K Onoé

Identification of a peptide inducing experimental autoimmune uveoretinitis (EAU) in H-2Ak-carrying mice

When certain strains of mice bearing H‐2Ak are immunized with the interphotoreceptor retinoid‐binding protein (IRBP), EAU is induced. Thus far uveitogenic determinant(s) has not been determined in the H‐2Ak mouse system. In addition it is hard to prepare purified IRBP. In the present study, to circumvent these problems we attempted to identify uveitogenic peptides derived from bovine IRBP in H‐2Ak haplotype mice. Six peptides which had been selected according to the H‐2Ak binding motif (Dxxxxxxxx[A, R, T]) were synthesized. We report here that all the peptides are immunogenic but only one peptide, K2, which consisted of IRBP201–216 residues, induces EAU in various mice carrying H‐2Ak. Amino acid substitution of K2 revealed that the core region interacted with both H‐2Ak and T cell antigen receptor (TCR). The amino acid sequence of the core region derived from bovine IRBP was identical to the corresponding region of mouse IRBP. In addition, K2 appeared to be a natural peptide antigen processed from bovine IRBP. Altogether, we concluded that K2 is one of the natural autoantigens involved in induction of EAU in H‐2Ak mice.

Analyses of Ia Restriction Specificity of Helper T cells in H-2 Subregion Compatible Bone Marrow Chimera in Mice

Using irradiation bone marrow chimeras which had partial compatibility in H-2 subregions between donor and recipient mice, we found that H-2I matching was sufficient for the chimeras to generate anti-sheep erythrocyte plaque-forming cell (PFC) responses. In such chimeras, T cells appeared to encounter appropriate partner cells bearing the same Ia antigens as those which they had learned to recognize as self in the recipient micro-environment. Furthermore, the PFC number seen in I-A compatible chimeras was only about half of that seen in I-A, I-E compatible chimeras, suggesting the existence of two independent subpopulations of helper T cells. When incompatibility of donor and recipient mice existed on the left side of the H-2I region, the responses were very weak. However, even in such chimeras, marked responses were observed for both IgM and IgG type PFC following a sufficient period after immunization. This observation appears to indicate the existence of a minor subpopulation of helper T cells which can expand and interact effectively with antigen presenting cells of donor type.

Different influence of macrophage migration inhibitory factor (MIF) in signal transduction pathway of various T cell subsets.

It has been shown that macrophage migration inhibitory factor (MIF) modulates not only macrophage functions, but also T cell functions. However, detailed analysis of the MIF function on responses of various T cell subpopulations remained to be elucidated. In this report, using a neutralizing anti-MIF monoclonal antibody (mAb) we examined MIF functions on various T cell lineages. It was shown that anti-MIF mAb inhibited antigen-specific responses of both IFN-gamma producing and IL-4 producing T cells. The inhibition appeared to be related to blockade of the signal pathway via T cell receptor (TCR) but not that via IL-2 receptor (IL-2R). However, the anti-MIF mAb showed no inhibitory effect on NK-T cell responses stimulated through TCR. These results suggest that MIF is involved in the signal pathway via TCR in mainstream T cells but not in NK-T cells.

Analyses of H-2 restriction specificity of helper T cells in fully allogeneic bone marrow chimera in mice

Using irradiation bone marrow chimeras to analyze restriction specificity of helper T cells, we found that recipient H-2 type dictated the H-2 type which the T cells recognize as self (adaptive differentiation). T cells from (H-2b----H-2k) chimeras cooperate with non-T cells bearing Iak to generate a vigorous PFC response to sheep erythrocytes (SRBC) in vitro, but not with genetically identical H-2b cells. However, when T cells from the chimeras and H-2b non-T cells were adoptively transferred into irradiated (donor X recipient) F1 mice with SRBC, marked responses were seen in recipient spleens where radio-resistant F1 macrophages might exist and act as antigen presenting cells (APC). From these in vitro and in vivo observations, we considered that in the primary antibody response to a T dependent antigen such as SRBC, only T cell-macrophage (APC) matching is required. In contrast, when T cells from H-2 incompatible chimeras which had been primed with SRBC in vivo were analyzed in vitro, these cells cooperated also with H-2b non-T cells. These findings indicate that there may be two separate stages of T cell differentiation during which the self restriction specificity is acquired: one appears to be responsive to intrathymic influences and is not associated with antigenic stimuli, and the other shows signs of being responsive to post-thymic stimuli and of involving antigenic presentation. Moreover, the latter appears to utilize the influence of donor type macrophages.

A Study on Class II Antigens Involved in the T Cell Prorliferative Responses to PPD Using Cross-Reacting Monoclonal Antibodies in Human and Murine System

Two monoclonal antibodies (MoAb) 1E4 and ISCR3, which detect class II antigens across species barriers, were studied for their inhibitory effects on human and murine T cell proliferative responses to purified protein derivative of tuberculin (PPD). The 1E4 detected at least a polymorphic determinant on I-A molecules from mice carrying the H-2b haplotype, and the ISCR3 detected the Ia.7 determinant on I-E molecules. Nevertheless, both 1E4 and ISCR3 recognized monomorphic determinants on HLA-DR antigens (human I-E equivalent molecules), but not on HLA-DQ antigens (human I-A equivalent molecules). It was demonstrated that 1E4 significantly inhibited PPD-specific responses of T cells from Ib-bearing mice. In contrast, ISCR3 showed marginal effects on the responses of mice bearing Ia.7. However, in the human system both 1E4 and ISCR3 reduced proliferative responses to PPD. These results suggest that a functional difference exists between humans and mice in the I subregion products involved in the T cell proliferative responses to PPD.

