Limiting Dilution Analysis of Functional T Cells in the Gut Mucosa

Abstract

The function, nature and derivation of the lymphoid cells which are found in the gut epithelium remains controversial. In man, there is little doubt that virtually all intraepithelial lymphocytes (IEL) are of the T cell lineage because most of them are recognized by monoclonal antibodies specific for the T3 antigen complex associated with the T cell receptor (1,2). Functional data on these cells is, however, completely lacking. In rodents, the situation is much less clear because IEL have not been tested for the expression of T cell receptor related antigens and because of a body of evidence that many IEL are thymus-independent, contain granules and are Thy-1^- (3–6). Indeed, we have recently shown by limiting dilution analysis that 1 in about 170 of normal mouse IEL are mast cell precursors, and that the frequency can reach as high as 1 in 60 if the mice are worm infected (7).