Trypanosoma lewisi: Immunohematopoietic interrelationships of the infection in normal, hypoxic, and rebound animals

A study has been made of erythropoietic and immune responses in rats subjected to a simulated altitude of 17,000 ft and infected with Trypanosoma lewisi. Observations were also made during the period of rebound (posthypoxic polycythaemia). The erythropoietic response was evaluated on the basis of reticulocyte and hematocrit values in peripheral blood, and the immune response on the basis of the level of parasitemia. When hypoxia and infection were combined, the infection was heavier than in the nonhypoxic animal, as judged by the level of the parasitemia, whereas the erythropoietic response to hypoxia was less intense. Rebound animals, on the other hand, dealt with the infection more effectively, as indicated by the lower level of parasitemia, and the more rapid disappearance of parasites from the blood.