Differences in intestinal humoral immunity between healthy volunteers from UK and Bangladesh

Intestinal morphology has been shown to vary geographically. The impact of this variation on gut mucosal humoral immunity is not well-studied. The technique of peroral whole-gut lavage (WGL) with nonabsorbable cleansing fluid can be utilized for the study of gut immune responses in health and disease. In this study, the WGL technique was employed to compare various gut humoral immune parameters in healthy volunteers from Dhaka in Bangladesh and Edinburgh, UK.

Eleven healthy individuals (all male, age range 18-32) from Dhaka and 12 healthy individuals (4 male and 8 female, age range 23-48) from Edinburgh underwent WGL with a polyethylene glycol electrolyte-based solution drunk at a rate of 1 l/h. The first clear effluent was collected and processed. An ELISA technique was used to measure total immunoglobulins (A, M and G) and antibodies to bacterial lipopolysaccharide (LPS: endotoxin) ovalbumin and eotaxin. Immunoturbimetry and radioimmunoassy techniques were used to measure protein (albumin and alpha-1 antitrypsin) and eosinophil cationic protein (ECP), respectively, in WGL fluid (WGLF).

The total IgA, ECP and eotaxin concentrations in WGLF from the Dhaka group were significantly higher than those of the Edinburgh group (P < 0.03, P < 0.002 and P< 0.005 respectively). The IgA antibody level against the core oligosaccharide of bacterial LPS from several Gram-negative species was significantly higher in the Dhaka group compared to the Edinburgh group (P< 0.0001). Similarly, there was generally higher level of IgA antibody response against the various different LPS core structures of Escherichia coli in the Dhaka group, in particular significantly higher against R1, R3 and R4 LPS cores (P< 0.02, P< 0.03 and P< 0.01 respectively) compared to the Edinburgh group. In contrast to antibacterial antibodies, the IgA and IgM antibodies against ovalbumin were significantly lower in the Dhaka group (P< 0.001 and P< 0.003, respectively) compared to the Edinburgh group.

This study on gut mucosal humoral immunity from two geographically distinct populations suggests that place of residence influences gut mucosal humoral immunity. This difference in stimulation of humoral immunity of the gut might explain different rates of inflammatory bowel diseases in developing and developed countries, and also provides a major challenge for the development of mucosally presented vaccine worldwide.