T cell (TS2). In the present study, we show that B10.BR GT-TSF1 is composed of separate I-Jk and idiotype-bearing chains linked by disulfide bond(s). Functional suppressive activity requires both chains to be in association. Neither chain alone can induce TS2, indicating that both chains must be seen in association and suggesting a single cellular target for the two chains. Experiments designed to interchange I-J-bearing chains of GT-TSF1 derived from different H-2 haplotypes indicate that only the homologous I-J and idiotype-bearing chains can reassociate into a suppressive moiety. These experiments may imply heterogeneity of I-J region gene products.     

The immune response and the eye. II. The nature of T suppressor cell induction in anterior chamber-associated immune deviation (ACAID)

We studied the cellular basis for the induction of Ts cells in anterior chamber (AC)-associated immune deviation (ACAID) by using TNP-modified syngeneic spleen cells (TNP-Spl). We demonstrate that the cells responsible for the induction of TNP-ACAID are non adherent, IA- T cells. This is in contrast to the antigen-presenting cells which induce suppression after the i.v. injection of TNP-Spl which are IA+/I-J+ adherent cells. Furthermore, two T cells within the TNP-Spl population are required to initiate suppression in TNP-ACAID: one is Lyt-1+, and I-J+, the other is Lyt-1+ and reactive with a monoclonal antibody, 14-30, which specifically identifies Ts inducer cells. The antigen specificity of ACAID resides in the 14-30+ T cell, and not the I-J+ cell. Although both cells must be viable to induce suppression, neither they (nor their products) must be in direct contact within the eye; one population may be in the right AC, the other in the left. Our results suggest that it is Ts inducer cells placed into the AC of the eye which initiate TNP-ACAID, and that these cells exit (or secrete Ts factors which exit) the eye to induce Ts effector cells in the spleen.     

Infectious and noninfectious tolerance are blocked by a monoclonal antibody to T-suppressor factor

Two forms of hapten-specific unresponsiveness have been demonstrated following intravenous (iv) injection of hapten-conjugated syngeneic spleen cell based on the nature of the antigen-presenting cell (APC): I-J+, I-A- APC have been shown to induce T-suppressor cells (Ts cells) which are demonstrated upon adoptive transfer, while I-J-, I-A+ APC induce a nontransferable tolerance. In this paper we report that a monoclonal antibody specific for T-suppressor effector cells and factors (14-12) can block the Ts cells induced by I-J+, I-A- APCs and the tolerance induced by I-J-, I-A+ APCs. In addition, it sufficiently overcomes suppression such that injection of TNP-spl iv induces immunity rather than suppression. We show that the I-A+, I-J- TNP-spl, which induce nontransferable tolerance upon iv injection, are the cells which induce immunity in 14-12-treated recipients. These results demonstrate that injection of I-J-, I-A+ APC does not lead to clonal deletion and the tolerance induced by the iv injection of both I-J+, I-A- and I-J-, I-A+ APC operate via Ts cells.     

Suppression of IgG memory responses by T cells activated with the type 2 antigen polyvinylpyrrolidone (PVP)

Although type 2 antigens, such as polyvinylpyrrolidone (PVP), generally do not prime for IgG memory responses or activate specific helper T cells (TH), previous studies have established that low doses of PVP (0.0025 microgram) can prime for IgG memory and induce TH in vivo. Doses of PVP that are optimally immunogenic for IgM antibody production (0.25-25 micrograms) do not prime for IgG memory responses and preferentially activate PVP-specific suppressor T cells (TS) which suppress IgG antibody production. The studies reported here further characterize PVP-specific TS and begin to investigate the mode of action of these TS. TS induced with high doses of PVP have a typical suppressor cell surface phenotype in that they are Lyt 2+, I-J+, L3T4-, I-A- T cells. PVP-specific TS are inducible in mice expressing the X-linked immune defect and are Igh restricted in their actions. These TS suppress PVP-specific IgG responses of PVP-HRBC (horse red blood cells)-primed B cells when the TH population is from low-dose PVP-primed mice but not when the TH population is from PVP-HRBC-primed mice. Thus the TS do not apparently directly suppress the B-cell responses but act indirectly to suppress IgG responses by preventing the expression of PVP-specific TH function. The TS induced by 0.25 microgram PVP also prevent the generation of PVP-specific memory B cells apparently by preventing the expression of functional TH which are required for induction of memory B cells. Elimination of TS activation by pretreatment of mice with cyclophosphamide at the time of priming with 0.25 microgram PVP results in the expression of TH function and priming of memory B cells.     

