DIFFERENTIAL DISTRIBUTION OF GAMMA-DELTA-T-CELL RECEPTOR LYMPHOCYTE SUBPOPULATIONS IN BLOOD AND SPLEEN OF YOUNG AND ADULT CATTLE

A panel of monoclonal antibodies to bovine leukocyte differentiation m olecules was used to evaluate peripheral blood and splenic lymphocytes from cattle of various ages. The major population of peripheral blood lymphocytes from neonatal calves was gamma delta T-cell receptor (TCR 1) positive, as determined by TCR1-N12 expression. TCR1-N12(+) lymphoc ytes were decreased in number in older calves, and were lowest in adul t cattle. The major subpopulation of TCR1-N12(+) cells from peripheral blood coexpressed WC1, but not BoCD2. A small subpopulation of periph eral blood TCR1-N 12(+) cells from cattle of all ages coexpressed BoCD 2, but not WC1. The TCR1-N12(+)BoCD2(+) lymphocytes made up the larges t TCR1-N12(+) lymphocyte subpopulation in spleens of both calves and a dults. The TCR1-N12(+)WC1(+) + splenic lymphocytes were present as a s mall population. The data indicate that two subpopulations of TCR1(+) lymphocytes are present in cattle of all ages. These two subpopulation s are differentially distributed between blood and spleen, with TCR1-N 12(+)WC1(+) lymphocytes predominating in blood, and TCR1-N12(+)BoCD2() cells predominating in spleen.