BACKGROUND AND OBJECTIVE: Tumor necrosis factor-a plays an important role in hematopoiesis. Its effects are mediated through two membrane-bound receptors: TNF-R I (p55; CD 120a) and TNF-R II (p75; CD 120b). The aim of our study was to investigate the relative roles of these receptors. DESIGN AND METHODS: We analyzed in 16 acute myeloid leukemia cases whether TNF-alpha could induce in vitro maturation and apoptosis. We then investigated which of the two receptors was provoking monocytic maturation and which was responsible for apoptosis by using the agonistic MoAb HTR-9, directed at CD120a, and the CD120b antagonistic MoAb UTR-1. RESULTS: Monocytic maturation (morphologic and immunologic) was induced in all cases studied, although to different rates, by TNF-alpha and by HTR-9 incubation. The addition of UTR-1 to TNF-alpha did not abolish maturation, nor did it affect apoptosis, which was present in primary AML cultures after 4 and 10 days. INTERPRETATION AND CONCLUSIONS: We present here evidence that the sole stimulation of CD 120a, but not of CD120b, by TNF-alpha is responsible for bot monocytic maturation and apoptosis of primary AML blasts.
BACKGROUND AND OBJECTIVE: Tumor necrosis factor-a plays an important role in hematopoiesis. Its effects are mediated through two membrane-bound receptors: TNF-R I (p55; CD 120a) and TNF-R II (p75; CD 120b). The aim of our study was to investigate the relative roles of these receptors. DESIGN AND METHODS: We analyzed in 16 acute myeloid leukemia cases whether TNF-alpha could induce in vitro maturation and apoptosis. We then investigated which of the two receptors was provoking monocytic maturation and which was responsible for apoptosis by using the agonistic MoAb HTR-9, directed at CD120a, and the CD120b antagonistic MoAb UTR-1. RESULTS: Monocytic maturation (morphologic and immunologic) was induced in all cases studied, although to different rates, by TNF-alpha and by HTR-9 incubation. The addition of UTR-1 to TNF-alpha did not abolish maturation, nor did it affect apoptosis, which was present in primary AML cultures after 4 and 10 days. INTERPRETATION AND CONCLUSIONS: We present here evidence that the sole stimulation of CD 120a, but not of CD120b, by TNF-alpha is responsible for bot monocytic maturation and apoptosis of primary AML blasts.