OLIGOCLONALITY AND SKEWED T-CELL RECEPTOR V-BETA GENE SEGMENT EXPRESSION IN IN-VIVO ACTIVATED HUMAN INTESTINAL INTRAEPITHELIAL T-LYMPHOCYTES

Intraepithelial intestinal T lymhocytes (IEL) bearing alpha beta or ga mma delta T cell receptors (TCR) are positioned to serve as a first li ne of defense against enteric pathogens. To investigate whether intest inal IEL are subject to antigenic selective forces distinct from that influencing (xp T cells in the peripheral blood (PBL), we performed a comparative analysis of V beta gene segment usage in IEL and PBL of im munologically normal donors by quantitative PCR. Primers for 22 differ ent human TCR V beta gene segments of V beta gene segments families we re used to analyze the repertoire of TCR beta chain transcripts in col onic IEL (c-IEL), in corresponding colonic lamina propria lymphocytes (c-LPL), and in peripheral blood lymphocytes. In each of the three ind ividuals examined, a limited number (1-4 out of 22) of TCR V beta fami lies predominated and accounted for more than 50% of the total beta ch ain transcripts from c-IEL, whereas in PBL and c-LPL a more even distr ibution of V beta gene families was observed. The dominating VB gene f amilies were V beta 2, V beta 3, V beta 6, V beta 8 and V beta 14. In one individual, V beta 3 comprised more than 40% of the entire reperto ire of c-IEL beta chain transcripts. Sequence analysis of the predomin ant V beta 3 family in this individual revealed identical sequences in 13 of 17 clones analyzed. Human alpha beta TCR(+) c-IEL could not be driven to proliferate or exhibit cytotoxic function in vitro however, PCR analysis for detection of lymphokine mRNA revealed constitutive pr oduction of several lymphokines known to exert trophic effects on inte stinal epithelial cells and pro-inflammatory activities. Taken togethe r, the striking degree of oligoclonal