Bowel permeability and CD45RO expression on circulating CD20+ B cells in patients with ankylosing spondylitis and their relatives

Objective. Ankylosing spondylitis (AS) is reportedly associated with subcli nical endoscopic gut inflammation in up to 57% of patients. Studies of bowe l permeability, however, have not consistently revealed abnormalities in th ese patients. CD20+CD45RO+ expression is associated with increased antigen exposure, and previous work has shown increased expression in this B cell i soform in patients with Crohn's disease and their relatives, correlating wi th intestinal permeability abnormalities, We sought to re-examine intestina l permeability in patients with AS and their relatives, and relate any obse rved alterations in permeability with evidence of increased antigen present ation as assessed by the number of circulating B cells that were CD45RO pos itive. Methods. We studied small intestinal and gastric permeability by measuremen t of excretion of lactulose, mannitol, and sucrose in 60 patients with AS a nd 24 of their first-degree relatives. We also studied expression of CD20+C D45RO+ by flow cytometry in these patients. Results, Both patients and first-degree relatives had significantly increas ed small intestinal, but not gastric, permeability compared to controls. Am ong patients, current users of nonsteroidal anti-inflammatory drugs (NSAID) had significantly increased small intestinal permeability compared to nonu sers, but relatives not using NSAID also had increased permeability. CD20+C D45RO+ expression was increased in one-third of patients but did not correl ate with permeability abnormalities. Conclusion. Patients with AS have altered small intestinal, but not gastric , permeability. NSAID use cannot explain all the abnormality. Bowel permeab ility abnormalities, possibly genetically determined, may antedate developm ent of bowel or joint symptoms. Increased CD20+CD45RO+ expression suggests increased antigen exposure, which may be related to previous or current int estinal permeability abnormalities.