Hapten-specific T cell responses to 4-hydroxy-3-nitrophenyl acetyl. XIII. Characterization of a third T cell population involved in suppression of in vitro PFC responses

The involvement of a third-order suppressor T cell population (Ts3) in the suppression of in vitro PFC responses was analyzed. It was shown that Ts2 effector-phase suppressor cells, induced by the i.v. injection of NP-coupled syngeneic spleen cells, require a third suppressor T cell population to effect NPb idiotype-specific suppression of an in vitro B cell response. This Ts3 population was shown to be present in NP-primed but not unprimed donors. The Ts3 population specifically binds NP and is Lyt-1-, Lyt-2+, I-J+ and bears NPb idiotypic determinants. The involvement of the Ts3 population in a suppressor pathway that requires recognition of idiotypic determinants is discussed.     

The delayed-type hypersensitivity response to (4-hydroxy-3-nitrophenyl) acetyl- (NP) coupled proteins is carrier-specific: in vivo and in vitro demonstrations

In vivo and in vitro approaches for measuring DTH to NP and the cross-reactive hapten, NIP, were taken. Mice were immunized subcutaneously with NP-OVA, NP-BGG or NP-CGG in CFA or NP-spleen cells, challenged intradermally with NP or NIP-coupled to a heterologous carrier, and footpad or ear swelling determined 4, 24, and 48 h later. Alternatively, draining LNC were removed and challenged in vitro with either haptenated protein or haptenated, irradiated, syngeneic spleen cells to induce lymphotoxin (LT) production or proliferation. Our results show that although carrier-specific DTH responses are easily elicited both in vivo and in vitro, NP-specific DTH effector cells cannot be evoked by conventional immunization regimens. This failure to induce hapten-specific DTH is not due to suppressor mechanisms. Attempts to induce LT production and T cell proliferation by re-exposure to NP were unsuccessful. Immunization with NP-coupled protein in CFA does elicit an intense Arthus reaction when mice are challenged with the hapten 8 days later. The antibody-mediated nature of this hapten-specific response is indicated by the kinetics of the reaction, which peaks 4 hr after challenge, intensely positive ELISA of circulating anti-NP antibodies, sensitivity to pretreatment with a high dose of cyclophosphamide, and the ability to transfer the reaction to naive recipients with serum. This early response is highly cross-reactive with NIP and is not restricted to mice of the igh-1b allotype.     

Antigen-specific T cell-mediated suppression. II. In vitro induction by I-J-coded L-glutamic acid50-L-tyrosine50 (GT)-specific T cell suppressor factor (GT-T8F) of suppressor T cells (T82) bearing distinct I-J determinants.

