leukoagglutinin
noun
leu·ko·ag·glu·ti·nin
variants:
or chiefly British leucoagglutinin \ ˌlü-kō-ə-ˈglüt-ᵊn-ən 
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Medical Definition of leukoagglutinin
: an antibody that agglutinates white blood cells — compare hemagglutinin