Mixed haemadsorption: a mixed antiglobulin reaction applied to antigens on a glass surface. Preparation and evaluation of indicator red cells; survey of present applications.

Mixed haemadsorption should be regarded as an application of the mixed antiglobulin reaction to situations where the antigen is sessile on a glass surface. Antibody attached to the antigen when exposing the latter to an antiserum is traced by red cells carrying an antiglobulin layer which makes them adsorb to the antibody. The indicator cells are prepared by coating them first with a layer of γ-globulin from the animal species, the antibody globulin of which they are intended to trace, and then with a layer of the corresponding antiglobulin. The most effective indicator cells were obtained by attaching antibody to natural receptors on the red cells to achieve their first coating of γ-globulin. The preparation of indicator cells for tracing antibodies from a number of species, including human, is described. The mixed haemadsorption technique is highly specific and has a sensitivity which is comparable to that of the most sensitive serological techniques. Test procedures adapted for different purposes are outlined and a number of applications to experimental and clinical problems are reviewed.