Blood Cytology of Normal Rabbits as an Index of Their Reaction to Experimental Syphilis

Abstract

The possibility that the blood cytology might furnish indices of resistance and susceptibility to disease has been considered in the studies on the blood of rabbits carried out in this laboratory. The procedure has been to make a series of blood counts on groups of young adult male rabbits over a period of weeks or months; the animals were then inoculated with some pathogenic agent, or were kept under observation until a spontaneous disease, such as snuffles, developed. Upon the basis of careful clinical and postmortem examinations, the severity of the disease in each rabbit was quantitatively estimated. An attempt was then made to ascertain whether any relationship existed between the conditions found in the blood before inoculation and the severity of the disease which developed. For these analyses, the mean preinoculation blood cell values for each animal were used. In the case of a transmissible malignant tumor, certain definite relationships were found, some of which have been reported. 1 The present communication is concerned with results obtained in experimental syphilis. 2

Observations were made on 85 rabbits, comprising 9 experimental groups. Each animal was inoculated in one testicle with the Nichols'strain of Tr. pallidum. In each instance, lesions of the inoculated testicle developed, and in the majority of cases, of the uninoculated testicle also; of the 85 animals 46 developed and 39 failed to develop clinically recognizable bone or skin lesions during the 3 months'observation period. Upon the basis of the occurrence of these generalized lesions, the rabbits were classified as 39 resistant and 46 susceptible animals.

The resistant animals had before inoculation significantly higher hemoglobin, lower lymphocytes both per cmm. and in per cent, lower total white blood cells and higher neutrophiles in per cent than the susceptible animals.