Differential major histocompatibility complex-related activation of idiotypic suppressor T cells. Suppressor T cells cross-reactive to two distantly related lysozymes are not induced by one of them

The distinctive specificity of antigen-specific suppressor T cells

Although suppressor T cells have been cloned in only a few instances, the existence of a functional cadre of T cells that acts to downregulate the immune response is well documented. In this review Eli Sercarz and Urszula Krzych describe studies on suppressor T-cell (TS-cell) specificity that provide some support for the conclusion that the TS cell is a distinctive cell type with an expressed repertoire that is different from that expressed by helper T (TH) cells. They go on to explore the interaction between cells recognizing TS-cell-inducing determinants (SDs) and TH-cell-inducing determinants (HDs), and their relationship to immunogenicity and Ir gene effects.

Selective reversal of H-2-linked genetic unresponsiveness to lysozymes. II. Alteration in the T helper/T suppressor balance, owing to gene(s) linked to Ir-2, leads to responsiveness in BALB.B

Immune responsiveness to lysozyme in H-2b mice is under the control of H-2-linked Ir genes, with T suppressor (Ts) cells playing a dominant role in strains such as C57BL/6 (B6), C57BL/10 and A.BY. However, non-H-2-genes were found to be capable of specific reversal of the effect of the H-2-linked genes in responsiveness to chicken lysozyme (HEL), but not to human lysozyme (HUL). Therefore, studies were performed to identify any lesion in the suppressor circuit in BALB.B. It was known that HUL-induced suppressor cells could cross-suppress the anti-HEL response in B10.Q mice, which are responsive to HEL but nonresponsive to HUL. Similarly, BALB.B Ts cells were able to suppress the anti-HEL response, using as T helper (Th) source a T cell line (BB-1), derived from HEL-primed BALB.B periaortic and inguinal lymph node cells. A protocol designed to examine the in vivo suppression by the use of HUL-induced suppressor cells also demonstrated a significant suppression of the anti-HEL response. Since the suppressive circuitry seemed intact in the BALB.B, the possibility was examined that a step in T-B cell collaboration was more efficient in this strain than in the B6 nonresponder. With a B6-derived HEL-specific T cell line, BO1H, the B cell and antigen-presenting (B/APC) populations from B6 required addition of concanavalin A supernatant for anti-HEL antibody formation, whereas BALB.B B/APC were capable of responding to HEL in culture without the addition of concanavalin A supernatant. In agreement with this finding, when B/APC cell populations from BALB.B and B6 were compared for their extent of anti-HEL responsiveness, as measured with BB-1 Th cells, BALB.B B/APC populations responded significantly higher than B6 populations when the responses were activated by picogram/nanogram amounts of HEL. The response level of (BALB.B X B6)F1 B/APC measured in the same assay resembled that of B6. However, when HEL was used at the microgram level, both B6 and BALB.B strains responded equivalently. The above data are consistent with the expression of the reversing non-H-2 Ir gene(s) resulting from the balance of antigen presentation to Th and Ts cells in the H-2b mouse. In the B6, processing and handling of antigen may be inefficient in activating response-enhancing Th, and more effective in triggering Ts cells, while the reverse may be true for the BALB.B.

Immunoregulation of lysozyme-specific suppression. I. Induction and suppression of delayed-type hypersensitivity to hen egg-white lysozyme

Subcutaneous immunization with hen egg-white lysozyme (HEL) in complete Freund's adjuvant induces, both in antibody responder and nonresponder mice, a classical delayed-type hypersensitivity (DTH) reaction evaluated as footpad swelling. This response can be specifically transferred to naive recipients by Lyt-1+2- T cells and passive transfer is restricted by genes mapping in or to the left of the I-A region of the H-2 complex. Fine antigenic specificity analysis shows that HEL-primed T cells mediating DTH recognize ring-necked pheasant egg-white lysozyme, a lysozyme closely related to HEL, but fail to respond to human lysozyme, differing from HEL at 40% amino acid residues. Complete cross-reactivity between native and denaturated (reduced and carboxymethylated) HEL is exhibited by T cells involved in the DTH response. Subcutaneous injection of HEL coupled to spleen cells is also able to induce antigen-specific and genetically restricted DTH responses whereas the same cells administered by i.v. or i.p. route induce predominantly suppressor T cell activation. These suppressor T cells specifically inhibit the induction phase of DTH reactivity to HEL.

