Inactivation of the skin-sensitizing antibodies of human allergy by thiols

Reaginic activity associated with IgG immunoglobulin

Five human sera with reaginic activity to a number of allergens were fractionated using anion exchange chromatography. In each serum, fractions which contained detectable IgG and no detectable IgA had capacity to fix to skin and subsequently elicit a P-K reaction. Four of these sera had reaginic activity about equally distributed between fractions containing only IgG and fractions containing mixtures of IgG and IgA. A fifth serum contained reaginic activity to crystalline bovine serum albumin (BSA) and most of the activity was associated with the fraction which contained only IgG. This serum was extensively studied using a variety of techniques and it was confirmed that most of the reagin to BSA in this serum was in those fractions containing only IgG. Since reaginic activity can no longer be considered a unique property of IgA the implications of finding antibody with reaginic qualities in immunoglobulins other than IgA are discussed.

Isolation of rabbit IgA antihapten antibody and demonstration of skin-sensitizing activity in homologous skin

Multiple antibody components of rabbit antisera against p-azobenzenearsonate (R(p)) were studied with respect to their globulin nature and skin-sensitizing activity. IgA antibody was characterized by isolating two IgA-rich fractions from a specifically purified antibody preparation. Examination of these fractions showed that IgA antibodies existed in two molecular forms, one with a sedimentation constant of 7S and the other 9S. Skin-sensitizing activity was examined by a P-K type test and a PCA test with R(p)-rabbit serum albumin in homologous (rabbit) species. Only the 7S but not 9S IgA antibody sensitized rabbit skin. IgM antibody showed no activity and IgG antibody showed very low activity. In contrast, only IgG antibody was active in the P-K type test to sensitize a heterologous species (guinea pig). None of the antibodies of other classes showed sensitizing activity in heterologous skin. The 7S IgA antibody lost its sensitizing activity upon reduction and alkylation, although no change in its molecular size could be observed. The loss of sensitizing activity was not due to the destruction of antigen-binding activity since the treated 7S IgA antibody retained this activity as shown by radioimmunoelectrophoresis and by binding to the specific immunoadsorbent. The 9S IgA antibody was more resistant to these treatments than the IgM antibody and showed no indication of dissociation. The treated 9S IgA also retained antigen-binding activity. Both the P-K type and PCA reactions were considerably stronger when the interval between injections of antibody and antigen was 24 hr rather than 4 to 5 hr.