The Purpuric Reaction Produced in Animals by Derivatives of the Pneumococcus

Abstract

Julianelle and Reimann 1 have described the purpura that develops in white mice following the intraäbdominal injection of pneumococcal autolysates. This reaction is most evident in those portions of the skin on which hair is either scanty or absent. They concluded that some autolytic derivative of the bacterial cells damaged the endothelium of the capillaries in these areas.

The experiments of Julianelle and Reimann have been largely repeated and extended. One of the most striking features of the reaction is that the purpura produced is seldom evenly distributed over the ears, feet, tail, snout, and genitalia. Even on the ears the distribution may be splotchy while along the tail the reaction is always most irregular, certain points showing a very intense reaction while others may be completely negative. These irregularities as well as the anatomical distribution of purpura suggested that some factor such as a mild trauma might be involved in the localization of the reaction. As a test of this hypothesis several experiments have been carried out of which 2 typical examples may be cited.

Experiment 1. An area of one sq. cm. of the abdominal skin of a mouse was carefully shaved. Immediately thereafter 0.5 cc. of an autolysate of rough pneumococci prepared by the method of Julianelle and Reimann was injected intraäbdominally at a point removed from the shaved area. At 24 hours the shaved lesion was markedly purpuric but the removal of hair from neighboring areas showed these to be free of purpura. A second injection of the autolysate was then given. Twenty-four hours thereafter the freshly shaven areas were purpuric but further removal of hair showed that the adjacent skin was completely clear. It seems reasonable to conclude that the irritation associated with the shaving determined the localization of the purpura.