Only isotype that crosses the placenta (provides infants with passive
immunity that starts to wane after birth).

IgA1 found in the

lgA protease is an enzyme produced by

Selective ____ deficiency ,Most commonly these patients are asymptomatic, but classically this immunodeficiency predisposes to recurrent sinopulmonary and GI tract infections

Contributes to immunity to parasites (intestinal worms) by activating eosinophils.

Binds mast cells and basophils; cross-links when exposed to allergen

Unclear function.
Found on surface of many B cells and in serum.

Direct microbial killing (cell lysis)

Opsonization and Clearance of immune complexes

act as anaphylaxis mediators.

Attraction of phagocytes by chemotaxis

are the two 1° opsonins in bacterial defense; enhance phagocytosis.

The pathway forms a C3 Convertase, C4b2b, which splits C3 into two
fragments; the large fragment, C3b, can covalently attach to the surface of microbial pathogens and opsonize them

Increases risk of severe, recurrent pyogenic sinus and respiratory tract infections

Inhibitors for complement system help prevent complement activation on self-cells ex. RBCs

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The fungal cell wall contain