Experimental delayed type allergy without demonstrable antibodies. I. Absence of cytophilic antibodies.

In guinea-pigs a delayed type allergy against sheep erythrocytes (SE) without detectable circulating antibodies (haemolysins) could be produced by immunization with erythrocyte—antibody complexes. Cytophilic antibodies against SE as measured by adherence of SE to macrophages could not be detected on the macrophages or in the serum of these animals as long as they had no haemolysins. Conversely skin tests were often negative in animals with cytophilic antibodies in serum. These antibodies do not seem to be involved in the allergic reaction. Though cytophilic antibodies only occur in sera with haemolysin titres above 50–200 no constant relation between the titres of both antibodies was found in individual sera. Complete Freund's adjuvant stimulates the production of cytophilic antibodies but they are also produced by immunization without adjuvant.