It has been recognised for many years that blood serum has an inhibitory effect on the hæmolysis produced by many substances, notably saponin and bile salts. Ransom (1), in 1901, observing that cholesterol inhibits the action of saponin, attributed the inhibitory effect of serum to the contained cholesterol. The quantities of cholesterol used in his experiments are far greater than those which occur in serum, and the experiments are inconclusive for that reason. Bayer (2), in 1907, investigated the inhibitory effect produced by serum on the action of the bile salts. He found that cholesterol has no inhibitory effect, that lecithin produces inhibition, but not in the quantities that occur in blood, and that the proteins of the serum are responsible for the inhibition. He calls attention to the results of von Eisler (3), who states that serum globulin inhibits the action of staphalolysin and of tetanolysin, and also those of von Liebermann, who finds that hæmolysis by soaps is prevented by serum albumin (4). Bayer’s researches are, in the main, confirmed by Sellards (5). The investigations of Ludke (6) and of Scandaliato (7), who found that the inhibitory effect of serum is slightly increased after the injection of bile salts, may be mentioned. The conclusions of these authors are unreliable, since inadequate methods of measuring the amount of inhibition were used. References to various points in connection with the inhibition produced by serum
in vivo
and
in vitro
are to be found in the writer’s earlier papers (8, 9, 10).
The Nature of the Inhibitory Substances
. Before proceeding to the quantitative estimations, it is necessary to know which constituents of serum are responsible for the inhibition of saponin and bile salt hæmolysis respectively. Bayer’s results might be taken as conclusive were it not for two considerations: (1) Bayer filtered most of the solutions of bile salts, and lecithin-bile-salt mixtures, whose hæmolytic power he wished to determine, through a Berkefeld filter, and thereafter tested their hæmolytic activity. He states that this procedure has no effect on the time taken for these solutions to produce hæmolysis. This is a fallacy, for a solution of sodium taurocholate will not pass through a filter paper without losing some of its hæmolytic activity, while passage through a Berkefeld filter causes a very marked change indeed (10). It is therefore not permissible to regard the hæmolytic activity of a solution filtered in this way as identical with, or even corresponding to, the activity of an unfiltered solution; (2) Bayer used very rough quantitative methods—he refers to “slight hæmolysis,” “considerable hæmolysis,” etc., and, accordingly, would be able to detect only very marked degrees of inhibition. The same remark applies to the experiments of Sellards.
The inhibitory effect of blood serum on hæmolysis
