Which test is commonly used to evaluate a patient's cellular immune response?

The skin test for antigens is a commonly used method to evaluate a patient's cellular immune response, particularly for delayed-type hypersensitivity reactions. This type of immunological response is primarily mediated by T lymphocytes rather than antibodies.

In a skin test, a small amount of an antigen (such as tuberculin for tuberculosis testing) is injected intradermally. A positive reaction, characterized by erythema and induration at the injection site after 48 to 72 hours, indicates a robust cellular immune response, typically involving T cells that have been sensitized to that specific antigen. This test effectively assesses the functional capacity of the cellular immune response, reflecting the presence of memory T cells related to prior exposure to the antigen.

Other methods like ELISA and Western blot focus more on the humoral immune response by detecting antibodies rather than measuring cellular responses. Flow cytometry, while a powerful technique for analyzing cell populations including T cells, is more focused on quantitating and characterizing cells rather than providing a direct evaluation of the immune response to a specific antigen in a functional context. Hence, the skin test is the most direct method to assess cellular immunity in this context.