Differences in the formation of normal T lymphocyte colonies by peripheral blood cells from patients with chronic lymphocytic leukaemia and Hodgkin's disease

Lymphocytes isolated from the peripheral blood of normal persons, patients with untreated B cell chronic lymphocytic leukemia (CLL), active untreated Hodgkin's disease and Hodgkin's disease in remission, were studied for their ability to form T lymphocyte colonies in vitro in semi-solid agar. The frequency of colony formation was tested after induction with phytohemagglutinin (PHA), in the presence or absence of added conditioned medium (CM) from PHA stimulated normal human lymphocytes. This CM contained the normal T cell colony inducing protein TCI. In the absence of added CM, the seeding of 5 × 105 cells per 35 mm petri dish from normal persons gave a mean of about 1700 colonies per petri dish, whereas at this seeding level lymphocytes from CLL patients, which contained a lower percentage of T lymphocytes, gave no colonies. Increasing the number of cells seeded from the CLL patients resulted in the formation of T cell colonies and at a seeding level with a similar number of cells with E rosettes, lymphocytes from normal persons and CLL patients gave similar frequencies of T cell colony formation. The addition of normal CM increased the number of colonies by 2·5 fold with cells from normal persons and 1·6 fold with cells from the CLL patients. Six out of nine patients with active Hodgkin's disease and five out of nine patients with Hodgkin's disease in remission for 18–84 months, gave only 0–150 colonies per petri dish compared to the normal mean of 1700. In many of these cases, the number of colonies remained unchanged, or did not rise above about 300, even after adding normal CM. These results indicate, that T lymphocytes from normal persons and CLL patients appear to have similar colony forming ability when a similar number of T lymphocytes are seeded; and that there are patients with Hodgkin's disease in an active form or in remission, which have a defect in T lymphocyte colony formation which was not repaired by adding the T cell colony inducing activity in CM from PHA stimulated normal lymphocytes. The study of in vitro colony formation should be a useful assay for further elucidation of the changes in the control of T lymphocyte proliferation that can occur in various diseases.