Studies of human lymphocytes in the newborn and the aged

Abstract

Proportions and absolute numbers of T and B lymphocytes were determined among 30 newborn infants and a group of 77 elderly patients 60 to 95 years of age. Total lymphocytes in the cord blood of the newborn showed a distinct elevation in total numbers of T and B lymphocytes (p < 0.005) as compared to that in blood from normal adult controls, reflecting the relative lymphocytosis of infancy. Proportions of cord blood T lymphocytes as reflected by the sheep cell rosette technic were considerably lower than those in lymphocytes from normal adult controls, however, proportions of cord blood T lymphocytes as determined by indirect immunofluorescence were not significantly different from those in controls. Old people showed a significant reduction in total numbers of lymphocytes (p < 0.005) when compared with those in normal adult controls 18 to 51 years of age. Moreover, there was a significant increase in the relative proportions of peripheral blood B lymphocytes in the elderly although the absolute numbers of B cells did not differ from those in younger controls. A significant decrease in total numbers of T cells as measured both by sheep cell rosettes and indirect immunofluorescence was recorded among older patients (p < 0.001). In addition, there was a broad increment in the incidence of various autoantibodies (antinuclear, anti-IgG, antismooth muscle, antimitochondrial and antiparietal cell) among the old people studied. No direct correlation could be determined between relative B-cell percentage increase or T-cell decrease and the presence of various autoantibodies in individual patients. Diminution in total lymphocyte counts as well as absolute numbers of T cells in the elderly may provide the cellular basis for an increased susceptibility to neoplasia and infection.