Comparison of the Antigenicity of Three Forms of Staphylococcal Toxoid

In the preceding report it was shown that staphylococcal toxin after complete detoxification by the photodynamic action of methylene blue still retains its antigenic property. This note records the results of a preliminary study of the antigenic value of this “methylene blue toxoid” in comparison with 2 other common forms.

Materials and methods. (a) A single lot of toxin, No. 9669F, was used for the preparation of the 3 forms of toxoid. Formol-toxoid was prepared with 0.3% formalin. The alum-precipitated formol-toxoid was made by the method of Wells, Graham and Havens. 1 A third portion of toxin was treated with methylene blue, 1:50,000, and exposed to direct sunlight for 3 hours. The 3 toxoids did not hemolyze rabbit-erythrocytes. Immunization and estimation of antigenic response were done as described in the preceding paper. At each stage the procedures were carried out simultaneously and in identical manner.

The results are summarized in Table I. The small number of animals used does not allow a final conclusion. The results suggest that (A) the M. B. toxoid is about as effective as the formol- and alum-precipitated toxoids, and (B) the M. B. toxoid seems to cause less local reaction than the other forms of staphylococcus toxoid studied.