"I-J" as an idiotypic marker on the antigen-specific suppressor T cell factor

Ia restriction specificity of KLH-specific T cells from allogeneic bone marrow chimeras is influenced by histocompatibility at the H-2 and minor histocompatibility loci

Ia restriction specificity involved in T cell proliferative responses to keyhole limpet hemocyanin (KLH) has been analyzed using a variety of allogeneic bone marrow chimeras. The chimeric mice were prepared by reconstituting irradiated AKR, SJL, B10.BR and B10.A(4R) mice with bone marrow cells from B10 mice. When such chimeric mice had first been primed with KLH in complete Freund's adjuvant (CFA), T cells from H-2 incompatible fully allogeneic chimeras showed significantly higher responses to KLH in the presence of antigen-presenting cells (APC) of donor strain (B10) than APC of recipient strain. However, in H-2 subregion compatible chimeras, [B10----B10.A(4R)], which were matched at the H-2D locus and at minor histocompatible loci, the T cells could mount vigorous responses to KLH with antigen-presenting cells (APC) of either donor or recipient type. The same results were obtained as well with chimeras that had been thymectomized after full reconstitution of lymphoid tissues by donor-derived cells. A considerable proportion of KLH-specific T cell hybridomas established from [B10----B10.A(4R)] chimeras exhibited both I-Ab and I-Ak restriction specificities. The present findings indicate that the bias to donor Ia type of antigen specific T cells is determined by donor-derived APC present in the extrathymic environment but that cross-reactivity to the recipient Ia is influenced to some degree by histocompatibility between donor and recipient mice, even though the histocompatible H-2D locus and minor histocompatibility loci seem not to be directly involved in the I-A restricted responses studied herein.

Homogenous junctional sequence of the V14+ T-cell antigen receptor alpha chain expanded in unprimed mice

Nucleotide sequences of VJ (variable-joining) junctional regions of V14+ alpha-chain T-cell receptor genes show that most V alpha 14+ T cells use one alpha chain (V alpha 14J alpha 281 with a one-nucleotide N region, which is frequently used in keyhole limpet hemocyanin-specific suppressor T-cell hybridomas) in unprimed mice. Moreover, the frequency of this alpha-chain expression was greater than 1.5% of the total alpha chains found in laboratory strains, including B10 congenic mice. This is about 10(4) times higher than was expected. The V14J281 alpha-chain expression was relatively low but was significant in CD4+/CD8+ immature thymocytes and became quite high in mature single-positive T cells, implying that this alpha chain is selected during T-cell maturation. V14J281 expression increased with time after birth and reached a maximum at around 5 weeks of age. The ligand seems to be a self molecule and to be present in laboratory strains but to be absent in a wild mouse, Mus musculus molossinus, because bone marrow chimeras clearly showed that bone marrow cells derived from Mus musculus molossinus negative for this alpha chain raised V14J281-positive T cells in a C57BL/6 environment. The above results suggest that there are some selection mechanisms for this cell type other than those for conventional alpha beta T cells and also that the homogenous VJ junction of the V14J281 alpha chain plays a pivotal role in the selection of the T cell and its ligand reactivity.

General considerations in the interpretation of I-J genetic restrictions: evidence that the antigen-binding chain of antigen-specific T-suppressor factor has two recognition sites for members of the I-J hierarchy

(CBA X B10)F1 [(H-2k X H-2b)] mice produce two types of antigen-specific T-suppressor factor (TsF), which can be separated by affinity chromatography on anti-I-J monoclonal antibody. After reduction and alkylation, both chains of F1 TsF are required for biological activity. However, the antigen-binding chain (AgBC) of F1 TgFk (AgBCk) is only complemented by I-Jk and likewise for F1 TsFb. In other words, interchain complementation shows the same genetic restriction in interchain complementation in parental and F1 mice. F1 TsF bearing, for example, I-Jk (TsFk), interacts with haptenized 'antigen-presenting cells' ('APC') and parental I-Jk chains interacts with haptenized 'APC' of both parental haplotypes (dual reactivity). In contrast, the combination of parental AgBCb and F1 I-Jb shows single reactivity and only interacts with haptenized 'APCb'. It was inferred that the antigen-binding chain is responsible for the dual reactivity and, hence, for the interaction with a member of the I-J hierarchy on the 'APC'. It was concluded that the antigen-binding chain of TsF has two recognition sites for members of the I-J hierarchy--one for interchain complementation and the other for interaction with the haptenized 'antigen-presenting cell'. The term member of the I-J hierarchy is used instead of I-J because it is not clear whether the AgBC interacts with I-J or a receptor for I-J, or indeed a receptor for that receptor.

Sequence and expression of transcripts of the T-cell antigen receptor alpha-chain gene in a functional, antigen-specific suppressor-T-cell hybridoma

We have detected rearrangement and expression of a gene encoding a T-cell antigen receptor alpha chain in the keyhole limpet hemocyanin (KLH)-specific, inducible suppressor-T-cell (Ts) hybridoma 34S-281 (BW5147 lymphoma-C57BL/6Ts) by using alpha-chain cDNA clones isolated from this Ts hybridoma. The cDNA clones have a restriction length polymorphism in the constant region that identifies them as being of C57BL/6 origin. The cDNA sequence has an ATG start codon for an open reading frame including variable, joining, and constant gene segments. Furthermore, the Ts alpha-chain gene transcripts were detected on membrane-bound polysomes by RNA blot analysis using a variable-region fragment from one of the alpha-chain cDNA clones as probe, suggesting that they are actively translated in the Ts hybridoma. As the beta-chain gene is deleted in all Ts hybridomas analyzed, and since a disulfide-linked dimer is detectable by two-dimensional NaDodSO4/PAGE of lysates of surface-radioiodinated Ts, we suggest that Ts antigen receptors are either alpha-chain homodimers or heterodimers composed of the alpha chain in association with an undefined chain.

Altered I-J phenotype in E alpha transgenic mice

One of the more intriguing puzzles in immunology is the genetic basis for control of murine T-cell I-J determinants. Molecules bearing I-J determinants (I-J molecules) play a role in information trafficking among immunocompetent cells, probably serving as self-recognition molecules that channel regulatory factors to their appropriate target cells. Although it is clear that I-J polymorphism is influenced by the major histocompatibility complex (MHC), molecular genetic studies provide evidence that an MHC gene does not encode I-J molecules. A possible explanation for this paradox is that I-J molecules are a set of non-MHC-encoded T cell receptors that are directly or indirectly selected for by self-MHC products. One key to resolving the genetic and molecular basis for control of I-J determinants is the identification of the MHC gene(s) involved. Herein, data are presented which show that E alpha transgenic mice express an altered I-J phenotype, providing clear evidence that I region class II genes influence I-J polymorphism. Although further study is required to resolve how class II genes mediate this effect, this is a major piece to the I-J puzzle.

Cell-cell interaction responsible for the induction of first order suppressor T cells in hapten-specific contact sensitivity reactions

C3H/He mice were found to be low responders in the contact sensitivity response to ABA. Intravenous injection of ABA-coupled syngeneic spleen cells induced hapten-specific Ts in C3H/He mice. These cells were Ts1 because they acted on the inductive phase of the contact sensitivity. They could suppress the contact sensitivity in H-2-compatible CBA mice which were known to be high responders to ABA. Using in vivo and in vitro systems for the induction of Ts, it was shown that I-A-I-J+Thy-1- adherent cells were necessary as APC for the induction of Ts1.