Studies on the recognition of xenogeneic cells by nonimmune macrophages. I. Destruction of chicken fibroblasts in vitro by murine macrophages.

Human cord blood lymphocytes were compared with adult lymphocytes with regard to proportions of cells with surface markers for surface immunoglobulin (Ig), receptors for C′3 and the Fc-portion of IgG, as well as two types of erythrocyte rosettes (rapid and late E-rosettes). A significant decrease (P < 0.02 ? 0.05) in both early and late E-rosettes was noted when cord cells were compared to adult lymphocytes. After 20 hr of incubation at 37 °C, proportions of cells bearing Fc receptors in cord blood samples showed striking increments (P < 0.001) when compared with adult lymphocytes. T cell enrichment studies and sequential depletion of cells bearing Fc receptors as well as E-rosette forming cells indicated that the precursors of cells generating Fc receptors in vitro did not arise from cells with Fc receptors or T cell markers.