CD4 and autoimmune pancreatitis: Although the pathogenesis of AIP is unclear, studies have found a significant increase in the number of activated CD4 and CD8 positive T cells carrying HLA-DR in the peripheral blood lymphocytes and pancreatic tissue of AIP patients.[17] Okazaki et al reported that, compared to the control group, CD4 + T cells producing interferon-γ in the peripheral blood of patients with AIP increased significantly and their secretion levels increased.