By recognizing and binding to certain carbohydrate moieties on various pathogens , it can promote the killing of microbes either by acting directly as an opsonin or by activating the lectin complement pathway . however , the function of mbl depends on a certain of levels of serum mbl . mbl deficiency and low levels of serum mbl are the basis for a common opsonic deficiency and are associated with recurrent infections and autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis 然而， mbl功能的发挥有赖于其一定的血清浓度， mbl缺乏或血清浓度过低是引起调理吞噬缺损的根本原因，可增加机体对各种病原微生物的易感性而导致机体反复感染，并且与自身免疫性疾病如系统性红斑狼疮( systemiclupuserythematosus ， sle ) 、类风湿性关节炎( rheumatoidarthritis ， ra )的发生、发展有关。
