In type III immune complex reactions, which of the following tests is generally NOT expected to be abnormal?

In type III immune complex reactions, the immune system is involved in the formation of immune complexes that can deposit in various tissues, leading to inflammation and tissue damage. The testing typically assesses abilities related to complement activation or immune complex formation.

The mitogen response test evaluates the proliferation of lymphocytes in response to specific mitogens, which can stimulate T-cell activation and proliferation. In type III immune complex conditions, the primary focus is on immune complex formation and the complement system's response. The mitogen response is usually not impacted by the presence or level of immune complexes because it assesses a different aspect of immune function: the proliferation and activity of lymphocytes.

In contrast, the other tests listed—such as the C1q-binding assay, Raji cell assay, and CH50 level—are more directly linked to complement function and immune complex activity. They are expected to show abnormalities in type III reactions due to the complement system being activated and potentially depleted in response to ongoing immune complex formation and deposition.

Therefore, the mitogen response is generally expected to remain normal in cases of type III immune complex reactions, making it the correct answer.