Peripheral blood T and B lymphocytes in men in different age groups.

Peripheral blood T and B lymphocytes were determined in normal humans at different ages. Spontaneous rosette formation with sheep red blood cells (SRBC) was used as a marker for T cells. B cells were detected by immunofluorescent staining of membrane-bound immunoglobulins. Blood samples from old individuals contained significantly lower T lymphocyte numbers than those from children. This diminution of circulating T cells caused a reduction of the total lymphocyte count in the elderly persons. No significant differences were between the T cell values of young and old adults. Whereas the percentages of B cells indicated an increase of this lymphocyte population in old humans, the absolute numbers of B lymphocytes remained almost unchanged during aging.