Myeloprotective Effects of Interleukin-1 Following Exposure to Chemoradiotherapy
Interleukin-1 (IL-1), a cytokine with multiple immunological and inflammatory functions, has recently been demonstrated to play a role in hematopoietic regulation.1 Although IL-1 alone does not stimulate hematopoietic colony growth, it is synergistic with other growth factors and has been shown to be identical to hematopoietin-1.2 In addition to having a direct effect on early hematopoietic progenitors, IL-1 is capable of inducing production of various colony-stimulating factors (CSF’s) by accessory cell populations in the hematopoietic tissue.3 Administering IL-1 to mice pretreated with chemotherapy accelerated hematopoietic recovery and reduced the nadir in neutrophil count.4 Administering IL-1 to mice before or shortly after lethal irradiation protected them from severe neutropenia and subsequent death from septicemia.5,6 These results suggest that IL-1 induces a chain of events that probably affects the radiosensitivity of early hematopoietic progenitors.7 The effects of IL-1 on hematopoietic recovery after chemotherapy, together with IL-1’s radioprotective effect, indicate that this cytokine might have therapeutic potential when given either alone or in combination with other CSF’s in the treatment of chemoradiotherapy-induced myelosuppression. In contrast to stimulating blood-forming cells, IL-1 may induce endogenous production of hematopoietic inhibitors, including various prostaglandins, tumor necrosis factor alpha (TNFα), and interferon-gamma.8,9 Thus, the in vivo hematopoietic effects of IL-1 depend on the balance between its stimulatory and inhibitory activities.
KeywordsHematopoietic Progenitor Hematopoietic Growth Factor Neutrophil Recovery Radioprotective Effect Hematopoietic Recovery
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