LYMPHOCYTE DEPLETION DURING TREATMENT WITH INTENSIVE CHEMOTHERAPY FORCANCER

Recently we have observed an increased incidence of opportunistic infe ctions in patients treated with intensive chemotherapy for cancer. Bec ause T-cell depletion is associated with similar clinical events in hu man immunodeficiency virus infection and after bone marrow transplanta tion, we have analyzed peripheral blood lymphocyte populations in a se ries of patients during treatment with intensive chemotherapy for canc er. Although neutrophil, monocyte, and platelet numbers consistently r ecovered to greater than 50% of pretreatment values after each sequent ial cycle of therapy, lymphocyte numbers did not recover within the sa me time period. B cells decreased rapidly from a mean value of 149 +/- 46/mm(3) before chemotherapy to 4 +/- 1/mm(3) during chemotherapy (P =.01). CD4(+) T cells decreased from a mean of 588 +/- 76/mm(3) before chemotherapy to 105 +/- 28/mm(3) during chemotherapy (P =.0002) and C D8(+) T cells decreased from a mean of 382 +/- 41/mm(3) before chemoth erapy to 150 +/- 46/mm(3) during chemotherapy (P =.0009). Natural kill er cell numbers did not show significant declines (171 +/- 30/ mm(3) b efore, 114 +/- 24/mm(3) during, P =.19). Based on the history of oppor tunistic complications in patients with other disorders who display si milar degrees of CD4(+) T-cell lymphopenia and preliminary observation s in this population, immune incompetence could surface as a dose-limi ting toxicity for highly dose-intensive chemotherapy regimens.