Physiology of IgD. VII. Induction of receptors for IgD on cloned T cells by IgD and interleukin 2
Coico, R.F.; Berzofsky, J.A.; York-Jolley, J.; Ozaki, S.; Siskind, G.W.; Thorbecke, G.J.
Journal of Immunology 138(1): 4-6
1987
ISSN/ISBN: 0022-1767 PMID: 2946779 Document Number: 303165
The role of IgD in the immune response has remained elusive, although the predominance of IgD on the B cell surface and the paucity of IgD in serum have suggested a receptor function. In support of this hypothesis, it has recently been shown that receptors for IgD on helper T cells can be induced by exposure to IgD in vivo and in vitro. Such IgD receptor-positive T cells (i.e., T delta cells), detectable as RFC using IgD-coated SRBC, augment antibody responses. In this report, we demonstrate that cloned, antigen-specific T cells of helper phenotype show only very low percentages of IgD-RFC, if allowed to rest in vitro after antigen exposure in the absence of IL 2. Exposure to IgD or to IL 2 for 24 hr causes the IgD-specific RFC to increase as much as 25-fold to nearly 80%. Clones that have recently been stimulated with antigen, or T cell hybridomas prepared from such clones, exhibit 40 to 50% IgD-RFC before exposure and twofold higher levels after exposure to IgD. IL 2 also causes a dose-dependent induction of OgD-RFC in normal splenic T cells. Thus, antigen stimulation, IL 2 and IgD can all induce these receptors for IgD which presumably enable helper T cells to interact more effectively with IgD+ B cells.