CH50 assay assesses the activity of which immune component?

CH50 assay assesses the activity of which immune component?

• A. Humoral antibody titer
• B. Coagulation cascade
• C. Classical complement pathway
• D. Cell-mediated cytotoxicity

Answer: (C)

The CH50 test evaluates the functional activity of the classical complement pathway. It measures how well patient serum can lyse antibody-coated red blood cells via the classical cascade, with the serum dilution needed to achieve 50% lysis reflecting the pathway’s functional capacity. A normal CH50 means components C1 through C9 are present and working to form the membrane attack complex, while any deficiency or inhibition lowers the CH50. This is distinct from antibody titer (which measures amount of antibody), coagulation factors (clotting system), or cell-mediated cytotoxicity (T/NK cell–mediated killing).

The CH50 test evaluates the functional activity of the classical complement pathway. It measures how well patient serum can lyse antibody-coated red blood cells via the classical cascade, with the serum dilution needed to achieve 50% lysis reflecting the pathway’s functional capacity. A normal CH50 means components C1 through C9 are present and working to form the membrane attack complex, while any deficiency or inhibition lowers the CH50. This is distinct from antibody titer (which measures amount of antibody), coagulation factors (clotting system), or cell-mediated cytotoxicity (T/NK cell–mediated killing).