Complement activity in serum and Mg2+-EGTA plasma from various animals for two haemolytic indicator systems

Stimulation of the titre of a sheep serum factor that is related to the sheep complement system

Serum from most sheep subjected to a single jugular bleeding, repeated bleeding or an intraperitoneal injection of yeast and repeated bleeding, showed an increase in the titre of a serum component called serum factor. Serum factor reached a peak titre 2 to 5 days after treatment started. For some sheep, the titre was elevated for a 9- to 12-day period whereas for others the titre dropped markedly on day 7 followed by a rise on day 9. Serum factor reacts with sheep erythrocytes sensitised with rabbit antibody (sheep E-rabbit A). Serum factor can be detected on sheep E-rabbit A using guinea-pig antiserum that reacts with sheep complement (C). Serum factor is inactivated by heating at 56 degrees C for 30 minutes, but is only partially inactivated at 50 degrees C for 30 minutes. The reaction of serum factor with sheep E-rabbit A is inhibited by chelators of Ca++ and/or Mg++. Serum factor appears to be related to the sheep C system. Preliminary results suggest it may he a component of the classical pathway of sheep C, possibly the second component, C2.

A new hemolytic assay for bovine serum complement and its application during experimental bovine anaplasmosis

A new hemolytic assay for bovine complement is presented. Using this assay we found a significant reduction in bovine serum complement activity during the acute phase of anaplasmosis, and an increase in the sensitivity of the red blood cells (RBC) to bovine complement lysis in vitro. The new hemolytic test is performed with bovine RBC, rabbit anti-bovine RBC serum and bovine serum complement. An isotonic sucrose Tris-buffered saline solution of ionic strength 0.094 and pH 7.2 was found to be adequate for this test. The titres obtained with this new assay, which uses autologous RBC, are comparable with those obtained using the guinea pig RBC assay. The finding of a reduction in bovine serum complement during anaplasmosis may be suggestive of a mechanism responsible for the pathology of this disease.

Conglutination and haemolysis of unsensitized human erythrocytes by bovine serum complement

Unsensitized human erythrocytes (E) were haemolyzed by bovine serum to a titre of 1:16-1:32. In the single dilution beyond the haemolytic endpoint, the cells were conglutinated. In dilutions in which haemolysis occurred, cells were conglutinated before being lyzed. With no or minimal haemolysis, conglutination to 1:32-1:64 occurred in tests using insulin-absorbed serum, serum heated at 50 degrees C for 30 min and in tests incubated at 4 degrees C for 30 min. In two-stage tests, EDTA and Mg2+-EGTA prevented bovine C sensitization of human E for conglutination by bovine serum heated at 56 degrees C for 30 min. EDTA prevented haemolysis, but haemolysis to 1:16-1:32 occurred with serum dilutions containing Mg2+-EGTA. Haemolytic activity was restored to serum heated at 50 degrees C by a factor B-containing fraction. Conglutination and haemolysis were blocked by heating serum at 56 degrees C for 30 min and were reduced to low titres by absorbing serum with zymosan. These results strongly suggest that the conglutination reaction involved the classical activation pathway whereas the haemolytic reaction involved the alternative activation pathway. Thus, with dilutions of untreated or treated bovine serum, two C-dependent reactions and the pathways involved can be demonstrated by using unsensitized human E as an indicator system.