A phylogenetic classification has been offered as a guide in determining the antigenic relationship among fish.
Neutralization by exhaustion of the passively transferred site and neutralization in vitro lends support to the existence of a common antigen among the Mollusca family.
The same procedure points to the existence of a complex molecule with several antigenic fractions in the Crustacca family. All the fractions seem to be present in the lobster extract; the crab antigen seems to be present in the shrimp extract, while the crab extract does not contain either the lobster or shrimp fraction.
Denaturization by heating decreased the activity of the extracts tested as judged by their skin reactions and estimation of the total protein contents, but in no way altered the structure of the antigen.
The only possible clinical application of the present work is that it might explain positive reactions to certain fish extracts in patients who never ate them, such skin reactions being produced by a common antigen in the extract.