Food-specific serum IgG4 and IgE titers to common food antigens in irritable bowel syndrome.

Introduction: Food hypersensitivity is a common perception among irritable bowel syndrome (IBS) patients. Data from dietary elimination and food challenge studies support an etiopathological role of diet in IBS, but there are no well-established tests to identify food hypersensitivity.

Aim: To compare IgG4 and IgE titers to common food antigens in IBS and controls.

Method: One hundred and eight IBS [52 diarrhea-predominant (D-IBS); 32 constipation-predominant (C-IBS); 24 alternating (Alt-IBS)], and 43 controls were included in the study. IgG4 and IgE titers and skin prick testing (SPT) to 16 common foods including milk, eggs, cheese, wheat, rice, potatoes, chicken, beef, pork, lamb, fish, shrimps, soya bean, yeast, tomatoes, and peanuts were measured.

Results: IBS had significantly higher IgG4 titers (mug/L) to wheat (395 IQR +/- 1,011 vs 0 IQR +/- 285, p < 0.001), beef (1,079 IQR +/- 930 vs 617 IQR +/- 435, p < 0.001), pork (481 IQR +/- 379 vs 258 IQR +/- 496, p < 0.001), and lamb (241 IQR +/- 460 vs 167 IQR +/- 232, p= 0.009) compared to controls. These differences were maintained across all three subgroups. The antibody titers to potatoes, rice, fish, chicken, yeast, tomato, and shrimps were not significantly different. No significant difference in IgE titers was observed between IBS and controls. SPT was positive for only a single antigen in 5 of 56 patients tested with the same panel of foods. No correlation was seen between the pattern of elevated IgG4 antibody titers and patients' symptoms.

Conclusion: Serum IgG4 antibodies to common foods like wheat, beef, pork, and lamb are elevated in IBS patients. In keeping with the observation in other atopic conditions, this finding suggests the possibility of a similar pathophysiological role for IgG4 antibodies in IBS.