NEONATAL LYMPHOCYTE REACTIVITY AS AN INDICATOR OF INTRAUTERINE BACTERIAL CONTACT

Abstract

The in-vitro response of neonatal lymphocytes to a microorganism was studied to determine whether it would serve as an indicator of intrauterine fœtal-antigen contact in infants born of mothers whose pregnancies were complicated by urinary-tract infection. The experimental model consisted of harvesting peripheral-blood lymphocytes from neonates born to two groups of mothers: those who were known to have had significant Escherichia coli bacteriuria or pyelonephritis at some time during gestation; and those who, on one occasion at least, had normal urine cultures, and were without documented disease of the urinary tract. The lymphocytes were grown in cell culture with autologous plasma and in the presence of a cell-free extract of E. colias the stimulating antigen. On the fourth day, mitotic arrest was produced by colchicine, the cultures were harvested by centrifugation of the cellular sediments, and coverslips were treated with Wright's stain. Mitoses, estimated quantitatively, were considered the experimental endpoint and an indicator of an anamnestic immune response. Immunoglobulins (IgA and IgM) were measured by radial immunodiffusion. Significant mito- genesis was observed in all 10 cultures containing lympho- cytes from neonates born of mothers with bacilluria. These infants had a considerable degree of neonatal morbidity. In contrast, 9 out of 11 cultures containing lymphocytes from the second group of neonates, who had no birth complication, were non-reactive to the identical in-vitro antigen. Immunoglobulin levels generally were not raised in either experimental category and did not correlate with the mitogenic response. The results are consistent with the concept that maternal infection may result in tranplacental transfer of bacteria with adverse clinical consequences, and provide evidence that cellular reactivity, rather than humoral antibody, more directly reflects the antigenic exposure of the fŒtus.