Immunogenicity of Mitsuda Antigen in Guinea Pigs

Abstract

It was already reported that even if Dharmendra antigen produced by chemical treatment of leprom was intracutaneously injected into healthy guinea pigs 8 times at an interval of two weeks, the size of reaction was only less than 5mm, and the injection of Dharmendra antigen produced no immunity. Accordingly, the investigation was made as to what effect was produced by the frequent injection of Mitsuda antigen without chemical treatment.
In the animals to which Mitsuda antigen was intracutaneously injected 6 times at an interval of 2 or 4 weeks, the size of reaction caused by Mitsuda antigen increased from 4mm to 15mm, and the magnitude of the tuberculin reaction and the reaction due to Dharmendra antigen as examined in the 8th and 14th weeks was increased as in the results of the reaction caused by Mitsuda antigen. In consequence, it can be said that the intracutaneous reaction caused by Mitsuda antigen produces immunity against leprosy and tuberculosis.
For the investigation on the cause of these phenomenon, therefore, comparison of each skin reaction was made between the reaction in animals sensitized by heat-killed BCG suspension with the human cutaneous tissue and the reaction in animals sensi- tized by heat-killed BCG suspension only, and the size of reaction due to Dharmendra antigen or tuberculin reaction in the foremer animals was larger than that in the latter animals. This fact proves that the tissue and its component acts as adjuvant, sub- stantiating the mode of a sensitization by the intracutaneous injection of Mitsuda antigen. However, it seems that the injection of Mitsuda antigen into human beings should be carried out with attention paid to the fact that the intracutaneous injection of human cutaneous tissue makes the animals allergic.
Moreover, the size of the intracutaneous reaction in animals sensitized by the heat-killed BCG suspension with Mitsuda antigen is larger than that in animals sensi- tized by only either Mitsuda antigen or the heat-killed BCG with tissue suspension, and then, a mixture of Mitsuda antigen and heat-killed BCG suspension is considered to be effective for the prevention of leprosy.