ABSTRACT
This chapter summarizes the hemopoietic and survival-enhancing effects of numerous immunomodulators evaluated in our radiation models, describes multiple mechanisms through which immunomodulators mediate their protective and therapeutic effects in irradiated animals based on in-depth studies performed with the immunomodulator glucan. It examines the ability of numerous hemopoietic cytokines to accelerate hemopoietic recovery therapeutically following radiation-induced aplasia. The effects of cytokines in large-animal radiation models are perhaps even more relevant to their clinical potential. Hemopoietic and immune depression is well-documented phenomena following chemotherapy and/or radiotherapy. Endotoxin was the first immunomodulator demonstrated to enhance survival when administered prior to radiation exposure and, thus, to function as a “radioprotector”. Several immunomodulators and cytokines can also enhance survival even when administered after radiation exposure. Once radiation exposure has occurred and the hemopoietic system has been injured, hemopoietic regeneration is limited by the number of surviving stem and progenitor cells.
