A mechanism for selective lymphocyte homing in bovine hemal nodes

The distribution and abundance of MECA-79+ cells in bovine hemal nodes (HNs) was analyzed. In addition, T cell subsets which expressed the homing receptor l-selectin were analyzed by flow cytometry. The frequency of MECA-79+ HNs varied depending on the location. There were 61, 33, and 17% MECA-79+ HN in the subcutaneous region, along the abdominal aorta and in the mesenteric region, respectively. MECA-79+ cells in mesenteric lymph nodes were mainly distributed in the paracortex. Many MECA-79+ cells were distributed in the perifollicular area of HNs and a few positive cells were also located in the paracortical and interfollicular areas. CD4+ and CD8+ l-selectin+ cells were significantly higher in MECA-79+ HNs compared to MECA-79− HNs. The data suggest that a selective lymphocyte homing mechanism exists in bovine HNs, which could be related to functional differences between locations.