TRANSFER OF PASSIVE-IMMUNITY FROM MOTHER TO YOUNG IN A TELEOST FISH - HEMAGGLUTINATING ACTIVITY IN THE SERUM AND EGGS OF PLAICE, PLEURONECTES-PLATESSA L

1. Plaice were immunized against rabbit red blood cells (rbc) and the haemagglutinating activity in their sera and eggs was isolated by gel filtration in Sephacryl S300 SF. 2. A "heavy" (> 6.69 .times. 105 Daltons) and a "light" (< 2.32 .times. 105 Daltons) component of haemagglutinating activity were present in plaice immune serum and eggs. 3. The "heavy" haemagglutinating component had the characteristics of immunoglobulin M (IgM) antibody. 4. By contrast the "light" component was suppressed greatly by monosaccharides but not by 2-mercaptoethanol (2-ME) and it was not precipitable against heterologous rabbit anti-plaice Ig immune serum. Since this "light" component was also identified in the serum and eggs of non-immunized plaice the activity was attributed to non-specific lectin-like activity. 5. The presence of an inducible, high molecular weight, haemagglutinating Ig-like protein in plaice serum and eggs suggests the possibility of transfer of passive adaptive immunity from mother to young in this fish.