Hemopoietic restoration in lethally X-irradiated mice injected with peritoneal cells

The capacity of intravenously injected cells from peritoneal fluid, peripheral blood, lymph nodes, thymus, and bone marrow of mice to restore hematopoiesis in lethally X-irradiated (880 rad) isogenic recipients, was investigated. Thirty-day survival and visible colony formation in the spleen were employed as the criteria. Administration of 6 x 10 6 or 11 x 10 6 peritoneal cells, and 6.4 x 10 6 or 15 x 10 6 peripheral leukocytes afforded protection against mortality, and elicited colonies in the spleen; comparable effects were observed after injection of 1.1 x 10 5 marrow cells. The injection of 34 x 10 6 adult lymph node cells or of 9 x 10 6 thymus cells from newborn mice had no effect on mortality, nor did they elicit spleen colony formation. A correlation appears to exist between the capacity of isogenic cells to restore hemopoiesis in lethally irradiated mice, and their ability to elicit visible colony formation in the spleen. Evidently normal peritoneal cell populations and peripheral blood leukocytes contain hemopoietic stem-cell elements, with a frequency 30–50 times lower than among bone marrow cells. No evidence was adduced to support the concept that normal lymphoid tissue lymphocytes give rise to hemopoietic cell lines.