Destruction of Erythrocytes During Experimental Fever

A simple analytical model has been worked out for quantitative assessment of temporary shifts in erythrocyte survival curves after labelling with radioactive tracers. This model was applied to 51Cr and DF32P curves from rabbits exposed to experimental fever induced by either bacterial pyrogen, heated milk or external heating in a climatic chamber. Thereby a quantitative expression of the fever‐induced erythrocyte destruction was obtained. In all three methods for elevating the body temperature experimentally the studies showed an increased loss of activity during the fever, either in terms of the slope of the curve segment concerned with fever compared to the pre‐or post‐febrile periods or in terms of the deviation of the observed curves from the expected, spontaneous course in the rabbit. The maximum loss occurred soon after the initiation of fever, and prolongation of the fever period did not cause a continued increase in the destruction of the labelled erythrocytes. A certain correlation was found between the initial action of heat and the magnitude of the erythrocyte destruction. After the cessation of a short‐lasting period of fever the tracer curve again approached the expected spontaneous course, explained by an age‐dependent variation in the heat susceptibility of the erythrocytes. By using the age‐distribution function for rabbit erythrocytes, an explanation of the demonstrated differences in the simultaneous changes in radioactivity and haemoglobin or PCV is attempted. It is concluded that elevated body temperature shortens the mean survival time of the red cells. The average reduction of the red cell mass in the present study was about 15% and the maximum loss about 35%.