[A comparative study of erythrocytes from 4 animal species in the determination of hemolytic activity in classical and alternative pathways of bovine complement]. / Etude comparee des érythrocytes de quatre espèces animales dans la determination de l'activité hemolytique des voies classique et alterne du complément bovin.

The hemolytic activity of bovine complement activated via the classical or alternative pathways was studied employing as target cells, erythrocytes of sheep, rabbit, guinea-pig and chicken. A spontaneous activation of bovine complement via the alternative pathway by rabbit and guinea-pig erythrocytes at a high level and chicken erythrocytes at a lower degree, was observed. Consequently hemolytic activity following activation via the classical pathway reflects activation via the two pathways when erythrocytes of these three species were used. In spite of a low degree of hemolysis, sheep erythrocytes have been chosen for their high specificity in the evaluation of bovine complement activation via the classical pathway. Activation via the alternative pathway can be performed by the erythrocytes of the three other species studied.

Changes in the haemolytic activity of bovine serum complement by Hypoderma lineatum (insect oestridae) larval proteinases in naive and immune cattle.

Three serine proteinases (hypodermin A, B and C) of the first instar larvae of Hypoderma lineatum have been assayed for their ability to deplete seric complement of naive or immune cattle. In naive cattle complement consumption is initiated by hypodermin B through the sequence C1-C3 at a concentration of 5 micrograms/ml of serum, and by hypodermin A through the sequence of C3-C9 at a higher concentration of 150 micrograms. The third enzyme presenting a collagenolytic activity has no anti-complementary activity even on C1q. In immune cattle a 70% complement depletion through the classical pathway is observed with 15 micrograms of hypodermin B per ml of serum. The two enzymes A and C appear to play a minor role in the complement depletion via the classical pathway. The biological role of each of these enzymes in the parasite-host interrelationships is discussed. The participation of these enzymes in the immediate hypersensitive reactions following systemic treatment of cattle infested by this endoparasite is considered.