EXTRATHYMIC ORIGIN OF INTESTINAL INTRAEPITHELIAL LYMPHOCYTES BEARING T-CELL ANTIGEN RECEPTOR-GAMMA-DELTA

The kinetics of postanatal intestinal colonization by T cells carrying gamma-delta and alpha-beta T-cell antigen receptors were studied in nude and normal mice by flow cytometry and immunohistology. Furthermore, gamma-delta and alpha-beta T-cell development was analyzed in lethally irradiated mice that were reconstituted by fetal liver precursors with or without a thymus. Our results establish that a major subpopulation of gamma-delta intestinal intraepithelial lymphocytes is produced from uncommitted precursors at extrathymic sites. This work further shows that a small pool of T cells carrying alpha-beta T-cell receptors can also differentiate extrathymically from CD3- fetal liver precursors but with rates of production and peripheral expansion much reduced as compared with those observed in thymus-bearing animals.