Demonstration of the mucous hemagglutinin in the club cells of eel skin.

Eel epidermis was subjected to immunocytochemical study in order to clarify the origin of mucus hemagglutinin. Skin mucus extract was applied on a Sephacryl S-400 column. The active fractions of the hemagglutinin, which agglutinated rabbit red blood cells, were collected. These fractions were contaminated with a hemolysin. Therefore, after inactivation of the hemolysin by heating at 45 degrees C for 30 min, they were reacted with rabbit red blood cells. The agglutinated cells were hemolyzed to make a hemagglutinin-cell membrane complex. Rabbits were immunized with the complex, and antisera against the hemagglutinin were obtained. Skin sections of eel were stained immunocytochemically by a peroxidase-antiperoxidase (PAP) method using the rabbit anti-hemagglutinin serum. Positive reaction for the hemagglutinin was seen in club cells, especially in secretory vacuoles. This fact indicates the mucous hemagglutinin is derived from the club cells in eel.