The induction of new suppressor T cells (Ts2) by suppressive extracts (TsF) from L-glutamic acid50L-tyrosine50 (GT) nonresponder mice was examined. Incubation of normal spleen cells with allogeneic GT-TsF for 2 days in vitro led to the generation of Ts2 cells able to suppress subsequent responses to the immunogen GT-methylated bovine serum albumin (GT-MBSA) in vivo. This induction occurred efficiently when TsF donor and target cells differed at all of H-2, including the I-J subregion. B10.BR (H-2k) GT-TsF, adsorbed on, then acid eluted from GT-Sepharose and anti-I-Jk [B10.A (3R) anti-B10.A (5R)]-Sepharose in a sequential fashion could induce BALB/c (H-2d) spleen cells to become Ts2 only if nanogram quantities of GT were added to the purified GT-TsF. This indicates a requirement for a molecule or molecular complex possessing both I-J determinants and antigen (GT)-binding specificity, together with GT itself, for Ts2 induction. The induced Ts2 are I-J+, since their function can be eliminated by treatment with anti-I-Jk plus C. These I-J determinants are coded for by the precursor of the Ts2 and do not represent passively adsorbed, I-J coded TsF, since anti-Ijk antiserum [(3R X DBA/2)F1 anti-5R] which cannot recognize the BALB/c (I-Jd) TsF used for induction still eliminates the activity of induced A/J (I-Jk) Ts2. These data provide further evidence for and information about the minimum of two T cells involved in antigen-specific suppressor T cell systems.     

Generation of suppressor T cells after local immunization with histocompatibility antigens

Subcutaneous (sc) hind-foot immunization (HFI) of mice with allogeneic spleen cells can induce a state of delayed-type hypersensitivity (DTH) as well as a state of suppression of DTH. This paper deals with the suppression induced by HFI. The state of suppression could be adoptively transferred by spleen cells and lymph node cells between Days 3 and 7 after HFI only. However, in the hind-foot-immunized mice the state of suppression lasted at least 25 days. The suppressor cells expressed the Thy-1+, Lyt-1-2+ phenotype and suppressed DTH antigen-specifically. The suppressor cells, however, also suppressed DTH responses to unrelated third-party alloantigens, provided the latter were administered during the induction of DTH together with the same alloantigens that were used for HFI. The HFI-induced T-suppressor cells suppressed the induction phase of DTH (i.e., the proliferative activity of the draining lymph node cells after secondary sc immunization), but not the expression phase of DTH (i.e., the activity of previously activated DTH effector T cells). H-2D compatibility between the donors of the HFI-induced T-suppressor cells and the recipients was required for the adoptive transfer of suppression. The differences in effect of local immunization versus systemic immunization on the induction and functional activity of T-suppressor cells are discussed.     

The immune response and the eye. I. The effects of monoclonal antibodies to T suppressor factors in anterior chamber-associated immune deviation (ACAID)

We report the effects of two monoclonal antibodies (mab) specific for murine T suppressor (Ts) factors (TsF) in anterior chamber (AC)-associated immune deviation (ACAID), as induced by AC inoculation of TNP-coupled syngeneic spleen cells (TNP-Spl). One mab (14-12) is specific for Ts effector factor and can block the induction of Ts cells in ACAID if given before or after AC injection of TNP-Spl. The other mab (14-30) is specific for Ts inducer factors and blocks suppression only after given after TNP-Spl. We also studied the surface phenotype of the Ts cells induced by AC injection of TNP-Spl. We show that at least two cells are required for the adoptive transfer of suppression in TNP-ACAID. One is Lyt-2+ and 14-12+, the other is I-J+. These Ts cells have the surface phenotype of Ts effector cells as seen in other systems. These results indicate that mab which bind TsF in other systems affect Ts cells in TNP-ACAID, and that the Ts cells induced in TNP-ACAID are only of the Ts effector type.     

Antigen-specific suppressor T cell interactions. I. Induction of an MHC-restricted suppressor factor specific for L-glutamic acid50-L-tyrosine50

