Chapter VIII · SURVEY OF THE FACTS BEARING ON ACQUIRED IMMUNITY AGAINST MICRO-ORGANISMS (continued 2)
Francis G. Binnie translation
[261]
Laveran and Mesnil[363] confirmed these observations, and in addition made careful observations on the mechanism of this acquired immunity. After making several inoculations with blood containing Trypanosomata into white rats, they made a study of the properties of the blood serum of these immunised animals. First they established the fact that this serum exerts no microbicidal action on the Trypanosomata, but it agglutinates them without, however, rendering them motionless:—“The masses may be resolved into rosettes in which the Trypanosomata, united merely by their posterior extremities, have their flagella free and motile at the periphery.”
Laveran and Mesnil then studied the phenomena evolved in the refractory organism. When injected into the peritoneal cavity of immunised rats the Trypanosomata are not acted upon injuriously by the body fluids. They are, however, devoured by the leucocytes. Laveran and Mesnil thus express themselves on this subject: “... we have demonstrated clearly and repeatedly that the Trypanosomata are ingested alive, perfectly isolated and very motile, by phagocytes, and we have followed the details of this process of ingestion which recalls that of the ingestion of spirilla by the leucocytes of the guinea-pig. We consider, therefore, that the immunity is phagocytic in character.”
[262]
The main facts on acquired immunity established in connection with the most diverse micro-organisms, facts just described, may already be said to lead to certain general conclusions. They indicate in the first place that acquired immunity is accompanied by phenomena more complicated than those observed in natural immunity. In the two categories of processes observed in acquired immunity the phagocytic 249reaction is the only one that can be said to be constant. We find it in those examples in which the influence of the fluids of the body is most manifest, as in the experimental cholera peritonitis of the guinea-pig, as well as in those cases where the humoral action is most feeble, as in anthrax or in the Trypanosoma disease of rats. We have, however, still to establish the relations that exist between phagocytosis and the part played by the fluids of the immunised animal, in order that we may, as far as possible, present a general picture of the inner mechanism of acquired immunity against micro-organisms. To attain this result we must place the reader in possession of further well-established facts, and we must postpone its discussion to the following chapter, which will be entirely devoted to the above-mentioned problem.
250