Effect of X Rays upon Hemolysin Production in the Rat

Abstract

Rats were irradiated once with X rays (250 kvp, LD₅₀ of 725 r) at various times during the week before and the 5 days after an injection of sheep erythrocytes, and the hemolysin titer followed. Normally, the peak titer occurred 5 to 6 days after antigen injection. Following irradiation, three principal effects were noted. The peak titer was reduced. The attainment of the peak was delayed. The decline in titer after the peak was delayed. No evidence was obtained that irradiation released appreciable and lasting amounts of hemolysin, or accelerated its disappearance. Exposure at 1 to 3 days before antigen injection was the most effective per unit dose, 175 r causing marked inhibition. Exposure within several hours of antigen injection was less effective, and the results tended to be more variable than in other experiments. Exposure at 1 or 2 days after antigen injection required 350 r to produce an inhibition. Although delay in reaching the peak titer was marked, reduction in the peak was not great. As a result, the titers of the irradiated animals were below the controls during the first 10 days, equal to them during days 10 to 14, and above them thereafter. Exposure to 350 to 600 r on the second to fourth days after antigen injection, when measurable titers were about to appear or had appeared in the plasma, led to inhibition within 24 hours.