| Abstract: | Analysis of the sera of seventeen patients with a selective deficiency of IgA revealed that 24% gave a precipitin reaction on gel diffusion with normal bovine serum and milk. None of 100 normal adults and only one of approximately 500 patients with various diseases without an IgA deficiency had precipitins when studied by this same technique. Analysis of the nature of this reaction revealed that an IgG type antibody present in the human sera was reacting with the Fc fragment of the IgM present in bovine milk and serum. An immunologically identical reaction occurred with goat and sheep, and reactions of partial identity with horse and pig sera. No reactions were found with sera from other species including man. In two of the IgA deficient sera additional but much weaker precipitin lines were noted with cow milk. These data are consistent with the hypothesis that oral immunization with the highly antigenic macroglobulin present in cow milk was facilitated by the mucosal antibody defect accompanying the IgA deficiency. |
