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Immunology  ` Immunology—Immune reSponSeS       Immunology  ` Immunology—Immune reSponSeS             SECTIon II       107




                  Complement disorders
                   Complement protein deficiencies
                   Early complement      Increased risk of severe, recurrent pyogenic sinus and respiratory tract infections. Increased risk of
                    deficiencies (C1-C4)  SLE.
                   Terminal complement   Increased susceptibility to recurrent Neisseria bacteremia.
                    deficiencies (C5–C9)
                   Complement regulatory protein deficiencies
                   C1 esterase inhibitor   Causes hereditary angioedema due to unregulated activation of kallikrein Ž  bradykinin.
                    deficiency            Characterized by  C4 levels. ACE inhibitors are contraindicated (also  bradykinin).
                   Paroxysmal nocturnal   A defect in the PIGA gene preventing the formation of glycosylphosphatidylinositol (GPI) anchors for
                    hemoglobinuria        complement inhibitors, such as decay-accelerating factor (DAF/CD55) and membrane inhibitor of
                    A                     reactive lysis (MIRL/CD59). Causes complement-mediated intravascular hemolysis
                                          Ž  haptoglobin, dark urine  A.




































































          FAS1_2019_02-Immunology.indd   107                                                                            11/7/19   3:24 PM
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