The association of skin-sensitizing antibody with the beta 2A-globulins in sera from ragweed-sensitive patients.

1. The removal of the beta(2)A-globulins from three sera from treated ragweed-sensitive individuals by immune absorption was associated with the loss of all detectable skin-sensitizing antibody activity as demonstrated by Prausnitz-Küstner testing. 2. Gel filtration studies, with sephadex G-200, indicated that the fractions containing only macroglobulins were devoid of all detectable skin-sensitizing antibody activity. 3. The immune absorption of the gamma-globulins from a serum fraction containing beta(2)A-globulins, gamma-globulins, and a trace of beta(2)M-globulins had no detectable influence on the skin-sensitizing antibody activity. 4. The removal of a portion of the albumin from the allergic sera by immune absorption, with retention of the skin-sensitizing activity, indicated that the loss of skin-sensitizing antibody was not due to non-specific absorption on an antigen-antibody precipitate. 5. No inhibition of the Prausnitz-Küstner reaction was observed when sheep serum, normal human serum, or normal human gamma-globulins were tested in concentrations described. 6. We conclude that the skin-sensitizing antibody activities in the three sera from treated ragweed-sensitive individuals studied were associated with the beta(2)A-globulins.