Cord blood lymphocyte subpopulations and mitogenic activity in whole blood microculture

Comparative studies on cord and adult blood showed that cord blood contained at least twice as many lymphocytes as adult blood. Relatively, the percentage of T cells (E-RFC) was significantly lower in cord blood lymphocytes. The percentage of B cells (EAC-RFC and SmIg bearing cells), as well as the total number of T and B cells (mm(-3)), was significantly higher in cord blood. In vitro mitogen transformation of cord and adult lymphocytes in while blood, cultured for different times and diluted to contain equivalent numbers of lymphocytes per culture, showed significant qualitative and quantitative differences. Responses to the T cell mitogens phytohaemagglutinin (PHA) and concanavalin A (Con A) were examined from 3 to 6 days in culture. Cord blood lymphocytes were significantly more responsive when cultured for 3 to 4 days, similar to adult cells after 5 days, but significantly less responsive after 6 days in culture. The optimal levels of T cell mitogen responsiveness in cord cells (Day 4) were similar to adut cells (Day 6). Spontaneous transformation of unstimulated lymphocytes and B cell mitogen transformation with pokeweed mitogen (PWM) and staphylococcal protein A (SpA) were all significantly higher in cord blood than in adult whole blood cultured for 5 days.