Abstract
Introduction: Recent findings revealed that autoimmune gastritis (AIG) is not rare in Japan. Therefore, the accurate diagnosis of AIG is essential in upper gastrointestinal practice. Diagnostic criteria for AIG were established in 2023; however, the conventional fluorescent antibody (FA) method for anti-parietal cell antibody (APCA) titer measurements has low accuracy and is clinically problematic. METHODS: We developed a latex agglutination (LA) method using a new human-derived antigen. Samples subjected to measurements were sera from AIG cases (127 cases, 49 males, average age 65.9 years) and control cases (129 cases, 81 males, average age 66.1 years) provided by the main facility and three affiliated facilities in Japan. APCA in whole serum was measured using the FA and LA methods. RESULTS: The diagnostic ability of AIG using the FA method was as follows: sensitivity of 99.2%, specificity of 41.1%, and an overall agreement rate of 69.9%, with low specificity previously being reported. On the other hand, the new LA method had good diagnostic performance with a sensitivity of 93.7%, a specificity of 95.4%, and an overall agreement rate of 94.5%. CONCLUSION: We developed a new APCA measurement system that will contribute to the accurate diagnosis of AIG. The use of this measurement system in clinical practice will facilitate the diagnosis and treatment of AIG.
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