Effect of Foreign Protein and of Insulin Administered by Mouth After Ox-Gall.

Abstract

While in the midst of a series of agglutination and precipitin tests on rabbits and guinea pigs the writers came across several news items announcing the success of Professor A. Besredka and his assistant, Dr. Harry Plotz, in securing immunization against typhoid, dysentery and cholera through administering the appropriate vaccine by mouth after a preliminary dose of ox-bile. It seemed worth while to determine whether or not precipitin reactions could be induced by similar treatment and to test the possibility of thus administering insulin. The following experiments were made.

Precipitins. Since experiments were already in progress with antibodies developed against Beta crystallin prepared from the lens of the calf, an extract of this protein was used in these tests. In every case, before treating the animals, samples of their blood were taken and a lens precipitin test was made with the serum, using a 1 to 40 dilution of Beta crystallin as antigen. The tests were invariably negative. The rabbits were next kept without food for 24 hours, then inspissated ox-gall diluted with 10 volumes of water was administered by means of a stomach tube. Following this, Beta crystallin was similarly administered. This procedure was repeated every third or fourth day until 3 such “feedings” were given. Ten days after the last treatment samples of blood were taken and precipitin tests made on them.

Eleven rabbits were used. Of the 9 to which both ox-gall and protein were administered, one died before the final test was made. The serum of the 8 remaining rabbits when testeci with a 1 to 40 solution of Beta crystallin gave positive titers varying in different animals in dilutions of from 1/320 to 1/5120. The 2 controls, one given protein without the gall, the other gall without the protein, remained negative. In these absorption tests the amount of protein used was about double that ordinarily employed in developing precipitin reactions by intravenous injections.