[Tissue-specific inhibitor and stimulant of monocytopoiesis (monocytic chalone and antichalone)]

Fractions inhibiting and stimulating 3H-thymidine inclusion into mouse bone marrow monocyte precursors were detected in human and cattle monocytes and blood plasma. Species-non-specificity, tissue specificity, thermolability, typical dose-reaction dependence, mutual neutralization permitted the authors to suggest that these fractions are monocytic chalones and antichalones.