Deficient Quantitative Expression of CD45 Isoforms on CD4+ and CD8+ T Cell Subpopulations and Subsets of CD45RA<sup>low</sup>CD45RO<sup>low</sup> T Cells in Newborn Blood

Abstract

Deficiencies in the quantitative expression of CD45RA and CD45RO on CD4+ and CD8+ T cells and in a population of CD45RA(low)CD45RO(low) T cells in blood from term newborn infants were found by flow cytometry. The relative frequencies of CD45RO on CD4+ T cells from adults and newborn 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 newborn T cells was significantly less than that found on adult blood T cells.