Differential behaviour of three soluble membrane molecules in sera and suction blister fluids from lesional and non-lesional skin of psoriatic patients: Comparison with skin of normal donors

Three soluble membrane molecules, intercellular adhesion molecule-1 (sICAM-1), interleukin-2 receptor (sIL-2R) and beta-2-microglobulin (B2M), were measured in suction blister fluids obtained from lesional and non-lesional skin of 20 psoriatic patients (using the Kiistala method). Sera and skin blister fluids of 10 normal subjects were used for comparisons. All these molecules were detected in all the sample types, but showed different behaviour. In fact, sICAM-1 and B2M levels found in the blister fluids were lower than the levels found in patients' sera. On the other hand, sIL-2R levels detected in lesional fluids were higher than those found in both the sera and the non-lesional fluids. A gradient of concentrations was observed for sICAM-1 which declined from lesional to non-lesional fluids to normal skin fluids. The patients' sera showed higher levels of the three molecules than the normal sera and a significantly high correlation was found between the involved skin blister fluids (ISFB) and uninvolved skin blister fluids (USBF) amounts. Furthermore, the serum levels of the three molecules directly correlated with the levels observed in USBFs and, in the case of sICAM-1 and sIL-2R, also with ISBFs. Finally, the B2M amounts measured in ISBFs were correlated with the PASI scores. The possible mechanisms influencing the concentrations of the soluble molecules detected in the blister fluids are analyzed.