ELISA Serology for Antibodies Against Chlamydia trachomatis in Crohn's Disease.

Background: Recently we reported IgA anti- Chlamydia antibodies in patients with Crohn's disease (CD), in particular in four patients from a single family of six with CD.

Methods: We studied sera from four cohorts from the north of France. These were identified as: EPIMAD (80 pediatric onset CD and 20 pediatric onset ulcerative colitis), MINOTOR (148 adult onset sporadic CD and 50 adult onset ulcerative colitis), Grande Famillies (50) and matched controls for the Grande Famillies cohort (49). Sera were tested using commercial anti- Chlamydia trachomatis (LGV2:434) IgG and IgA human enzyme-linked immunosorbent assay (ELISA) kits. Cutoff for positivity was 11.0 standard units.

Results: Patients with sporadic CD, unaffected first degree relatives from multiplex families and ulcerative colitis patients had no greater serologic reactivity than controls. However, multiplex families' patients had twice as many positives as the other groups: for IgG 20% vs. 8%; for IgA 20% vs. 10%.

Conclusions: Though not attaining statistical significance, the data showed that familial CD patients had greater exposure to C. trachomatis than sporadic CD patients, supporting our earlier results from one family from the north of France. More specific serologic tests based on outer membrane proteins will need to be employed against the various Chlamydia species with zoonotic potential.