What is an Immunoreaction Test?
Frequent repeat vaccinations are not needed for autologous cancer vaccine therapy.
Implementation of Immunoreaction Test (Intradermal Ttest/DTH Response Test)
To check whether or not cellular immunoreaction to autologous cancer tissue has been established in the living body, an intradermal test called “DTH (Delayed Type Hypersensitivity) response test“ is carried out twice (before and after vaccination). The DTH response test, based on a principle identical to that of the tuberculin test (aimed at checking for a history of Mycobacterium tuberculosis infection), allows checking whether or not a cellular immunoreaction took place in individual patients. With this test, only the patient’s cancer tissue fixed in formalin is injected intradermally to check for immunoreaction to cancer tissue.
The DTH response test I, carried out before the first vaccination, is usually negative. This indicates a state free from cancer-targeted cellular immunoreaction (if such reaction is already present, cancer is unlikely to develop). A patient testing positive in the DTH response test II after the third vaccination suggests that immunocompetent cells in the patient’s body were activated by the vaccine, making it likely that cytotoxic lymphocytes (CTL) against the cancer cells have been induced in this patient.
The DTH response test II is sometimes skipped, depending on the hospital.
During both DTH response tests I and II, the size of erythema (redness) formed at the injection site is measured two days after vaccination. If the diameter of the erythemia is 10 mm or larger, the reaction is judged to be “positive“.