Lymphocyte subpopulations in the neonate: A subset of HNK-1 −, OKT3 −, OKT8 + lymphocytes displays natural killer activity

It has been recently reported that cord blood lymphocytes (CBL) contain a subpopulation of OKT8 +, sheep erythrocyte-rosetting negative (E −) cells not detectable in adult peripheral blood lymphocytes (a-PBL). The present studies were undertaken to characterize this subset of lymphocytes functionally and phenotypically. OKT8 + cells were purified from E-depleted CBL by negative selection on nylon-wool columns as well as by positive selection on plates coated with rabbit antibody to murine IgG (panning). The purified CBL displayed natural killer (NK) activity against K562 erythroleukemic cells. Although most of these CBL were large granular lymphocytes, they lacked typical NK markers such as HNK-1 and OKM1 surface antigens. Most OKT8 +, OKT3 − cells were also OKT10 +, Ia + and had the receptor for peanut agglutinin. These CBL may represent a stage along the differentiation pathway leading to mature NK or T cells.