In vitro Transformation of Cord Blood Lymphocytes by Antigens

Abstract

Newborn human lymphocytes respond vigorously to immunologically specific stimulation with homologous cells in mixed leukocyte cultures and to non-specific stimulants. Certain maternal infections can be transmitted to the human fetus and induce antibody production suggesting that the placental barrier is not impermeable to certain antigens. However, little is known about placental transfer of antigens in normal pregnancies. For this reason leukocyte culturews form radom cord blood samples were incubated with various antigens, and transformation was assayed by tritiated thymidine (TdR3H) uptake. Analysis of variance of the response of triplicate cultures revealed that a ratio of 3 : 1 or greater of uptake of TdR3H by stimulated to unstimulated cultures was borns tested that manifested such a significant (p < 0.01). The number of newborns tested that manifested such a significant in vitro response was 5/21 with streptolysin 0, 5/15 with Type I pneumococci, 4/17 with Group A type 12 streptococcal cell wall extract, 2/14 with E. coli, and 3/9 with S. enteritides endotoxin. Examinations of metaphases in cord blood cultures from male infants revealed that the could not have been due to the passage of maternal cells across the placenta. This 14–33% incidence of significant stimulation of cord blood lymphocytes by these common bacterial antigens is therefore either due to inborn cellular immunity or to transplacental transfer from the maternal circulation and prenatal sensitization of the fetus by these antigens. (Supported by : NIH Grant No. HD-04273.)