Reduced lymphocyte colony formation with age.

The lymphocyte colony forming ability of 83 normal healthy individuals aged 17-89 was studied. The total lymphocyte count did not alter with age, but there was a decline in the colony forming ability of cells from people with increasing age (r = -0.68, P less than 0.001). This age related defect was further investigated in 11 mixing experiments using paired young and old individuals. It was found that the defect in aged individuals was due primarily to a defect in the number and/or proliferative ability of the colony forming cell.