title: High T cell colony numbers do not reflect immune competence.
abstract: The number of T cell colonies growing from ficoll separated PHA-stimulated peripheral blood cells was compared to 3H-thymidine uptake in 133 normal donors of all ages. Unexpectedly, the two parameters did not correlate: The tendency of growing cells to aggregate during the incubation period resulted in few, but large spherical colonies in persons who by young age and high counts for thymidine uptake were judged to have good T cell function. This clustering effect was less pronounced in old persons and those with a low PHA response; it was virtually absent in 17 of 18 patients with undoubted cellular immune deficiency early after allogeneic bone marrow transplantation. This resulted in a growth pattern consisting of a high number of small scattered colonies. The capacity of growing cells to aggregate was sensitive to sublethal irradiation. We conclude that the number of T cell colonies growing from a given cell suspension not only depends on the number of lymphocytes responding to the mitogen. It is negatively determined by the drive of growing cells to cluster. This phenomenon deserves further study, since it appears to be a parameter of cellular immune competence which is not readily recognized with 3H thymidine incorporation.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D016026:Bone Marrow Transplantation; D002449:Cell Aggregation; D002454:Cell Differentiation; D002648:Child; D002675:Child, Preschool; D003114:Colony-Forming Units Assay; D005260:Female; D006801:Humans; D007121:Immunocompetence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010835:Phytohemagglutinins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000166:cytology*
chemical_list: D010835:Phytohemagglutinins