Significant MLR but not CTL responses against recipient antigens generated in T cells from bone marrow chimeras recovered from acute GVHD

Lethally irradiated AKR mice received BMT from H-2D and minor lymphocyte stimulatory (Mls)-1 disparate B10.A mice. No GVHD signs were detected in AKR recipients of T cell-depleted BM cells (1 × 107) alone ([B10.A → AKR] T−). When B10.A splenic T cells (1 × 105) were injected in addition to T cell-depleted BM cells ([B10.A → AKR] T+), overt GVHD was observed. [B10.A → AKR] T+ chimeras recovered from the GVHD 8 weeks after BMT. In T cells from these [B10.A → AKR] T+ chimeras, a substantial population of Mls-1a-reactive Vβ6+ T cells was present, whereas the Vβ6+ cells were deleted in [B10.A → AKR] T− chimeras. T cells from [B10.A → AKR] T+ chimeras showed considerable MLR but no CTL response against AKR cells (split tolerance). Upon stimulation with AKR stimulators or anti-CD3 MoAb, T cells from [B10.A → AKR] T+ chimeras produced significantly more IL-4 but significantly less IFN-γ compared with those from [B10.A → AKR] T− chimeras or unmanipulated B10.A mice. The serum level of IgG1 in [B10.A → AKR] T+chimeras was also significantly higher than that in [B10.A → AKR] T− or B10.A mice. The present findings suggest that the split tolerance observed in BMT chimeras recovered from GVHD is attributable to the Th2 dominant state. Bone Marrow Transplantation (2000) 26, 1069–1076.

Effects of non-major histocompatibility antigens on acute graft-versus- host reaction after allogeneic bone marrow transplantation

In the present study using an experimental BMT system we analyzed the effects of disparity at non-MHC Ag including minor lymphocyte stimulatory-1a (Mls-1a) Ag on the acute GVH reaction (GVHR) induced by MHC class I Ag. Mismatch at MHC (class I) Ag alone did not induce clinically detectable acute GVHR in this model. However, BMT mice prepared with a combination of both class I and non-MHC Ag mismatches showed signs of clinical GVHR and various cytokines were produced by the spleen cells at an early stage (4 days) after BMT. Although no clinical GVHR was detected in BMT chimeras prepared with a non-MHC mismatched but MHC matched combination, large amounts of various cytokines were secreted by spleen cells. Cytokine production in the latter two kinds of chimeras paralleled the increase of Mls-1a reactive Vβ 6+ T cells in the host spleen. Marked cytokine production induced by Mls-1a Ag was confirmed by MLR. Thus, these cytokines appeared to be produced by T cells responding to Mls-1a (ie Vβ 6+ T cells) and to augment the T cell responses to MHC class I which resulted in clinically detectable GVHR in chimeras prepared with the combination mismatched at both MHC class I and non-MHC loci.

Generation of Cytotoxic T Lymphocyte esponses to Allo-H-2 Antigens in Allogeneic Bone Marrow Chimeras Histocompatible at the H-2 Subregions

The present study was performed to determine whether H-2 matching is required for full cytotoxic T lymphocyte (CTL) responses to allo-H-2 antigens in allogeneic bone marrow chimeric mice. A number of irradiated, bone marrow-reconstituted chimeras constructed from various combinations of marrow cells from B10 H-2 recombinant strains and AKR recipient mice were prepared. Spleen cells obtained from such chimeras and normal control mice were activated in vitro by culturing them with irradiated stimulator cells. It was shown that spleen cells from [4R----AKR], [(4R X 3R)F1----AKR] or [AQR----AKR] chimeras, which were histocompatible on the left hand-side of the H-21 subregion between donor and recipient mice, generated greater CTL activities than those that were seen with spleen cells of [3R----AKR] or [5R----AKR] chimeras, which were histoincompatible in this region. We were unable to demonstrate suppressor cell activity of the spleen cells of [3R----AKR] chimeras cultured with stimulator cells. Although spleen cells from [3R----AKR] chimeras showed substantial proliferative responses to stimulator cells (MLR) and to Con A and LPS, IL2 activities of supernatants from Con A-activated spleen cells (Con A SN) of the chimeras were significantly lower than those of [4R----AKR] or [(4R X 3R)F1----AKR] chimeras. Furthermore, vigorous CTL activities were obtained with either spleen cells or thymocytes from [3R----AKR] chimeras when rat Con A SN was added to the MLR cultures. These observations suggest that the numbers of precursor CTLs in the cells from [3R----AKR] chimeras are at the same level as those of [(4R X 3R)F1----AKR] or normal mice and that the low CTL activities generated by spleen cells of [3R----AKR] chimeras compared to H-2I-matched chimeras are due in large measure to deficiency in IL2 production by the splenic T cells of the [3R----AKR] chimeras.

Sequential changes of the T Lymphocytes followingER Rosette formation in guinea pigs. I. Expression of Fc and Complement Receptors

Changes in proportions of the Fc and complement receptor (FcR, CR) positive T lymphocytes from guinea pigs following their interaction with rabbit erythrocytes (ER) were studied using EA and EAC rosette forming assays. Significant increases in the percentages of EA and EAC rosette forming cell (RFC) were observed when thymocytes or lymph node cells were assayed after ER rosette formation. Furthermore, T-enriched fraction by the ER monolayer adherence technique also showed similar or somewhat higher increases in the proportions of both EA and EAC RFC than those of unfractionated cells after contact with ER. The double rosette assay by ER with EA or EAC showed that 50-80% of the Fc and/or complement receptor positive lymphocytes bound rabbit erythrocytes simultaneously. These findings strongly suggest that at least a subset of the guinea pig T cells is altered to express Fc and/or complement receptors on their surfaces following the interaction with ER.