The Agglutinating and Sensitizing Capacity of Antisera to Sheep Red Cells after Varying Degrees of Photo-oxidation.

Tyler1 showed that photo-oxidation could cause antisera to become nonprecipitating and nonagglutinating without destroying the ability of the antibodies to combine with the specific antigen. This was shown by the fact that treated antiserum could inhibit specifically agglutination or precipitation by corresponding untreated serum. On the basis of the mutual multivalence theory of Marrack,2 Heidelberger,3 and Pauling4 it was considered that multivalent antibody had been made functionally univalent by the treatment, the term "univalent antibody" being used to designate an antibody that is incapable of causing precipitation or agglutination but which is still able to combine with the antigen. A method more sensitive and direct than that of specific inhibition for demonstrating the presence of specifically combining but nonagglutinating antibody is the antiglobulin sensitization test of Coombs, Mourant, and Race.5 However, this method was not available when Tyler's original experiments were performed. The present experiments show that it can be used with photo-oxidized antisera, and thus one can measure more directly the sensitizing capacity of sera rendered nonagglutinating by this method. There was also a more urgent reason for undertaking the present experiments on the photo-oxidation of rabbit anti-sheep red cell sera. Coombs, Howard, and Mynors6 reported a serological procedure theoretically capable of detecting incomplete or nonprecipitating antibodies to soluble protein antigens. The method using ox red cells, although simple in theory, is rather lengthy to perform. A much shorter method, employing sheep red cells, was envisaged if a nonagglutinating rabbit sheep cell antibody were available.7 Tyler's work showed the possibility of producing this type of antibody by photooxidation. Chemically linked to such an antibody, a soluble protein antigen, such as egg albumin, could be fixed to the surface of sheep cells, which would nevertheless remain stable in suspension. This cell system could then be used for the specific absorption of incomplete antibody, in human serum, to the conjugated protein-the absorption being detected finally by an agglutination reaction using a rabbit anti-human globulin serum. Preliminary studies in this direction have been promising, and a shortened serological procedure for detecting incomplete antibodies to soluble protein antigens has been developed by Coombs and Fiset.8 In the present paper various sheep cell antisera have been examined, before and after varying degrees of photo-oxidation, for their direct agglutinating action and for their combining capacity, as demonstrated by the indirect antiglobulin sensitization test.