[Cytokines and malignant hemopathies: leukemias and bone marrow graft]

Cytokines are now part of the modern armentarium utilized against malignant blood diseases. The essentially lymphocytic haematopoietic growth factors (G-CSF, GM-CSF, IL-3) reduce the infectious morbidity associated with the deep and prolonged neuropoenia induced by the myelo-ablative conditioning for autologous or allogeneic bone marrow transplantations, and widening their indications is tempting. The reluctance expressed about their use in chemotherapy of acute myeloid leukaemia is abating now that controlled studies have shown that they preserve the complete response rate and shorten the duration of leucopoenia. Moreover, they modify the leukaemia biological response, which makes it possible to increase the cytotoxicity of certain drugs and constitutes a new approach to drug-resistant leukaemias. Immuno-modulating cytokines (interferon alpha, interferon gamma, interleukin-2) act through mechanisms that are still ill-defined: antitumoral activity, modification of biological responses, immunoactivation. Nevertheless, interferon alpha has revolutionized the treatment of hairy cell leukaemia and myeloid leukaemia, with a 70% remission rate. The scarcity of complete responses (10% of hairy cell leukaemias) or cytogenetic responses (20% of chronic myeloid leukaemias) justifies a combined treatment (chemotherapy+immunotherapy?) to improve these patients' cure rate. The anti-leukaemic activity of interleukin-2, observed in patients with refractory relapses, produces 33% of responses, including 10% of complete responses, and it is tempting to test the impact of this immunotherapy on the control of residual leukaemia as adjuvant of complete remission using randomized trials.