THYMUS-DEPENDENT AND THYMUS-INDEPENDENT SUB-POPULATIONS OF INTESTINAL INTRA-EPITHELIAL LYMPHOCYTES - GRANULAR SUB-POPULATION OF PROBABLE BONE-MARROW ORIGIN AND RELATIONSHIP TO MUCOSAL MAST-CELLS

Abstract

Intraepithelial lymphocytes were examined histochemically in the small intestines of normal rats and mice and in thymus-deficient animals (B [bone marrow reconstituted] rats and nude mice). These cells are heterogeneous, consisting of at least 2 subpopulations. One population contains granules, is thymus-independent and is probably bone marrow-derived. The other population does not contain granules and appears to be thymus-dependent. The granular cell, which may be a precursor of mucosal mast cells, is apparently more properly a previously unrecognized nonlymphoid leukocyte of bone marrow origin.