Changes in the bone marrow of cancer patients treated with recombinant interferon alpha-2.

Bone marrow aspirates and biopsy specimens in 12 patients with solid tumors treated with recombinant interferon alpha-2, 3 to 100 X 10(6) units per day, were evaluated in a blinded fashion both before and after therapy. No change in overall cellularity was noted. There was significant accumulation of lymphocytes (3.9 +/- 1 versus 10 +/- 2.7, p = 0.036), decrease in eosinophils (4.5 +/- 0.8 versus 2.2 +/- 0.7, p = 0.011), and decrease in red cell precursors (36.4 +/- 3.1 versus 28 +/- 4.2, p = 0.091). A trend to accumulation of white cell precursors, metamyelocytes (8.8 +/- 1.4 versus 12 +/- 2.0, p = NS), and band forms (10.0 +/- 1 versus 12.1 +/- 1.2, p = NS) was noted. No megaloblastosis, ring sideroblasts, or block in differentiation was observed. These observations are most consistent with reversible block in release of cells from the bone marrow.