Platelet support and the use of cytokines.

Severe thrombocytopenia and clinical bleeding remain major clinical problems in leukemic patients undergoing remission induction and those receiving high dose chemotherapy. Prophylactic platelet transfusions have made a major impact on hemorrhagic deaths over the last 20 years. The effectiveness of platelet transfusions is influenced by a number of clinical factors including the status of the spleen, prior bone marrow transplantation, the presence of disseminated intravascular coagulation and the presence of HLA antibodies. Optimal platelet transfusion therapy requires that transfusions be monitored routinely by post-transfusion counts and that a refractory group be clearly defined. The cytokine granulocyte colony stimulating factor (G-CSF) has not had a clinically significant impact on thrombocytopenia. Granulocyte-macrophage colony stimulating factor (GM-CSF) also probably has little clinical relevance, although in a randomized study, thrombocytopenia was worse in GM-CSF-treated patients. Interleukin-3 (IL-3) can increase platelet count and has the potential to protect against thrombocytopenia in patients receiving chemotherapy. This hypothesis is currently being tested in on-going clinical trials.