Precipitin Reactions of Helminth Extracts

Abstract

The serological technic of Boyden 1 offers a suitable means of investigating the preciptin reactions of some helminth extracts, and of studying the degree of relationship indicated by the tests. The limited research in this field has been done almost entirely with saline suspensions of powdered worms. The content of these suspensions was unknown, thus prohibiting the use of definite amounts of antigen which in turn prevented comparable interpretation of the results. Schwartz 2 and Hektoen 3 studied the precipitin reactions of a few dried helminths using the best methods available at the time.

In the present work fresh worms were extracted with sterile buffered saline, and the resulting extracts were passed through Seitz filters and bottled under sterile conditions. The antisera were produced in rabbits by injecting intravenously extracts having 0.00384 gm. total nitrogen per kilo body weight; they were divided into 4 doses of increasing amounts on alternate days. None of the rabbits were reinjected. The quantitative precipitin tests, constant in titer within ± one test tube as shown by repeated tests, permit accurate readings of an antiserum with its homologous antigen and with heterologous antigens.

The nitrogen content of the helminth extracts, as determined by the Kjeldahl method, is found to be much less than that of the mammalian blood sera studied by Boyden. He finds, also, that the non-protein nitrogen content of the mammalian sera is negligible, whereas the opposite is found with the helminths. For example, in extracts of Dirofilaria immitis, the heart worm of the dog, and in Macracanthorhynchus hirudinaceus, the thorny-headed worm of the hog, the non-protein nitrogen content is apparently as great as the total nitrogen. For these species the total nitrogen is 0.061 and 0.072 gm. per 100 cc. of extract respectively.