Peripheral blood lymphocytes are heterogeneous and can be divided into subpopulations based on cell surface markers. Lymphocytes from 101 normal individuals of all ages were tested for their ability to form spontaneous rosettes with sheep erythrocytes (T cells) and for surface immunoglobulins (B cells). Cord bloods of newborn infants and bloods from children (age 1–10 years) showed greater numbers of total lymphocytes, total T cells and unmarked cells than a control group of 50 individuals from age 11–60 years. In 22 normal elderly individuals (age 61–98 years), total lymphocytes and total T and B cells were not decreased. These data suggest that the depression of cellular immune response described in elderly populations may be related to a dysfunction in a segment of T cells or an aberration in the complex interaction among T cells, B cells and macrophages.

SUMMARY Rosetting and non-rosetting lymphocytes collected from normal individuals were stained for the presence of beta-glucuronidase, periodic-acid Schiff activity, gamma glutamyl transpeptidase, acid phosphatase, and alpha-naphthyl butyrate esterase. Lymphocytes which formed rosettes with sheep erythrocytes and non-rosette forming lymphocytes contained cytochemical reaction products for all five stains. Beta-glucuronidase (p < 002) and acid phosphatase (p < 001) were more frequently found in rosette forming lymphocytes. However, non-rosetting cells were more frequently periodic-acid Schiff positive (p < 0001). Gamma-glutamyl transpeptidase and alpha-naphthyl butyrate esterase were present equally in rosette and non-rosette forming lymphocytes. In addition, 33 non-Hodgkin's lymphomas were studied for cell surface markers and cytochemical reactions. In 17 of 19 B cell lymphomas, there was a paucity of lymphocytes containing beta-glucuronidase. However, in three of four T cell proliferations, there were numerous lymphoid cells positive for beta-glucuronidase. The periodic-acid Schiff and acid phosphatase reactions varied greatly within B, T, and null cell lymphomas and thus were of little diagnostic value in determining the cell of origin of these neoplastic lymphoid cells.