Evidence for Chlamydia in Crohns Disease

Chlamydia causes enteritis in young pigs and calves, and granulomas within intestinal lymphatics. Recently we called attention to the lymphangitis and lymphatic obstruction that occurs in Crohn’s disease. We searched resected tissues from patients for evidence of chlamydia and sera for evidence of previous exposure to chlamydia. Immunohistochemistry and real-time PCR were employed to seek chlamydia in preserved tissues. In the IHC, antibody to C. trachomatis served as primary antibody; in the PCR, primers specific for Chlamydiaceae were employed. Commercial ELISA kits measured anti-chlamydia IgG and IgA against C. trachomatis antigen in sera derived from a population of patients different from that which yielded the tissue specimens. IHC revealed focal positive staining for chlamydia in tissues of 5 of 19 patients. Positive reacting cells occurred within dense inflammation, in sparsely scattered macrophages in the submucosa and subserosa. Tissues from 3 of 22 control subjects were positive. Real-time PCR done on ileal, colonic, and regional lymph node tissues revealed evidence of chlamydia in 3 of 33 patients. Serology for anti-chlamydia IgG revealed 2 positive values in 24 patients, while serology for anti-chlamydia IgA revealed 4 positives among the 24 patients, and 1 positive in the 15 controls. One patient and one control had both elevated IgG and IgA titers. The 4 patients with elevated IgA titers were from a single family of 6 with Crohn’s disease, which had been previously described. Additional consideration needs to be given to the chlamydia species, including those of animal origin, which leave behind little evidence of their previous involvement.