IgE antibodies for penicillins and cephalosporins in rats. II. Antigenic specificity of rat anti-penicillin-OvA IgE sera.

Sprague Dawley (SD) rats were immunized with various penicillin-ovalbumin (OvA) in combination with aluminum hydroxide (alum) and thimerosal-killed Bordetella pertussis for the purpose of obtaining rat anti-penicillin IgE sera. In the rat 60-hour passive cutaneous anaphylaxis (PCA) reaction and the hapten inhibition test, a weak cross reaction between penicillin G (PCG) and ampicillin (ABPC) was observed, but not cross reaction was observed between sulbenicillin (SBPC) and other penicillins. Rat anti-6-formamidopenicillanic acid (FPC) IgE serum reacted with PCG-bovine gamma globulin (BGG), ABPC-BGG and SBPC-BGG, but FPC-BGG did not react with rat anti-PCG, anti-ABPC and anti-SBPR IgE sera and the PCA reaction between anti-FPC IgE sera and FPC-BGG was inhibited by FPC, PCG, ABPC and SBPC. These results indicate that the antigenic active sites of PCG, ABPC and SBPC are limited to the acyl side chain moiety of penicillins, while the antigenic active site of FPC is confined to the penicilloyl moiety of the penicillin.