Signaling substances in bone marrow interstitial fluid (BMIF) in leukemia. (A) Growth of normal bone marrow progenitor cells (CD34 cells) added BMIF from patients with acute myeloid leukemia (AML) before and after induction chemotherapy. A marked increase in colony numbers (*P < 0.05) was noted upon this initial treatment in 7 of 10 patients with AML entering complete remission. BMIF from the remaining three AML patients that only entered partial remission yielded similar colony numbers before and after induction chemotherapy. Colony formation in the presence of normal BMIF is shown for comparison. (B) Tumor necrosis factor (TNF)-α concentrations in plasma and BMIF before and after induction chemotherapy in 7 of 10 patients with AML entering complete remission. This treatment resulted in a substantial fall in TNF-α concentration (*P < 0.05) in the BMIF, but not in plasma. Normal plasma and BMIF values are shown for comparison. Individual values are shown. Horizontal lines refer to means. Modified from .