The immunoglobulin-like T cell receptor--IV. Quantitative cellular assay and partial characterization of a heavy chain cross-reactive with the Fd fragment of serum mu chain

Antigenic cross-reactions among immunoglobulin of diverse vertebrates (elasmobranchs to man) detected using xenoantisera

1. Antisera raised in rabbits and goats against intact immunoglobulins or their constituent light and heavy chains from man, mouse and the galapagos shark (Carcharhinus galapagenesis) were tested for their reactivity with immunoglobulins of elasmobranchs, other lower vertebrates and eutherian and prototherian mammals. 2. Xenoantisera directed against human heavy chain isotypes allowed the serological identification of IgM and IgG immunoglobulins in the echidna (Tachyglossus aculeatus), a monotreme which is one of the most primitive species of extant mammals. 3. The antisera to heavy chains reacted to varying degrees with purified immunoglobulins of non-mammalian species, including the chicken, teleost fish and elasmobranchs in a fashion that was specific for immunoglobulins, but was not related to defined human isotypic markers. 4. The reactions of some antisera seem to skip species known to possess homologous immunoglobulins. 5. Antisera directed against isotypic markers of human kappa and lambda light chains reacted with shark light chains in a manner that was specific for light chain determinants but was not isotype-related. 6. Antisera directed against heavy chains of either sharks or mammals reacted with heavy chains, but not with light chains of diverse species. 7. A rabbit antiserum specific for shark light chain reacted with human and murine monoclonal lambda chains and with two synthetic peptides corresponding to human V lambda Fr3 and Fr4 sequences. 8. These results establish that a variety of antigenic markers including conformational and linear determinants can be shared among immunoglobulins of vertebrates species that had an ancestral divergence more than 400 million years ago.

Antigenic mapping of a human lambda light chain: correlation with three dimensional structure

Although the amino acid sequence and three-dimensional structure of human immunoglobulin light chains have been known for more than 15 years, the location of antigenic markers characteristic of lambda chains has not been determined. Here, we use a set of synthetic overlapping peptides to completely model the sequence of the lambda chain Mcg and test these for the binding of rabbit and goat antisera specific for lambda chain determinants. We assess peptide contributions to lambda-antigenic reactivity and also to identify a portion of C-region where conformational factors contribute to the antigenicity. Specific determinants occur both in the constant and variable (first and third framework) domains of the molecule. The fourth framework of the variable region, a segment specified by the joining gene, is also recognized and cross-reacts antigenically with the homologous region of T cell receptor beta chains. Major lambda specific determinants are localized in the N- and C-terminal segments, which are linear and devoid of major conformational folding. Other segments that are strongly antigenic, such as the third framework of the V region (residue 78-93) and a segment of the constant region (residues 177-192), show strong conformational dependence in antigenicity.

Some T-cell leukemia lines express surface markers related to a restricted set of human VH determinants

Serological studies were carried out to obtain information regarding the relationship of the VH-related determinants expressed by certain permanent in vitro T-cell leukemia lines and corresponding determinants expressed by characterized human serum immunoglobulins. A panel of conventional (goat and rabbit) antisera, produced against various Fab-related fragments of monoclonal human Waldenstrom macroglobulins and polyclonal IgG molecules, bound to certain in vitro T-cell leukemia lines, notably, 70-N2, MT-1, YT4E, and HUT78, as shown by microhemagglutination. Inhibition studies using characterized myeloma proteins to inhibit this agglutination indicated the expression of a restricted VH-related determinant by these T-cell lines. Parallel studies performed using conventional (rabbit) and murine monoclonal/hybridoma antibodies produced against the isolated 68,000-Da VH-related product synthesized by the 70-N2 line showed that the determinant expressed by this molecule was restricted in expression, comprising 2-3% of the normal, polyclonal human Fab pool, and that the determinants found on the other positive T-cell leukemias were cross-reactive rather than identical. The inhibition studies suggest that the determinant resides between residue 22 and the end of the VH region. These results further define the antigenic nature of the VH-related marker found on the surfaces of certain normal and neoplastic T-cell lines.

A marmoset T-lymphocyte protein related to defined human serum immunoglobulin and fragments

Current concepts of the antigen-specific receptor of thymus-derived (T) lymphocytes suggest that this molecule bears immunoglobulin (Ig) variable (V) regions, but does not represent a classical serum antibody. We immunized rabbits with a globulin fraction obtained from an in vitro cultured marmoset T cell lymphoma line which expressed surface components related to immunoglobulins. Quantitative immunoprecipitation and competition radioimmunoassay studies carried out using characterized monoclonal human Igs and their chains and fragments show that this rabbit antiserum, raised against a T cell product, reacts with a particular, conformational VH-determinant which is formed by interaction with lambda light chains and with two mu chain (IgM) related determinants. Neither mu chain determinant is a major isotype specific marker, and each occurs only on certain distinct subsets of serum mu chains. One is located in the Fc fragment; the location of the other mu related determinant is not known. These results show that this rabbit antiserum recognizes both variable and constant region determinants on the T cell receptor heavy chain. Rabbit antibody to the T cell product which cross-reacts with serum mu chain was isolated by immune affinity chromatography on Sepharose-derivatized covalently with one particular reactive IgM protein, the Waldenstrom macroglobulin Can (kappa mu). This antibody precipitated a biosynthetically-labelled component of approximate M.W. 70,000 as assessed by polyacrylamide gel electrophoresis in Na Dod SO4-containing buffers. These data support the conclusion that certain T cells express and synthesize a molecule related to Ig VH-regions which also has a constant region sharing antigenic markers with IgM subpopulations.