Further Note on the Relative Protection by Polymorphonuclear and Mononuclear Cells in Local Streptococcus Infection.

Abstract

Our investigations on the protective effect of granulation tissue (Gay and Morrison 1 ) (Gay, Clark and Linton 2 ) against a highly virulent streptococcus introduced into the pleural cavity of rabbits, led us to attribute a predominating if not exclusive rôle to mononuclears as compared with polymorphonuclear cells. In the acute stage of the inflammatory process when polymorphonuclears predominate the animals are fully as susceptible as normal controls. We have never denied that polymorphonuclears have a distinct protective energy with some bacteria and in some locations.

Opie 3 in a recent article has reported similar experiments in the peritoneum and shown that early stages of inflammation (polymorphonuclear) prevent temporarily the invasion of the blood stream by the streptococcus, but further shows in complete confirmation of our results that recovery from such infection depends on the establishment of a later stage of inflammatory exudation. He does, however, suggest that our conclusions as to the negative or actually injurious effect of an excess of polymorphonuclear cells are open to another interpretation. It might be, to paraphrase and extend his remarks, that the sterile irritant (aleuronat) so long as it remains injurious is evidenced by polymorphonuclears and the introduction of a second irritant, the streptococcus, at this period leads to a fatal result. We have often thought of still another objection to our own conclusions, namely, that the pleural exudate in 20 hours is excessive in amount (5-10 cc. on the average) and might actually furnish a favorable location for the streptococcus to multiply. This particularly in view of our later observations that actual destruction of the streptococcus in the protected animals takes place not in the exudate itself but in the granulation tissue of the parietal pleura.