ERYTHROID COLONY STIMULATING AND INHIBITING CELLS IN PERIPHERAL-BLOOD OF TRANSFUSED DOGS - SEPARATION OF FUNCTION BY VELOCITY SEDIMENTATION

Abstract

Addition of normal dog peripheral blood lymphocytes (PBL) to allogeneic marrow cultures increases number of marrow-derived erythroid colonies (EC), but PBL from transfused dogs usually inhibited EC growth from marrow of the transfusion donor. Cells in normal dog PBL responsible for stimulating EC growth sedimented in a narrow peak at 4.30 mm/h. A similar stimulating cell population existed in transfused dogs and could be separated, on the basis of size, from cells inhibiting EC growth. EC-stimulating cells from transfused dog PBL sedimented at 3.3-5.0 mm/h, while cells responsible for inhibition were larger and sedimented more rapidly at 5.4-8.1 mm/h. Cells capable of stimulating allogeneic EC were present in transfused dogs, but their stimulating ability was masked by presence of EC-inhibiting cells. Coculture experiments designed to test lymphocyte/marrow cell interactions may miss significant but opposing effects if unfractionated cells are used.