STUDIES ON THE CONGLUTINATION REACTION, WITH SPECIAL REFERENCE TO THE NATURE OF CONGLUTININ

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Abstract
Dilution of plasma with more than an equal volume of saline soln. destroys its ability to produce conglutination of red cells sensitized by univalent antibody. This can be correlated with Pedersen''s work showing that X-pro-tein is readily dissociated by dilution. Plasma has a higher conglutinating activity than serum. Aside from precipitating fibrinogen, heating at 56[degree]C for 1/2-hr. has no harmful effect on conglutinin. Fetal blood and serum yield much lower conglutination titers than adult plasma and serum, indicating that fetal blood is deficient in conglutinin. The fortification of plasma by mixing 4 parts of it with 1 part of 25% human albumin soln. markedly increases its conglutinin content as shown by a 4-fold increase in conglutination titers obtained; addition of less or more than this optimal amt. results in lower titers. Similar results were obtained by fortifying plasma with [gamma] globulin. Albumin solns. with < 12.5% conc. had little or no conglutinin activity; similarly, globulin solns. of < 4.6% gave only relatively low titers when used as conglutinin. Yet, mixtures of these dilute solns. in certain opt. proportions yielded solns. with conglutinin activities considerably higher than that of pooled plasma. The expts. described support the theory that clumping of cells by univalent antibodies in plasma media takes place in 2 stages, namely, (1) specific adsorption of univalent antibodies, and (2) non-specific adsorption of conglutinin by the sensitized cells causing them to stick together. The expts. further support the concept of conglutinin or X-protein as a colloidal aggregate of plasma proteins. Finally, they demonstrate that the intensity of the clumping (conglutination[long dash]not agglutination) depends on the quantity and quality of conglutinin, and not merely on the total protein content of the medium of suspension.