893 MORPHOLOGY, DEVELOPMENT AND DISTRIBUTION OF HUMAN NK CELLS IDENTIFIED BY A MONOCLONAL ANTIBODY (HNK-1)

Abstract

A monoclonal IgM antibody (HNK-1) has been shown to react with a subset of human lymphocytes that can function as natural killer (NK) and antibody dependent killer (K) cells. HNK-1 antigen is present on 60% of Tγ cells (Fcγ receptor+, E-rosette+) and 56% of “null” cells (FcγR+ER−sIg-) but not on sIg-bearing B cells and monocytes. In the present studies we have used immunofluorescent and cell sorter techniques to examine the development, distribution, morphology and function of cells expressing HNK-1. Fewer than 1% of cells in thymus and newborn blood samples were HNK-1+. The number of circulating HNK-1+ cells increased as a function of age: <5% of blood mononuclear cells in children under 15, 5-35% in adults 15 to 40 and 25-45% in adults >40 years of age. HNK-1+ cells comprised a mean of 12% of spleen cells but <1% of lymph node cells. The level of NK and K cell functions was closely related with the numbers of HNK-1+ cells in all tissues examined. Morphologically, HNK-1+ cells were defined as a homogeneous population of lymphocytes with abundant cytoplasm containing azurophilic granules. A significant proportion of HNK-1+ cells coexpressed antigens previously defined by monoclonal antibodies on T cells and monocytes. Our studies define a morphologically distinct subpopulation of lymphocytes of unknown origin with NK and K activities, the HNK-1+ cells were shown to expand as a function of age and exhibit selective migration. NIH CA 16673 and CA 27197.