Though the specific mechanisms of CL-K1 in SLE are not clear, CL-K1 may function in the opsonophagocytosis of apoptotic cells by binding to calreticulin (a coreceptor for CD91) like other collectins, such as MBL, SP-A, and SP-D (42). Here, MBL2 is linked to systemic lupus erythematosus.