A granulopoiesis inhibitor partially purified from large-scale serum-free cultures of porcine leukocytes.

A method is described for the partial purification of a granulomonopoiesis inhibitor derived from 200 l-batches equivalent to 1 kg or 2 X 10(12) leukocytes of porcine blood. Serum-free conditioned media were concentrated and separated via ammonium sulfate precipitation, acetone partitioning, ultrafiltration and gel chromatography. The active substance revealed a molecular mass of 500-700 Da and was not thiol-dependent, thus contrasting it with previously-reported granulopoiesis inhibitors. Inhibition of colony formation in an in vitro myeloid stem cell assay using various colony-stimulating factors showed that mature granulocytes and monocytes were equally affected. Apparent lack of cytotoxicity was suggested using a new reversibility test.