160 FUNCTIONAL CHARACTERIZATION OF ECTO-5|[prime]|-NUCLEOTIDASE (ECTO-5|[prime]|-NT) POSITIVE AND NEGATIVE HUMAN LYMPHOCYTES

摘要

Human T and B lymphocytes, separated into ecto-5′-NT positive and negative populations with goat antl-5′-NT antibodies and the fluorescence-activated cell sorter, were characterized in functional assays. Ecto-5′-NT? T cells proliferated as well as, or better than, ecto-5′-NT+ T cells after stimulation with phytohemagglutinin or in a mixed lymphocyte reaction. Ecto-5′-NT? T cells also provided more help for pokeweed mitogen (PWM)-stimulated immunoglobulin synthesis than ecto-5′-NT+ T cells. Therefore, the inability of ecto-5′-NT deficient lymphocytes from patients with immunodeficiency diseases to respond in these assays cannot be attributed solely to their reduced ecto-5′-NT activity. In contrast, ecto-5′-NT+ T cells proliferated in response to ten-fold lower doses of phorbol esters than ecto-5′-NT+ T cells, suggesting that ecto-5′-NT+ T cells may utilize unique biochemical pathways of cellular activation or may have a preferential ability to respond to certain stimuli.Ecto-5′-NT positive and negative B cells were tested for the ability to synthesize IgM and IgG after stimulation with PWM and Epstein Barr virus. Although both groups of cells synthesized IgM, the synthesis of IgG was restricted to the ecto-5′-NT+ sub-population. These data provide the first direct evidence that ecto-5′-NT is a marker for the functional maturation of human B cells and demonstrate that ecto-5′-NT is different from other human B cell surface antigens such as IgD, Leu 8, and HB-4 which are lost as B cells mature.