STUDIES ON THE HEMOLYTIC COMPLEMENT OF THE DROMEDARY CAMEL (CAMELUS-DROMEDARIUS) .2. ALTERNATE COMPLEMENT PATHWAY HEMOLYTIC-ACTIVITY IN SERUM

Fresh camel serum caused lysis of unsensitised red blood cells (RBC) o f chicken, rabbit and guinea pig. Homologous RBC were resistant to lys is. There was only minimal lysis of goat, sheep, rat and cattle RBC. L ysis of heterologous RBC was attributed to the presence of alternate c omplement activity (ACP) in the serum as adsorption with respective RB C and addition of 10 mM ethylene glycol-bistetraacetate (EGTA) in the SVBS diluent did not abrogate the haemolytic activity. Guinea pig RBC were the most sensitive to lysis, giving a mean ACP activity of 41.5 /- 1.8 CH50 units ml(-1). Clotting, followed by storing of blood betwe en 0 and 37 degrees C for 1 h did not significantly affect ACP activit y. However, considerable activity was lost when blood was clotted and stored at 44 degrees C for 1 h, or when serum was kept at 4 degrees C for 24 h. Treatment with zymosan, or incubation at 56 degrees C for 30 min inhibited ACP activity. Maximum ACP activity occurred in the pres ence of 8 mM Mg2+ in the SVBS-EGTA diluent, at pH 7.3 and incubation t ime of 2 h at 37 degrees C. Levels of ACP activity were determined in 79 healthy camels of different age groups, ranging from 3 months to 15 years. Calves between 3 months and I year of age had higher ACP activ ity than camels in the age group of 5 years and above. Highest mean AC P activity of 89 +/- 7.9 CH50 units ml(-1) were recorded in 1-5 year o ld camels (P < 0.0001). The lowest ACP activity was observed in the 10 -15 year old camels (52 +/- 2.9 CH50 units ml(-1)). There was no signi ficant difference in the ACP activity between the sexes.