Lymphocyte subpopulations in the neonate: high percentage of circulating B73.1+, HNK-1- cells.

The reactivity of B73.1 monoclonal antibody was evaluated on unseparated and on T cell-depleted and T cell-enriched fractions of both cord blood lymphocytes (CBL) and adult peripheral blood lymphocytes (a-PBL). The reactivity of this monoclonal antibody with the E-, OKT3-, OKT8+, HNK-1- subset of CBL, previously demonstrated to have NK activity, was also studied. The data show that B73.1+ cells were present in similar percentages in CBL and a-PBL while HNK-1+ cells were very low in CBL. In addition the B73.1 monoclonal antibody reacted with about 50% of the E-, OKT3-, OKT8+, HNK-1- CBL and within this subset the majority of the B73.1+ cells were PNA-. These data support the hypothesis that part of this neonatal subpopulation, belongs to the NK cell lineage. Moreover the results obtained by double-labelling with B73.1 monoclonal antibody and PNA suggest that the E-, OKT3-, OKT8+, HNK-1- CBL include either different subsets or various differentiation stages of the same subset.