Virus-induced hemolytic anemia in mice.

in this laboratory by strict brother-sister mating (7). These mice have been shown to have a very low incidence of spontaneous leukemia (7). Electron microscopy of spleens and blood from uninfected mice never reveals any virus-like particles. Virus. The origin of the MEV has been described (7). MEV used in the present experiments was obtained from cell-free spleen filtrates of the 23rd to 26th C3Hf/gs mouse passages. Throughout the passage history of MEV, virus potency and pathological manifestations of erythroblastosis have not deviated from the original report (7). Animals were inocu lated i.p. when I to 4 days old with 0.1 ml of the virus preparation. Red Cell Survival. @ â€C̃r-Labeled red cell survival studies were carried out according to a modification of the method described by Donohue et a!. (6). Donor animals were lightly anesthetized with ether, the brachial artery and axillary vein were cut, and blood was collected in heparinized Pasteur pipets. Blood from several animals was pooled and centri fuged and the plasma and buffy coat were discarded. The erythrocytes were washed once with 0.9% NaCI solution and resedimented. To each ml packed erythrocytes was added 1 mCi sodium chromate-5 â€C̃r (New England Nuclear Corp., Boston, Mass., 50 to 500 Ci/g, 1 mCi/ml in 0.9% NaCl solution). Donor cells were incubated at 37°for 45 mm, sedimented, washed twice with NaCl solution, and resus pended in NaCl solution to produce a 20% suspension. Each recipient animal received 0.5 ml of the suspension (0.1 ml packed cells) i.p. Thirty-six hr elapsed before the first samples were drawn to permit complete absorption of red cells from the peritoneal cavity. Initial blood samples were collected from the tail vein in 13-p1 capillary pipets. Subse quent samples were collected at 1 to 3-day intervals. Capillary pipets were stored in plastic vials and all samples from 1 experiment were counted on the same day to eliminate the necessity for calculating radioactive decay.