Mouse T-cell tumour immunoglobulin I. ANTIGENIC PROPERTIES AND EFFECTS ON T-CELL RESPONSES.

The mouse T-cell tumours El -4 and WEHI-22 produce an immunoglobulin (TCT Ig) which suppresses the antibody response to T- dependent antigens in vitro while having no effect on responses to T-independent antigens. TCT Ig also augments IgG responses to both kinds of antigen. TCT Ig appears to be a new class of mouse Ig because its effects on in vitro antibody responses can be absorbed by antisera to mouse Kappa chains but not with antisera to any of the known classes of mouse Ig. Furthermore, TCT Ig activity cannot be duplicated by free light chains, Fab₂ fragments, several mouse serum Ig preparations or Ig made from B cells. TCT Ig affects only T-cell function in antibody responses. It has no effect on the ability of the different subclasses of T cells to respond to mitogens or to alloantigens. Furthermore, it does not block T-T-cell co-operation suggesting that the molecular basis for T-T co-operation differs from that of T-B co-operations. [ABSTRACT FROM AUTHOR]