Age-related macular degeneration (AMD) is a leading cause of blindness in aged individuals. Recent advances have highlighted the essential role of immune processes in the development, progression and treatment of AMD. In this Review we discuss recent discoveries related to the immunological aspects of AMD pathogenesis. We outline the diverse immune cell types, inflammatory activators and pathways that are involved. Finally, we discuss the future of inflammation-directed therapeutics to treat AMD in the growing aged population.

Hereditary angioedema is manifested by attacks of swelling of the extremities, face, trunk, airway, or abdominal viscera, occurring spontaneously or secondary to trauma. It is inherited as an autosomal dominant trait and is due to deficient activity of the inhibitor of the activated first component of complement. The clinical diagnosis can be confirmed by the findings of low levels of C4 or C1 esterase inhibitor activity, or both. Therapy may be divided into three phases: long-term prophylaxis of attacks, short-term prophylaxis of attacks, and treatment of acute attacks. Long-term prophylaxis may be achieved with antifibrinolytic agents and androgens. Short-term prophylaxis with these agents and plasma transfusions has been successful. Specific therapy for acute attacks is not available, but good supportive care, together with a knowledge of the course of the disease, can prevent asphyxiation from airway obstruction. Before the advent of therapy, mortality was reported as high as 30%.

Membrane cofactor protein (MCP; CD46) is a widely distributed C3b/C4b-binding cell surface glycoprotein which serves as an inhibitor of complement activation on host cells. The protein has been purified, multiple cDNAs cloned and sequenced, and the genomic organization determined. MCP belongs to a family known as the regulators of complement activation (RCA) gene cluster. The RCA members are related structurally [possess approximately 60 amino acid repeating motifs termed short consensus repeats (SCR)], functionally (bind C3b/C4b), and genetically (genes are tightly clustered on chromosome 1 at q3.2). Beginning at its amino-terminus, MCP is composed of four SCRs, a ser/thr/pro-enriched region, an area of undefined function, a transmembrane hydrophobic domain, a cytoplasmic anchor and cytoplasmic tail. On SDS-PAGE, MCP migrates as two broad forms with Mrs of 59,000-68,000 and 51,000-58,000. The quantity of each form expressed is inherited in an autosomal codominant fashion. This structural heterogeneity is partly explained by the expression of multiple cDNA/protein isoforms that arise by alternative splicing of ser/thr/pro-rich exons (sites of heavy O-glycosylation) and of cytoplasmic tails. This protein is of interest to immunologists and clinicians because of its role in regulation of the complement pathways and, therefore, inflammation in immune complex-mediated syndromes; to reproductive immunologists on account of its expression on sperm and at the maternal-fetal interface; and to tumor immunologists because of its high expression on malignant cells. The availability of monoclonal and polyclonal antibodies and molecular probes will be helpful in addressing questions about the biology of MCP in these and other areas.

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