Circulating lymphocyte populations in Hodgkin's disease after mantle and paraaortic irradiation.

The effect of mantle and paraaortic radiation on peripheral blood lymphocytes was studied in 11 previously untreated patients with early stage Hodgkin's disease using a series of monoclonal antibodies defining immunoregulatory lymphoid cells. Immediately following the completion of radiotherapy, there was a significant reduction in the number of lymphocytes and the percent of circulating T cells. This acute decrease in T cells was due to a marked diminution in the number of inducer T cells, while the fraction of suppressor T cells remained constant. These changes persisted for up to 12 mo and were accompanied by a later increase in the fraction of circulating B lymphocytes and cells bearing surface Ia. It thus appears that mantle and paraaortic radiotherapy causes a relatively selective reduction in the inducer T-cell population. The implications of a change in the ratio of inducer to suppressor T cells is discussed.