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[Granulopoietic inhibitor]
1Third Department of Internal Medicine, Kinki University School of Medicine, Osaka.
The differentiation and proliferation of granulocytes are specifically supported by G-CSF. On the other hand, little is known about the negative modulation of granulopoiesis. We had found that the sera obtained from patients during the recovery phase of hematopoiesis after chemotherapy inhibited the formation of CFU-G, suggesting the modulation of granulopoiesis by negative regulator(s). As the inhibitory effect was specific for CFU-G, the inhibitor in this inhibitory sera was suggested the soluble G-CSF receptor. Several G-CSF receptor fragments were detected in the concentrated fractionated-urine by the immunoblot analysis using the specific antibody against the cytokine receptor homologous (CRH) domain of G-CSF receptor. G-CSF binding protein was successfully obtained from normal human plasma by G-CSF affinity column. Major component was the 90Kd of protein which was thought to be the extracellular domain of G-CSF receptor by the immunoblot analysis. About 90Kd- and 30Kd- bands of the binding-complex formation between G-CSF monomer and the extracellular domain or the fragment of G-CSF receptor were shown in the immunoblot analysis using anti-G-CSF Ab. CFU-G formation was suppressed by the solution of soluble G-CSF receptor fragments, suggesting the competition of G-CSF which bind to granulocyte precursor cells.
The differentiation and proliferation of granulocytes are specifically supported by G-CSF. On the other hand, little is known about the negative modulation of granulopoiesis. We had found that the sera obtained from patients during the recovery phase of hematopoiesis after chemotherapy inhibited the formation of CFU-G, suggesting the modulation of granulopoiesis by negative regulator(s). As the inhibitory effect was specific for CFU-G, the inhibitor in this inhibitory sera was suggested the soluble G-CSF receptor. Several G-CSF receptor fragments were detected in the concentrated fractionated-urine by the immunoblot analysis using the specific antibody against the cytokine receptor homologous (CRH) domain of G-CSF receptor. G-CSF binding protein was successfully obtained from normal human plasma by G-CSF affinity column. Major component was the 90Kd of protein which was thought to be the extracellular domain of G-CSF receptor by the immunoblot analysis. About 90Kd- and 30Kd- bands of the binding-complex formation between G-CSF monomer and the extracellular domain or the fragment of G-CSF receptor were shown in the immunoblot analysis using anti-G-CSF Ab. CFU-G formation was suppressed by the solution of soluble G-CSF receptor fragments, suggesting the competition of G-CSF which bind to granulocyte precursor cells.