On the nature of the union of alexin with specific precipitates

Abstract

In continuing studies on the nature of alexin fixation by mixtures of unformed proteins and their antisera, it occurred to the writer to examine whether the alexin fixation which is exerted by specific precipitates was subject to the same conditions that prevail in the case of sensitized cell complexes in their relations to the alexin fractions as first obtained by Ferrata. It is well-known, of course, that by dialysis, by dilution with weak acid in distilled water and by a number of other methods of globulin precipitation, the alexin or complement can be divided into two functional parts, one which comes down with the globulins, the so-called “midpiece” and the other which remains in the albumin fraction, the so-called “endpiece.” Neither of these can produce hemolysis of sensitized cells alone. Together they functionate. The globulin fraction can be bound to sensitized cells, forming the so-called “persensitized cells” which are now hemolyzable by the endpiece alone. The albumen fraction does not become attached or fixed to the sensitized cells except in the presence of the globulin fraction. (The terms midpiece and endpiece are used for the sake of clearness since they are terms which have become etablished in the German literature. Owing to studies which are being made by Mr. Maltaner in this laboratory we feel that a definite nomenclature which assumes an intermediate function of the globulin, fraction, is premature.)

In experiments in which alexin fractions, produced by both the method of Ferrata and by that of Sachs and Altmann, were exposed to union with precipitates, formed in mixtures of beef serum and its antiserum, we have found that the conditions which prevail are entirely analogous to those which govern the attachment of the alexin fractions to the sensitized cells. A specific precipitate may fix the globulin fraction (midpiece) alone. It may fix the albumin fraction (endpiece) in the presence of the globulin fraction. It does not however, fix the albumin fraction (endpiece) by itself. The experiments were in every case controlled by titrations of the alexin fractions and the whole alexin in tubes set up parallel with the main experiment.