Comparative Quantitative Studies of Guinea-Pig and Rabbit Anti-Hemocyanin Precipitates

Abstract

Summary and Conclusions Quantitative chemical analyses of precipitates of guinea-pig and rabbit-antibody and hemocyanin from the whelk, Busycon canaliculata, have been made at various points in the precipitative reaction-range. Although the number of determinations with any one serum was limited by the amount of serum available from a single guinea-pig, it appeared that the curve of the composition of the precipitate, as indicated by the ratio of Ab N:Ag N, of guinea-pig antibody and hemocyanin, follows the same general pattern as that of rabbit-antibody, as determined by other investigators. Rabbit- and guinea-pig antisera for hemocyanin had approximately the same Ab N:Ag N ratios at corresponding points in the respective reaction-ranges. The amounts of specifically precipitable protein per ml of antiserum were similar in rabbit- and guinea-pig antisera, showing that when a suitable antigen is used, serum precipitins are produced as readily in guinea-pigs as in rabbits. Guinea-pig antisera failed to produce zones of complete precipitation of antigen and antibody, in contrast to rabbit antisera which produced well-defined neutral zones with neither antigen nor antibody in excess. The Dean and Webb optimal ratio, contrary to findings with other antigens, did not fall in the equivalence-zone with either guinea-pig or rabbit antisera for hemocyanin, but far in the region of excess-antigen. This ratio bore no relation to the antibody-content of the various sera. Ratios by volume at the midpoints of equivalence-zones, however, paralleled the respective antibody-content of the antisera.