May cooperate with MD-1 and TLR4 to mediate the innate immune response to bacterial lipopolysaccharide (LPS) in B-cells. Leads to NF-kappa-B activation. Also involved in the life/death decision of B-cells (By similarity). M-shaped tetramer of two CD180-LY86 heterodimers. Expressed mainly on mature peripherical B cells. Detected in spleen, lymph node and appendix. Not detected in pre-B and -T cells. Belongs to the Toll-like receptor family.