Lymphocytes bearing single or double surface immunoglobulins in umbilical cord blood.

ABSTRACT

Lymphocytes from the umbilical cord blood of 20 newborn infants and the peripheral blood of 18 adult volunteers, were studied for surface-stable immunoglobulins by the direct immunofluorescence technique. Goat antiserums to human light and heavy chains were used. Cord blood yielded a significantly higher percentage of lymphocyte bearing mu + delta chains, and a lower percentage bearing only delta chains. The number of B cells bearing light chains (K + lambda) or heavy chains (mu + delta +(mu + delta) was higher in cord blood than in the adult peripheral blood. The high percentage of cells bearing double markers (probably virgin B-cells) and the low number of cells bearing only IgD, (probably the cells responsible for secondary antibody responses) could be explained by the inhibition of the IgM-to-IgG switch in the antibody production of newborns.