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. M-shaped tetramer of two CD180-LY86 heterodimers. B-lymphocytes and spleen. Not detected in thymus, kidney, muscle, heart, brain or liver. Belongs to the Toll-like receptor family.