Biological characterization of mouse 'early' antibodies.

The ability of mouse antiserum obtained early after immunization to induce passive cutaneous anaphylaxis (PCA) using a short (4 hours) and a long (72 hours) latent period was studied. It was observed that the ability of an antiserum to induce PCA reactions after a short latent period is not correlated with its ability to induce PCA reactions after a long latent period. Furthermore PCA reactions induced 4 hours after sensitization are not abolished by heating of antisera and are completely prevented by mepyramine whereas PCA reactions induced 72 hours after sensitization are completely abolished by heating but are not prevented by mepyramine. It is suggested that antiserum obtained from mice a few days after a single dose of antigen contains at least two biologically distinct antibodies.