Effects of chloramphenicol on hematopoietic inductive microenvironment.

Effects of chloramphenicol (CP) on hematopoietic inductive microenvironment (HIM) were studied using in vitro and in vivo assay systems. HIM was represented as fibroblast colonies (CFUF) in in vitro culture. CP suppressed the growth of not only granuloid committed progenitor cells (CFUC), but also CFUF in in vitro culture at the concentration of 10, 50 and 100 micrograms/ml. To analyze the function of HIM in vivo, the subcutaneous bone implantation method was used. The recovery of hematopoietic stem cells in subcutaneously implanted femora of mice, which were treated with a 500 mg/kg dose of CP daily for 6 days, was significantly decreased compared to the sham treated group. Suppressive effect of CP on HIM was shown. The important role of the derangement of HIM on the pathogenesis of CP-induced aplastic anemia was discussed.