Relationships of x-irradiation to the enhancement of Candida albicans infections.

Preirradiation significantly reduced the number of Candida albicans cells required for the ld(50) of experimentally infected mice. The start and extent of recovery of total leukocytes of preirradiated infected mice were proportional to the dose of X rays administered. During 10 days postinfection, heterophils of infected mice preirradiated with 400 R recovered to levels above unirradiated, uninfected controls but did not exceed those of unirradiated, infected animals. On the other hand, the more radiosensitive lymphocytes were depressed greatly, and a limited recovery below normal values was obtained. The lymph to heterophil ratio of uninfected mice irradiated with 400 R recovered to normal values by 11 days postirradiation. However, decreases in the ratio of unirradiated or X-irradiated infected mice showed little recovery. During 6 to 10 days postinfection, a reduction in microhematocrit values after a dose of 400 R alone was not observed when a C. albicans infection was superimposed on X-irradiated mice. This difference was not due to changes in the red blood cell volume which was decreased by 400 R with or without infection, but was attributed to a greater decrease in plasma volume caused by a combination of X irradiation and infection. Reticulocyte counts indicated that recovery from the significant decrease in erythrocyte production caused by 400 R was retarded by a progressive infection. Elevated total serum protein of unirradiated mice at 6 days after infection was attributed to increases in alpha- and beta-globulins. A dose of 400 R limited but did not prevent an increase alpha- and beta-globulins upon subsequent infection. Candida species infection or 400 R or both did not greatly affect the concentration of gamma-globulins. The albumin to globulin ratio of irradiated, infected mice was intermediate between those ratios found after X irradiation or infection.