Which complement factors are evaluated by CH50?

The CH50 assay measures the total complement activity in the classical pathway, which involves the activation of multiple complement components. The CH50 test specifically evaluates the function of complement components from C1 to C9, allowing for the assessment of the entire classical complement pathway's efficiency in forming complexes that lead to opsonization, lysis of pathogens, and activation of inflammatory processes.

Each complement component plays a crucial role, starting with C1, which initiates the cascade, and flowing all the way through to C9, which is involved in the formation of the membrane attack complex (MAC) that helps to lyse target cells. Evaluating the entire range from C1 to C9 provides a comprehensive overview of complement function, making it crucial for diagnosing various complement deficiencies and related disorders.

Other options focusing on subsets of complement components do not account for the entire classical pathway, which limits their clinical utility in assessing global complement function. For instance, options that only include certain components (like C1, C2, C3, C4 or just C4 to C9) would not provide a complete understanding of the classical complement pathway's capability, as they miss important activating factors and the final components necessary for full functional assessment.