REDUCED EXPRESSION OF THE INTERLEUKIN-2-RECEPTOR GAMMA-CHAIN ON CORD-BLOOD LYMPHOCYTES - RELATIONSHIP TO FUNCTIONAL IMMATURITY OF THE NEONATAL IMMUNE-RESPONSE

Mutation of the interleukin-2 (IL-2) receptor gamma chain, which also serves as a component of the receptor complexes for IL-4, 7, 9 and 15, results in severe immune deficiency. We hypothesized that the immunol ogical immaturity of healthy neonates might be associated with low lev els of expression of this receptor molecule. Using monoclonal antibody and a highly sensitive immunofluorescence method, we showed that IL-2 receptor gamma chain is expressed at significantly lower levels on co rd blood cells compared with adult cells. IL-2-dependent T-cell activa tion in vitro was reduced in cord blood cells compared with adult cell s, but B-cell responses to IL-4 were not obviously impaired. The lower level of expression of the gamma chain and some other cytokine recept or chains may contribute to the immunological immaturity of the newbor n, by selectively depressing particular immunological mechanisms.