Résumé
1. Normal and schistosome-infected mice were similar in terms of the total number of bone marrow myeloide cell precursors and their proliferative capacity in vitro when stimulated with supernatants ofL-929 cells containing M-CSF. 2. Delayed differentiation of bone marrow m=neutrophil granulocytes and blood monocytosis of infected animals were consistent with a modification in the differentiation of bone marrow myeloid precursors, favoring the production of a mono-macrophage cell lineage. 3. Macrophages isolated from periovular franulomas secreted a considerable stimulatory activity for the proliferation of the mono-macrophagic cell lineage, whereas peritoneal macrophages from the same animals had only a very low stimulatory activity. 4. We conclude that systemic hyperplasia of mono-macrophagic cells in schistomiasis may be relatted to their increased release from the bone marrow and to their peripheral amplification in inflammatory tissue infiltrate as consequence of the local production of stimulatory activity for their proliferation