OBSERVATIONS ON THE RELATION OF THE EYE TO IMMUNITY IN EXPERIMENTAL SYPHILIS
Three experiments are reported in which an attempt has been made to determine the extent to which the eye participates in the general resistance which develops in rabbits during the course of syphilitic infection. Rabbits treated with arsphenamine well after the period when they would be expected to be immune to intratesticular or intracutaneous inoculations were reinoculated with the homologous strain of T. pallidum, the organisms being injected into either the cornea itself or the anterior chamber. Altogether in the three experiments 43 presumably immune animals were injected, 25 into the cornea itself and 18 into the anterior chamber. 41 normal animals were used as controls. In the immune animals 27 or 62 per cent showed lesions in the cornea. 14 of the 43 test animals were inoculated simultaneously in the cornea and in the skin of the back. In 9 of these 14, lesions developed in the cornea although no lesions developed in the skin. The lesions developing in the corneas of the "immune" animals had a longer incubation period on the average, were often of longer duration, and in some instances were more severe than the lesions developing in the control animals. In the case of some animals, also, they showed a greater tendency to recur. The immediate reactions in both the normal and the "immune" animals were entirely comparable and there was no evidence of an accelerated reaction in the test animals. It is concluded that the eye of the syphilitic rabbit does not share to the same extent as other tissues in the general resistant state which develops in that animal during the course of syphilitic infection. Possible explanations for this finding are discussed.