IGHG3 and gastritis: Analysis of the IgG subclasses (IgG1, IgG2, IgG3, IgG4) in patients with arthritis (n = 35) and uncomplicated yersiniosis (n = 49) showed that in patients with gastritis, the prevalence of IgG2 antibodies to Yersinia Yop proteins increased with age and was the highest after the age of 40.