Synthetic cytokines containing interleukin-3 exert potent megakaryopoietic activity

The shared properties of haematopoietic cytokines and their receptors have enabled the genetically engineered construction of several synthetic cytokines with increased haematopoietic activity and/or more desirable pharmacological characteristics. Thrombocytopenia remains a significant cause of morbidity in cancer patients undergoing allogeneic or autologous bone marrow/blood stem cell transplantation after myeloablative therapy including total body irradiation. Several in vitro, in vivo and preliminary clinical studies have demonstrated the efficacy of synthetic cytokines containing interleukin-3 in accelerating platelet recovery after radiotherapy-induced myelosuppression, enhancing G-CSF-mobilisation of CD34 positive cells for transplantation and increasing the ex-vivo expansion of myeloid and megakaryocytic progenitor cells. More randomised controlled clinical trials are needed to study the efficacy of the pre-transplant platelet mobilisation and the acceleration of the post-transplant platelet recovery. This also applies to cohort in vitro studies for expanding the production of CD41+ megakaryocytes from human bone marrow, mobilised peripheral blood and cord blood CD34 positive cells using myelopoietin as the only accepted synthetic cytokine containing interleukin-3.