Several lines of evidence suggest that intelectins recognize microbes and may function as an innate immune defense protein. Tunicate intelectin is an opsonin for phagocytosis by hemocyte. Amphioxus intelectin has been shown to agglutinate bacteria. In zebrafish and rainbow trout, intelectin expression is stimulated upon microbial exposure. Mammals such as sheep and mice also upregulate intelectin expression upon parasitic infection. Increase in intelectin expression upon microbial exposure support the hypothesis that intelectins play a role in the immune system.