Dinitrophenyl-reactive immunoglobulins in the serum of normal bowfin, Amia calva.

The sera from unimmunized bowfin agglutinate a large variety of red cells. Although they precipitate DNP-BSA they manifest only slight agglutinating capacity for DNP-coated cells. 15S immunoglobulin isolated by DEAE-cellulose chromatography followed by Sephadex G-200 gel filtration possessed a high level of broad reactivity towards unmodified DNP-coated cells, whereas the 7S immunoglobulin isolated by this procedure was inactive. However, following precipitation of whole serum with DNP-BSA both molecules could be recovered in a form which demonstrated specificity for DNP, in that both precipitated DNP-BSA and agglutinated DNP-coated cells but not unmodified cells. The mechanism of activation of the 7S molecule is not known but the data suggest that this immunoglobulin is divalent.