PHENOTYPE, AND MIGRATION PROPERTIES OF 3 MAJOR SUBSETS OF TISSUE HOMING T-CELLS IN SHEEP

T cells show a bias in their migration pathways: some T cells preferen tially migrate to peripheral lymph nodes (LN), some to mucosal tissues , and some to peripheral tissues such as skin. These recirculation pat hways were examined in sheep by collecting lymph draining into and out of peripheral and intestinal LN, and using fluorescent dyes to trace the recirculation of the lymph cells. Monoclonal antibodies (mAb) to a lpha 4, beta 1, and beta 7 integrins, and L-selectin, were used to def ine three major populations of recirculating T cells. Naive-type T cel ls (L-selectin(+), alpha 4 beta 1(lo)beta 7(lo)) migrated preferential ly through peripheral LN. Two memory populations could be defined: alp ha 4 beta 1(hi)beta 7(-) and alpha 4 beta 7(hi)beta 1(lo). alpha 4 bet a 1(hi)beta 7(-) T cells were present in lymph draining from the skin. T cells migrating preferentially through intestinal LN were alpha 4 b eta 7(hi)beta 1(lo). Consistent with this migration pattern, the endot helial receptor for alpha 4 beta 7, mucosal addressin cell adhesion mo lecule-1 (MAdCAM-1) was detected on high endothelial venules within in testinal LN and Peyer's patches, but only weakly on high endothelial v enules within peripheral LN. Thus, there are at least three easily def inable subsets of T cells, based on integrin expression, which show di stinct migration preferences.