T cell receptors with allo-major histocompatibility complex specificity from rat and mouse. Similarity of size, plasmin susceptibility, and localization of antigen-binding region.

Abstract

Antisera specific for the constant part Ctau of T cell receptor molecules in mice and rats have been produced in rabbits by immunization with idiotype-positive rat T cell molecules. Such antisera could be shown to react with the majority of normal T lymphocytes from both rats and mice. Mixed leukocyte culture-activated T blasts displayed a higher percentage of positive cells than concanovalin A- or phytohemaglutinin-induced T blasts. Lipopolysaccharide-induced B blasts were not reactive with the antiserum. Lyt-1-,2+,3+ blasts displayed a significantly brighter straining than the corresponding Lyt-1+,2-,3- blasts. Isolation of the reactive molecules from T cells by immunosorption yielded a 70,000-dalton single chain polypeptide as the dominant group of molecules. Plasmin caused the chain to split into 45,000- and 25,000-dalton polypeptides, with the smaller fragment displaying antigen-binding capacity. Molecules identical in size and plasma degradation patterns were isolated from Lyt-1+,2-3- and 1-,2+,3+ blasts. Preliminary functional data supported the view that the antiserum is directed against the constant region Ctau relevant receptor structures on immunocompetent T lymphocytes.

T cells produce an antigen-binding factor with in vivo activity analogous to IgE antibody.

“…Each of the 12 different preparations of PCLF used in this study, a preparation of OXF, and mouse Ig standards were coated onto the wells of plastic microtrays at a concentration of 100 ng/well. As described previously (7), none of the PCLF preparations, nor the OXF preparation, had Ig antigenic determinants detected by anti-x, -~, -/~, -a, -7, -6, or -E antisera, while all factor preparations had antigenic determinants detected by three different rabbit anlisera prepared against antigen-specific T cell factors from other systems (7,(14)(15)(16).…”

“…Since the IgE hybridoma antibody is very active in both assays, this suggests that the mechanism of mast cell activation by PCLF is different than the mechanism of mast cell activation by IgE. The active moiety in PCLF has a molecular weight of 70,000 or less (7), is derived from lymphoid cells depleted of B cells (7), has no Ig heavy or light chain antigenic determinants (7), and has antigenic determinants found on T cells and on antigenspecific T cell factors (7,(14)(15)(16). Despite these findings indicating that PCLF is T cell derived and not an Ig, the striking resemblence between the biologic activity of PCLF and IgE necessitated rigorous experiments to rule out the possibility that the active moiety in PCLF was due to contamination with IgE or that PCLF was a fragment or a potential subclass of IgE (24).…”

Definition of T cell idiotypes using anti-idiotypic antisera produced by immunization with T cell clones.

“…The antisera we produced appear to satisfy definitions of anti-idiotypic reagents. First, these antisera distinguish between alloreactive T cell clones (6-4 and 6°59 vs. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23], which should be identical except for their antigen receptors. The finding that clones 6-4 and 6-59 are both triggered by antisera to either clone suggests that they may be derived from the same clonal precursor, i.e., they may have identical antigen receptors.…”

The major histocompatibility complex-restricted antigen receptor on T cells. I. Isolation with a monoclonal antibody.

“…T cell products have been isolated using their ability to bind Ag and the various antisera mentioned above, and thus some preliminary biochemical data are available concerning these products. These proteins, usually suppressor factors, have molecular weights of ~70,000 (20)(21)(22)(23), although smaller molecules have been reported (16). The 70,000-tool wt proteins have been shown to be susceptible to proteolytic cleavage into smaller subunits of 25-30,000 and 45-50,000 mol wt (20)(21)(22)(23); the larger fragment possesses apparent functional activity and the smaller subunit may be the Ag-binding portion, although this may not always be so.…”