The lymphocyte transformation response of 17 chronic lymphocytic leukemia patients when tested in the short-term tissue culture with PHA-M, and PPD was found to be significantly decreased when compared to normal subjects. Serum factors were not found to be responsible for this cellular hyporesponsiveness. The proportions of immunoresponsive lymphocytes found in the patients’ peripheral circulation decreased as their white blood cell count increased. The transformation response to PHA-M was generally better than to PPD. Neither the PPD negative patients nor the normal PPD negative subjects’ cells responded to PPD stimulation in vitro.
Monocytes usually would phagocytize particles added to the cultures and could thus be distinguished from the nonphagocytic proliferating lymphocytes which were the only cells that incorporated thymidine H3. Radioautographs of tritiated thymidine also revealed the rate of PPD lymphocyte transformation to be slower than with PHA-M. There were no significant differences in the proportions or the degree of leukemic and normal transformed lymphocyte labeling with tritiated thymidine.
Cytogenetic studies revealed that the patients’ mitotic indices both in vivo and in vitro were markedly depressed. The modal chromosome number was 46 in each patient, and no cytogenetic abnormalities other than those due to exposure to radiation were found.