Passive anaphylaxis in mice with gamma-G antibodies. V. Competitive effects of different immunoglobulins and inhibition of reactions with antiglobulin sera.

Mouse antisera to DNP conjugates were fractionated on agar block electrophoresis, and each fraction was tested for ability to give anaphylactic reactions in mice and guinea-pigs, and on mouse mast cells. Concentrations of IgG and IgG globulin were measured for each fraction, and the results indicate that mouse IgG globulin mediates both the PCA reaction in the mouse and the mast cell sensitization. PCA reactions in guinea-pigs with mouse antisera are mediated only by electrophoretic fractions containing IgG globulin. PCA reactions in guinea-pigs could be blocked by the addition of IgG myeloma containing sera to the sensitizing anti-DNP preparation, but not by addition of IgG or IgG myeloma sera. From six different IgG myeloma sera tested on their capacity to block PCA reactions in mice, five showed strong inhibitory activity whereas the sixth was inactive. However, also IgG and IgG myelomas were found capable of blocking PCA reactions in mice. The passive sensitization of mouse mast cells by purified mouse anti-DNP antibodies could also be blocked by the addition of specific anti-IgG sera. Possible interpretations of these findings are discussed.