Question

Deficiency in immune system like in c2 complement lead to autoimmune disorder why?

Answer 1

Complement component 2 deficiency is associated with the increased risk of developing an autoimmune disorder like systemic lupus erythematosus (SLE) or vasculitis. Autoimmune disorders happen when the immune system malfunctions and attacks the body's own tissues and organs.  C2 deficiency is genetically inherited and is an autosomal recessive trait.

The classical pathway (CP) is activated by immunoglobulins (antibodies, which also includes autoantibodies) that are bound to antigens either on cell membrane surfaces or in the fluid phase as soluble immune complexes or other tissues. C1q, C1r, C1s, C2, and C4 are the components of the CP. Lack of c2 impairs activation of the complement pathway which leads to diminish the ability to fight infections. The dysfunctional complement system is unable to differentiate which cell it should attack, and it sometimes it attacks normal tissues, leading to autoimmunity.