Characterization and distribution of lymphocyte subsets in sheep hemal nodes

Abstract

Marked differences were found in the percentage and distribution of lymphocyte subsets (CD5, CD4, CD8, T19, CD45, and CD45R cells) in hemal nodes compared to those in mesenteric lymph nodes and blood. There were a greater number of T19 (gamma/delta)+ lymphocytes and fewer CD8+ lymphocytes in hemal nodes than in mesenteric nodes and a higher percentage of CD4+ in hemal and mesenteric lymph nodes than in blood. T19 (gamma/delta)+ lymphocytes were found throughout hemal nodes but were absent from the follicles. Of special interest was the finding that 20% of hemal node lymphocytes appeared not to express CD45 (leucocyte common antigen). According to these results, because of the unique distribution of lymphocyte subsets and the presence of germinal centers, hemal nodes may have a specialized role in the immune system.