Specific Nature of Complement Fixing Antibody in Malaria as Demonstrated by Absorption Tests

We 1 have confirmed the demonstration by Coggeshall and Eaton 2 3 of a specific complement fixation reaction in malaria employing P. knowlesi antigens. The parasites were washed as free as possible of hemoglobin and other blood constituents and dried in vacuo. When ready for use a standardized amount was rehydrated with physiological saline, frozen and thawed, and the supernatant fluid used as antigen.

We have tested sera from 83 patients in whose blood malaria parasites were demonstrated. Seventy-two percent gave a positive complement fixation for malaria at some time during the course of the disease. The positive reaction was correlated with the presence or recent presence of demonstrable parasites but not with the number of parasites. Our results show that a positive complement fixation reaction with our parasite antigen is probably diagnostic of malaria. However, a negative reaction does not rule out malaria.

Sera from 134 individuals presumably free from malaria yielded 127 negative and 7 weakly positive reactions read as 1+ or ±. Forty-three of these sera were known to give a positive Wassermann reaction, 40, a negative Wassermann. One in each group gave a weakly positive reaction with the malaria antigen. It would appear that syphilis does not provoke non-specific reactions with the malaria parasite antigen.

We have further shown that Wassermann negative patients who received induced malaria remained Wassermann negative throughout the course of their treatment, even after they had developed a strongly positive reactivity for the malaria antigen.

Absorption experiments also indicate distinct and unrelated antibodies since treatment of serum with either the malaria or Wassermann antigen removes the specifically reacting substance from that serum without modification of its ability to fix complement in the presence of the other antigen.

For these absorption experiments sera giving 4+ reaction with both the malaria and Wassermann antigens were used.