Identification of a protein having hemagglutinating activity in the hemolymph of the silkworm, Bombyx mori.

Hemolymph of Bombyx mori larvae was found to contain activity to agglutinate trypsinized and glutaraldehyde-fixed sheep red blood cells (fixed SRBC). The specific activity of the hemagglutinin changed during development from the fifth instar to the adult with a transient increase just before pupation. This activity was specifically inhibited by glucuronic acid and heparin. The material with hemagglutinating activity was partially purified by gel filtration on Sephacryl S-300. A protein with molecular weight of 260,000 that preferentially binds to fixed SRBC was identified using radioiodinated hemagglutinin. Antibody raised against this protein specifically inhibited the activity of partially purified hemagglutinin, indicating that this protein is essential for hemagglutination.