Immunochemical electrophoresis, to identify specific antibodies in the serum. Allergy tests, to determine the presence or absence of antibodies in the blood stream. To define the malfunction, one must identify the specific fault in the system. A conclusion that someone is immunosuppressed should be based on precise and extensive testing. Chemotherapy and radiation therapy sometimes decrease immune function.
Some types of cancer can depress immune function.
In these conditions, successful use of chemotherapy or radiation to reduce or destroy these cancers often causes a return to normal immunocompetence. The notion that cancer represents a failure of the immune system is false.