An interloper into the immunopathogenesis of Behcet’s disease

الملخص EN

The aetiology of Behect's disease (BD) is not known, however, lipopoly- saccharide (LPS) present in the outer membrane of streptococci and gram negative bacteria has been implicated in the aetiopathogenesis of this disease.

Possible explanations include, either cross reactivity between microbial and oral mucosal antigens or microbial infection affecting the immune system.

LPS is a potent activator of monocyte-macrophage cell lineage.

CD14 is a glycoprotein expressed on the surface of mature monocytes -is an important molecule in the immune response and acts as a receptor for the complex LPS and lipopolysaccharide binding protein (LPS-BP).

Binding LPs to CD14 triggers a series of monocyte immune responses including synthesis and release of cytokines by monocytes.

Moreover, a pathogenic role ofT-mediated immune responses, probably mediated by soluble factors in the circulation of patients with BD was suggested.

Therefore, because of the importance of CD14 in the inflammatory response, we investigated its expression on monocytes of patients with BD which seemed to be a good indicator for the immunopathogenetic process leading to the inflammatory process in BD.

Also, we investigated the serum level of interleukin-2 receptors (IL-2Rs) which seemed to be a useful indicator ofT-cell activation in BD.

Monocytes obtainedfrom twenty patients suffering from BD and ten healthy control subjects, were examinedfor the activation differentiation marker CD 14 using flowcytometric analysis.

There was significantly raised expression of CD 14 molecule on monocytes obtainedfrom patients with BD in comparison to the controls (meanfluorescence intensity (MF1) 24.68+5.74 and 7.21±1.45, t=9.39, P<0.001 respectively.

Also the percentage of CD14 positive monocytes was 58.93±8.3 7 for the patients' group and 22.41 ±3.68 for the control group, t 13.09, P<0.001 respectively.

Our study, also, revealed that serum IL-2 Rs levels were higher in patients with BD compared to the healthy controls (t=3.69, p<0.001 H.S.).

When patients were separated into two groups according to the number of active organ systems (Group l:<3Vs group II: >3), the mean concentrations of group I and group II were not significantly different (t=0.62, P=0.27).

Interestingly, a statistically significant positive correlation between sIL-2R levels and both arthritic and thrombo-embolic manifestations was found Therefore, in view of our study, increased CD14 expression in BD indicates increased monocytic activation and may suggest that the triggering agent can be the LPS.

Also serum levels of sIL-2R indicated activation of T-mediated immune response in BD, but this finding may not be useful as a marker of disease activity.