Intestinal T lymphocytes in the chicken express an integrin‐like antigen

Abstract

We report the characterization of a molecule recognized on chicken T cells by the murine A19 monoclonal antibody that was generated by immunization with intestinal intraepithelial lymphocytes. Immunofluorescence analysis indicated that both αβ and γδ T cell subpopulations in the intestine express the A19 antigen, but natural killer cells and B cells do not. The A19‐marked T cells were preferentially localized in the intestinal epithelium and less frequently in the underlying lamina proprial, T cells appearing in the intestine during embryonic life were A19 negative but acquired the antigen within the first few days after hatching. Although rarely found on cells in non‐intestinal tissues at any age, very late expression of the A19 antigen could be induced by concanavalin A stimulation of splenic and circulating T cells. Transforming growth factor β1 enhanced this induction of A19 expression. The A19 molecules expressed by intestinal T cells and activated splenic T cells were biochemically identical, consisting of a multi‐molecular complex of proteins with approximate M_r of 205, 145 and 75 kDa under nonreducing conditions and 120, 90 and 28 kDa under reducing conditions. The characteristics of this multimolecular complex and its differential expression suggest that the A19 antigen is a member of the integrin family which may function in the retention of intestinal lymphocytes.