William A. Hook

ANTICOMPLEMENTARY EFFECTS AND COMPLEMENT ACTIVITY OF HUMAN SERA.

Conclusion The probit transformation for the plotting of immune hemolysis produced by measured amounts of fresh human serum was found to be suitable for titration of complement. Serum from a patient with a high level of C′ activity was found to become highly anticomplementary when heated to 56°C for 30 minutes, but inactivation by heating for 30 minutes at 52°C or below produced little anticomplementary activity in this serum. Addition of an equal quantity of 9% bovine serum albumin prior to heating also prevented the expression of the anticomplementary activity. Ability of serum to become highly anticomplementary as a result of heating is not necessarily associated with diminished activity of its endogenous complement. Conversely, sera with low levels of C′ may not become anticomplementary as a result of heating.

Effect of pH on human complement activity.

WHILE investigating the effect of acetylsalicylic acid (aspirin) on complement (C′) activity, it was observed that incorporation of 40 mg per cent of the drug in a well-buffered reagent diluent, 0.15 M triethanolamine buffered salt (TBS) solution1, significantly increased the haemolytic activity of human complement (HuC′)2. Since it was also noted that the drug slightly reduced the pH of the reaction mixture, the studies were extended to investigate the effect of pH. change on HuC′ activity.

Tissue Antibody and Complement Levels in Runt Disease

Summary Complement fixation tests with liver and spleen antigens derived from various animal species showed no increase of circulating tissue antibody levels in rats suffering from runt disease. Complement levels, on the other hand, were markedly decreased and degree of reduction appeared to be related to severity of the disorder.

Antibacterial substances in placentas and serums of mothers and newborn infants.

Summary 1. Serum was obtained from umbilical cords of healthy newborn babies and from their mothers just after delivery. Liquid preparations of placentas were produced by freezing, thawing, comminution and centrifugation. When tested against 7 species of bacteria, sera and placenta showed bactericidal activity, particularly against Gram negative forms. Placenta and cord serum were active against the same organisms as maternal serum from same patient. 2. Maternal and cord sera and placentas contained lysozyme, complement, and properdin. Placenta and cord serum showed a higher concentration of lysozyme than maternal serum. Placental preparations contained less complement and properdin than serums. 3. Heating at 56°C for 30 minutes caused complete loss of bactericidal activity in placental preparations. Absorption with killed bacteria usually caused loss of bactericidal activity, generally against the absorbing organism only, and this specific bactericidal activity could be restored by addition of heated placenta. 4. Placenta contains antibacterial substances of blood but seems to have little or no detectable bactericidal substance of its own. Apparently it protects the fetus from bacterial infection largely by transmitting protective substances from mother and mechanically impeding access of bacteria to the fetus.

Adaptation of the zymosan assay of properdin to animal sera.

Summary The reaction of zymosan with properdin of certain animal species was found to be inhibited in the presence of properdin-free human complement (RP), an essential reagent in the standard assay. The problem was resolved by 1) precipitating the properdin as euglobulin and reconstituting for the assay in properdin-free residues (R3 or endpiece) of human complement, or 2) deferring the addition of RP until properdin-zymosan complex had formed. The methods were applied successfully in the assay of guinea-pig, swine, and canine properdin, but were ineffective in demonstrating properdin in chicken serum.

Effect of storage on sheep erythrocytes used in complement studies.

Summary Sheep erythrocytes stored for periods up to 4 weeks in modified Alsevers solution exhibited significant and progressive increases in susceptibility to immune hemolysis in assays conducted with a constant source of human C′. Moreover, the increased susceptibility to immune hemolysis closely paralleled the changes of osmotic fragility and a tendency to undergo spontaneous lysis. The findings suggested an intrinsic relationship between immune hemolysis and osmotic fragility. It was noted that cells stored longer than 3 weeks in modified Alsevers solution could be unduly fragile and hypersensitive to immune lysis thus rendering them unsuitable for serologic tests.