Manipulation of the Humoral Immune System and the Host Immune Response to Infection

The humoral immune system comprises elements that, in part, provide protection against invading organisms. This chapter discusses the effects of manipulating the humoral immune system on the risk of developing microbial infections. Plasmapheresis (also called plasma exchange) has been utilized as a therapy for a limited number of immunological diseases that are caused by autoantibodies. Plasmapheresis has several possible benefits. First, plasma exchange may remove a portion of pathogenic autoantibodies. Second, removal of some circulating immune complexes may be achieved by plasmapheresis, although it has almost no effect on tissue-bound immune complexes that may be formed in situ. Specific methods, such as specific immunoadsorption methods, have been developed to remove specific pathogenic antibodies. Immunoadsorbents have been developed that remove immunoglobulins nonspecifically or that remove specific antibodies selectively. Elements of innate immunity such as natural antibodies and complement have clearly been shown to play an important role in host resistance against microorganisms. Experimental and clinical studies are needed to fully appreciate the beneficial and harmful effects of methods that interfere with unwanted pathologic effects of elements of the humoral immune system.