T Cells Expressing the Vβ1 T-Cell Receptor are Required for IgA Production in the Chicken

While αβ T cells in mammals may express one of many variable (V) gene families in the β locus, chickens have only two Vβgene families. The avian Vβ2+T cells are recognized by the T-cell receptor 3 (TCR3) monoclonal antibody and Vβ1+T cells are recognized by the TCR2 antibody, which we used to selectively suppress development of Vβ1+T cells in order to examine their functional role. Suppression was accomplished by multiple injections of anti-TCR2 antibodies beginning in embryonic life and perpetuated by thymectomy 8 days after hatching. Young birds thus depleted of Vβ1+T cells had greater than normal numbers of Vβ2+T cells and appeared as healthy as thymectomized and untreated controls. While production of IgM and IgG antibodies was unimpaired, IgA antibody production was severely compromised in the Vβ1-depleted birds. The levels of secretory IgA in bile and lung lavage fluid were reduced 1000- to 10,000-fold and secretory IgA antibodies were not produced in response to mucosal immunization. B-cell production of IgA antibodies thus appears to require T cells expressing the Vβ1 genes, whereas T cells that express the Vβ2 genes lack this capacity.