Autoimmune hemolytic anemia involves which hypersensitivity mechanism?

Autoimmune hemolytic anemia involves which hypersensitivity mechanism?

• A. Type II hypersensitivity
• B. Type I hypersensitivity
• C. Type III hypersensitivity
• D. Type IV hypersensitivity

Answer: (A)

Autoimmune hemolytic anemia is driven by antibodies binding to antigens on the surface of red blood cells, marking them for destruction. This antibody-mediated attack activates complement and leads to either intravascular lysis or removal by splenic macrophages. That antibody-mediated, cell-targeted destruction is the hallmark of type II hypersensitivity. The direct antiglobulin (Coombs) test would be positive because antibodies or complement are attached to the red cell surface. In contrast, type I is IgE-mediated allergy, type III involves immune complex deposition, and type IV is T-cell–mediated delayed hypersensitivity.

Autoimmune hemolytic anemia is driven by antibodies binding to antigens on the surface of red blood cells, marking them for destruction. This antibody-mediated attack activates complement and leads to either intravascular lysis or removal by splenic macrophages. That antibody-mediated, cell-targeted destruction is the hallmark of type II hypersensitivity. The direct antiglobulin (Coombs) test would be positive because antibodies or complement are attached to the red cell surface. In contrast, type I is IgE-mediated allergy, type III involves immune complex deposition, and type IV is T-cell–mediated delayed hypersensitivity.