Explain Inhibitory Factors

Haemopoiesis may be inhibited by a decrease in the live1 of stimulatory growth factors. Generally there is a competition. No particular substance can actively inhibit this process. But now it is known that tissue specific locally produced inhibitor of cell proliferation are chalones. A granulocytic chalone is produced by mature / immature granulocyte. It inhibits DNA synthesis granulocyte precursor cells, thereby, decreasing the number of mitosis and cell differentiation. They have specific factor to inhibit haemopoesis wherein neutrophil level increases. Some other inhibitory factors are small peptides "Fe" string proteins etc. They are not cytotoxic generally.