Evidence for a spontaneous activity and a weak helper function in cord blood lymphocytes

Human lymphocytes from cord blood (CBL) and adult peripheral blood were studied for suppressive and stimulatory effects. Using a double chamber assay we found that via soluble substance(s) cells from approximately 90% of all cord bloods and about 25% of the tested adults could diminish the proliferative response and the IgM and IgG plaque-forming cell numbers of phytohemagglutinin (PHA) stimulated adult cell cultures. CBL were spontaneously suppressive, whereas cells from 'suppressive adults' required activation with PHA to exert suppression. Co-cultures of T cells and B cells were stimulated with pokeweed mitogen. Cord B lymphocytes were able to secrete not only IgM but also IgG. The Ig response of CBL was weaker than that of adult cells, which argues for an immaturity of cord helper T lymphocytes, and possibly also of cord B lymphocytes.