The synthetic polymers L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) and L-glutamic acid50-L-tyrosine50 (GT) stimulate specific suppressor T cells in certain strains of mice. Extracts from these T cells contain factors (TsF) that inhibit GAT- or GT-specific antibody responses by normal spleen cells or proliferative responses by primed T cells. We constructed T cell hybridomas that constitutively produce GAT-TsF or GT-TsF, which functionally and serologically are identical to factors extracted from suppressor T cells. In this report we demonstrate that monoclonal GT-TsF can induce specific unresponsiveness in vivo or in vitro and that this unresponsiveness is due to development of second-order antigen-specific suppressor T cells. T cell hybridomas were constructed by fusion of BW5147 with GT-TsF1 induced second-order suppressor T cells and clones that produced suppressor factor (GT-TsF2) were isolated and characterized. GT-TsF2 differs from the GT-TsF1 used to induce it in that GT-TsF1 acts across allogeneic barriers whereas GT-TsF2 does not. This restriction is controlled by genes in the H-2 gene complex and maps to the I-J subregion. GT-TsF2 is antigen-specific in suppressive activity and also in its antigen-binding site(s). Thus, GT-TsF2 closely resembles the carrier-specific, I-J+, genetically restricted factor described by Tada and his colleagues. Because GT-TsF2 was induced by GT-TsF1, we suggest cells producing GT-TsF1 are an early cell in the pathway of suppression, and that this cell is required for the activation of antigen-specific, MHC-restricted TsF.     

The differential ability of splenic adherent cells from B6.lpr mice to induce suppressor T cells

Hapten-coupled splenic adherent cells or resident peritoneal cells from autoimmune B6.lpr mice that are over 5 mo of age fail to induce first-order inducer suppressor T cells (Ts1). However, the same population of hapten-coupled cells can induce both delayed-type hypersensitivity responses and third-order effector suppressor T cells (Ts3). Thus, splenic and peritoneal antigen-presenting cells from B6.lpr mice display a defined defect in the ability to induce certain suppressor T cell responses. The cellular defect in Ts1 induction is controlled by the lpr gene, since age-matched congenic B6 mice do not display this defect. The splenic adherent cell defect is temporarily correlated with the autoimmunity that develops in B6.lpr animals. The antigen-presenting defect in the B6.lpr splenic adherent population for Ts1 induction is reversible by culturing the cells in interferon-gamma. The results are discussed as an illustration of the relationship between experimental models of autoimmunity and defects in a suppressor T cell cascade.     

Epidermal cells in activation of suppressor lymphocytes: further characterization

Intravenous administration of hapten-coupled, high-density (density greater than 1.077) epidermal cells (HD-EC) to mice results in the appearance of transferable splenic T suppressor (Ts) cells as assayed in adoptive transfer experiments. Depletion of I-A bearing cells from the HD-EC population before hapten coupling prevents these cells from inducing Ts cell formation, whereas depletion of Thy-1-bearing cells from the HD-EC cell preparation has no effect. When HD-EC are adhered to glass for 2 hr, the ability to induce Ts cell formation resides in the adherent population. Exposure of HD-EC to a dose of ultraviolet radiation (UVR) that largely abrogates the ability of hapten-coupled EC to immunize mice for a DTH response does not affect the ability of these cells to activate Ts cells. Treatment of mice with i.p. administration of 20 mg/kg of cyclophosphamide 2 days before EC harvesting abrogates the ability of HD-EC from these mice to induce Ts cell formation. HD-EC from B10.A(3R) (I-Jb) but not B10.A(5R) (I-Jk) mice induce Ts cell formation in B10.A(3R) mice, demonstrating that the ability to do so is restricted by the I-J locus. Transmission electron microscopy of adherent HD-EC populations demonstrated that two cell types were present. One type had the characteristics of keratinocytes; the other was monocyte-like and resembled Langerhans cells or indeterminate cells in many aspects. Immunoelectron microscopy revealed this second cell type to bear I-A/I-E antigen. These cells were T-200 positive and Mac-1 negative by immunoperoxidase staining. Extensive examination by light and electron microscopy failed to reveal any dermal components in the EC populations; however, a very small degree of dermal contamination cannot be excluded. Thus, EC that activate afferent-acting Ts cells are high-density, I-A+, Thy-1-, I-J restricted, glass adherent, and functionally UVR resistant and cyclophosphamide sensitive.