Attachment of antigens and antibodies to fixed red cells; Their use in rosette and haemagglutination tests; A comparison with fresh red cells

Abstract

Red cells which have been fixed in dimethyl suberimidate (DMS) may be coated with antibodies by the chromic chloride technique. The coated cells are approximately as sensitive in passive haemagglutination tests as coated fresh red cells. Red cells fixed with pyruvic aldehyde or glutaraldehyde cannot be coated with proteins by the chromic chloride method but may be coated directly by simple incubation with the protein at low pH. Cells coated in this way are however less sensitive indicators than coated fresh or DMS-fixed cells. DMS-fixed cells may be permanently dyed with various Procion dyes and antibodies may be attached to them. In rosette assays preserved cells were tested after (a) antibody-coating, as reagents for detection of SmIg on lymphocytes (b) antigen-coating, as model target cells in rosette tests. Attempts to analyse SmIg expression using dyed cells coated with various antibodies were limited by a tendency for non-specific sticking of DMS-fixed cells to mononuclear cells. Antigen coating was more successful. IgG, coated onto dyed cells could readily be detected in a rosette test with the coloured preserved cell clearly seen surrounded by anti-IgG-coated ox red cells. Conditions for optimal storage of antibodycoated fresh red cells were also investigated. It was found that there is no loss of activity in rosette tests for up to three months when fresh red cells are coated with antibody and suitably stored under sterile conditions. Coated fresh cells, even after long storage, showed no tendency to non-specific sticking.