Functional subsets of peripheral blood mononuclear cells in transfused dogs separated by size with the fluorescence activated cell sorter

We studied the capability of the fluorescence activated cell sorter (FACS II) to separate, by size, functional subsets of peripheral blood mononuclear cells (PBMC) in normal and transfusion sensitized dogs. PBMC were analyzed for their effect on erythroid colony (EC) growth from marrow of the transfusion donor or unrelated dog. Data indicate that 1) in normal dogs a population of small PBMC which stimulate EC growth could be separated from larger PBMC which had no significant effect on EC, 2) in transfused dogs small PBMC also stimulated EC growth but the large PBMC significantly inhibited EC, and 3) following transfusion-induced sensitization there was an increased number of large PBMC in peripheral blood.