Fowl antibody. I. Some physical and immunochemical properties.

Fowl antibodies to rabbit γ globulin, bovine serum albumin and to ε toxin were studied by means of their reactions with rabbit antisera to fowl globulin. Specific precipitates redissolved either in antigen excess or in solutions of lower salt concentration than those in which they had been formed were used to measure the sedimentation and diffusion coefficients and the electrophoretic mobilities of the soluble complexes of fowl antibody with antigen. Fowl antiserum to any one antigen was found to contain two types of homologous antibodies, derived from different constituents of serum, having the same electrophoretic mobility but giving two distinct bands of precipitation with rabbit anti-fowl-globulin serum. The values obtained for the molecular weights of soluble complexes indicate that one type of antibody has a molecular weight of about 600,000 and the other 180,000, and also suggest that the latter type combined with only one molecule of antigen in antigen excess. Both types of antibody were precipitated by antigen in 0.9 and 8 per cent NaCl; the larger precipitates formed at the higher salt concentration contained more of the low molecular weight antibody, together with another component that was neither antigen nor antibody.