The expression of adhesion molecules in muscle biopsies: the LFA-1/VLA-4 ratio in polymyositis.

OBJECTIVES

The expression of three pairs of adhesion receptors and ligands was examined in 22 consecutive muscle biopsies showing morphological signs of inflammation.

MATERIAL AND

METHODS

The following groups were studied: patients with polymyositis (PM) (n=7), patients with myositis that did not fulfil criteria for PM, i.e. suspected PM (n=5), patients with other diseases, with no clinical signs of inflammatory myopathy (n=6), and a small group of non-PM inflammatory myopathies (n=4). The endothelial expression of ICAM-1, VCAM-1 and E-selectin was evaluated, as was the cellular expression of LFA-1, VLA-4 and SLex. In addition, the expression of MHC class I and II was studied.

RESULTS

The ratio between the number of cells expressing LFA-1 and VLA-4 showed significant differences between the groups, with the lowest values in PM.

CONCLUSION

The LFA-1/VLA-4 ratio should be suitable for diagnostic purposes. Our findings also indicate that the VLA-4/VCAM-1 system is important for chronic T cell inflammation in muscle, in line with findings in other "hidden" organs like joints and the central nervous system.