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Antigens prepared from Fasciola spp. precipitated in agar with antisera obtained from mice or rabbits infected with Fasciola hepatica, and with antisera from cattle infected with F. gigantica, or from rabbits immunized with preparations of adult F. hepatica. In the latter there were at least thirty-eight different antibodies, reacting with both protein and species specific non-protein antigens. The reactions of the antisera from infected animals were less complex. Antisera from infected cattle or mice gave little or no reaction with protein antigens, whereas antisera from infected rabbits reacted predominantly with one of the protein antigens. Certain non-protein components of the somata or metabolic products of the flukes also reacted with antisera from infected animals. These components were not species specific, and appeared to be haptens as they did not react with antisera from rabbits immunized with killed fluke antigen. [ABSTRACT FROM AUTHOR]

Complement fixing reactions were observed between normal guineapig serum and antigens prepared from flukes of the genus Fasciola. This activity did 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 differ from a normal anticomplementary activity at the 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 Fasciola hepatica and F. gingantica, from adult and immature flukes, and from the metabolic products of F. gigantica. It was heat-stable and precipitated in 50 per cent ethyl alcohol, hut was soluble in water saturated with ether, Normal sent 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 'Quantative 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. [ABSTRACT FROM AUTHOR]