Studies on activation and levels of haemolytic complement of buffalo ( Bubalus bubalis). II. Alternate complement pathway activity in serum

Abstract

Buffalo serum caused lysis of unsensitized red blood cells (RBC) of sheep, goat, rabbit and guineapig. There was minimal lysis of cattle RBC, and homologous RBC were resistant. Lysis of sheep and goat RBC was the result of natural antibodies as adsorption with respective RBC and addition of 8 mmol ethylene glycolbistetraacetate (EGTA) in diluent completely abrogated the haemolytic activity. The lysis of guinea-pig and rabbit RBC was only partially decreased by these treatments, indicating the presence of alternate complement pathway (ACP) activity in buffalo serum. The guinea-pig RBC were the most sensitive to lysis, and 50% CH titre units above 40 ml −1 of serum were obtained. The haemolytic activity of buffalo C for unsensitized guinea-pig RBC was reduced from 47 CH 50 units to an undetectable level by heating at 50°C for 20 min and at 56°C for 4 min. Similarly, treatment with zymosan also inhibited this haemolytic activity. Maximum activation of buffalo ACP occurred in the presence of 4 mmol Mg 2+ in the diluent. Using standardized conditions, ACP activity was determined in sera of 98 healthy buffaloes of different age groups from 1 month to 12 years. Even young calves less then three months of age showed considerable ACP activity (45.60±1.21 CH 50 units ml −1) which increased with age. The peak mean values of 79.79±1.45 CH 50 units was recorded in 2 to 4-year-old animals. However, in all the 11 animals above 4 years of age, the haemolytic activity was greatly reduced and was even less than that in 1 to 3-month-old buffalo calves. Haemolytic activity did not vary between the sexes.