Immunoregulation of lysozyme-specific suppression. II. Hen egg-white lysozyme-specific monoclonal suppressor T cell factor suppresses the afferent phase of delayed-type hypersensitivity and induces second-order suppressor T cells

Culture supernatant from a monoclonal T cell lymphoma line (LH8-105) obtained by radiation leukemia virus-induced transformation of hen egg-white lysozyme (HEL)-specific suppressor T lymphocytes is able, when injected into mice, to specifically suppress the delayed-type hypersensitivity (DTH) reaction induced by HEL. The suppressor T cell factor (TsF) exhibits fine antigenic specificity since it suppresses the DTH response induced by HEL without affecting the DTH response induced by ring-necked pheasant egg-white lysozyme (REL), a lysozyme closely related to HEL. Conversely, LH8-105 TsF is able to suppress the DTH response induced by human lysozyme, distantly related to HEL but sharing a common epitope critical for induction of suppressive activity. The fine antigenic specificity of LH8-105 TsF for a restricted epitope on the HEL molecule is confirmed by binding to HEL but not to REL immunosorbents. This TsF also bears I-J determinants, as demonstrated by binding to monoclonal anti-I-J immunosorbents, and it suppresses the afferent but not the efferent phase of the DTH response to HEL. The afferent suppression is controlled by genes apparently mapping in the I-J subregion of the H-2 complex since I-J-incompatible mice are not suppressed by LH8-105 TsF injection. This inducer-type TsF induces second-order effector suppressor T cells only in HEL-primed mice indicating the primary role of antigen, in association with H-2 (I-J) products, in the afferent portion of this suppressive circuit.

Monoclonal suppressor T-cell factor displaying V H restriction and fine antigenic specificity

The production of stable T-cell clones is essential for the study of T-cell-derived, specific immunoregulatory products and of specific T-cell receptors. T-cell clones have been established by radiation leukaemia virus (RadLV)-induced transformation of suppressor T lymphocytes specific for hen egg white lysozyme (HEL). We report here that culture supernatant obtained from these T-cell clones can, when injected into mice, specifically suppress the anti-HEL antibody response. This monoclonal T-cell product suppresses the antibody response induced by HEL and human lysozyme, but not that induced by ring-necked pheasant egg white lysozyme (REL), thus displaying fine antigenic specificity probably restricted to an epitope involving phenylalanine at amino acid residue 3, present in the N-terminal region of HEL and shared by human lysozyme but absent in REL. The suppression induced by this monoclonal T-cell product is restricted by both H-2 and Igh-1 genes whereas anti-HEL antibodies bearing a predominant idiotype are induced in all mice strains tested, irrespective of their H-2 haplotype or Igh-1 allotype.

H-2-determined kinetic differences for the induction of nucleoside-specific suppression

The kinetic and the H-2 requirements for the induction of nucleoside-specific suppression were examined in several strains of mice; specifically, whether adenosine (A)-coupled spleen cells given intravenously suppress the primary response to adenosine-KLH. The adenosine system was chosen because C57Bl/6 mice were originally found to be resistant to immune suppression when challenged 5 days after treatment with adenosine-coupled spleen cells. (Raps et al. J. Immunol. 126, 1542, 1981.) It was determined (i) whether A-specific nonresponsiveness is inducible in strains other than C57Bl/6; (ii) whether changes in hapten density on the A-conjugated spleen cells could alter C57Bl/6s ability to become nonresponsive, and (iii) whether there are interstrain differences in the time required to induce A-specific suppressor T cells (Ts). The results show that there are H-2-associated differences in the time required to induce A-specific immune suppression. While A-spleen cells failed to suppress the A-specific response in C67Bl/10 (H-2b), they did induce unresponsiveness in B10.D2 (H-2d on C57Bl/10 background). A 2.5-fold increase in epitope density of adenosine on cells did not influence the kinetics of suppression. C67Bl/6 were resistant to suppression on Day 5, but like the CB6F1, susceptible to unresponsiveness 10 days after treatment. Nonresponsiveness was T-cell-mediated and transferable across IgH-V barriers. Suppression induced by Balb/c donor mice is transferable to Igh-incompatible CAL-20 mice. These results are discussed in the context of genetic restrictions which regulate suppressor T-cell interactions.

Fine antigenic specificity and genetic restriction of lysozyme-specific suppressor T cell factor produced by radiation leukemia virus-transformed suppressor T cells

Culture supernatants obtained from a radiation leukemia virus-transformed, hen egg-white lysozyme (HEL)-specific, suppressor T cell line are able, when injected into mice, to specifically suppress the anti-HEL antibody response. Suppression is observed on both primary and secondary anti-HEL antibody responses evaluated by direct and developed hemolytic plaque assays. Culture supernatants from this HEL-specific suppressor T cell line do not suppress the antibody response induced by a structurally related lysozyme, demonstrating the presence in the culture supernatant of a suppressor factor endowed with fine antigenic specificity. The suppressor factor is able to selectively suppress the anti-HEL antibody response induced by the N-terminal C-terminal peptide of the HEL molecule indicating that the fine specificity of this factor is restricted to an antigenic epitope present in this region of the HEL molecule. The suppressive activity is restricted by genes located within the H-2 complex and analysis of the suppression induced in recombinant mice demonstrates that the interaction between HEL-specific suppressor T cell factor and its cellular target requires identity in the I-J region of the H-2 complex.