THE IMMUNOLOGY OF FASCIOLIASIS. I. AUTOFIXATION OF GUINEA-PIG COMPLEMENT.

Complement fixing reactions were observed between normal guinea-pig serum and antigens prepared from flukes of the genus . This activity did not require the presence of any other serum, and at the usual relative concentrations of antigen and serum, the guinea-pig serum was the limiting component. The effect therefore differs from a normal anticomplementary activity of the antigen, and was termed the autofixation effect. In the presence of a gross excess of the antigen, the autofixation effect was inhibited. The antigenic component concerned was demonstrated in preparations from both and , from adult and immature flukes, and from the metabolic products of . It was heat-stable and precipitated in 50 per cent ethyl alcohol, but was soluble in water saturated with ether. Normal sera could be used to absorb the component out of the antigen. The autofixation effect summated with the normal anti-complementary activity of the antigens. In the `Quantitative Complement Fixation Analysis' type of complement fixation test, the control set up to allow for the anticomplementary activity of the antigen will also compensate for this effect. This does not apply with other forms of complement fixation test.