Involved in host defense at the body surface. Causes agglutination and suppresses the growth of the Gram-negative bacterium E.coli K12. Possesses calcium-independent hemagglutinating activity. Homodimer; disulfide-linked. Skin; contained within club cells which are a component of the epidermis in combination with epithelial cells and mucus cells (at protein level). Binds lactose inhibiting its agglutination activity.