DEFICIENT QUANTITATIVE EXPRESSION OF CD45 ISOFORMS ON CD4-CELL SUBPOPULATIONS AND SUBSETS OF CD45RA(LOW)CD45RO(LOW) T-CELLS IN NEWBORN BLOOD( AND CD8+ T)

Deficiencies in the quantitative expression of CD45RA and CD45RO on CD 4+ and CD8+ T cells and in a population of CD45RA(low)CD45RO(low) T ce lls in blood from term newborn infants were found by flow cytometry. T he relative frequencies of CD45RO on CD4+ T cells from adults and newb orn infants were 72 and 58%, respectively. However, in newborn infants greater than 70% of T cells expressing CD45RO also expressed CD45RA. In addition, the quantitative expression of CD45RA and CD45RO on newbo rn T cells was significantly less than that found on adult blood T cel ls.