CHANGES IN CD44 ISOFORM EXPRESSION DURING INFLAMMATORY SKIN-DISEASE

The CD44 family of cell surface glycoproteins is widely expressed in e pithelial, mesothelial ana haemopoietic tissues and is thought to func tion primarily as adhesion molecules. The molecule has an intracellula r, a transmembrane and an extracellular domain. The membrane proximal region of the extracellular domain is of variable structure depending on which of 10 variable exons are involved in coding for this region. Both in vitro stimulated T cells and cytokine stimulated keratinocytes are known to express certain isoforms. In this study we have investig ated whether specific isoforms of the CD44 molecule are expressed on e pithelial cells and lymphocytes in the course of two inflammatory skin diseases, namely lupus erythematosus and lichen planus. Monoclonal an tibodies, specific to the epitopes of the CD44 molecule encoded by v3, v4/5, v6 and v8/9 variable exons and a pan CD44 marker, were used on 10 lupus and 8 lichen planus frozen skin samples and compared with nor mal skin from 9 different body sites. Results failed to show detectabl e levels of variant isoforms of CD44 on lymphocytes in either inflamma tory skin disease, despite evidence of T cell activation. All CD44 var iant isoforms were reduced on the keratinocytes in some sections of lu pus and lichen planus. The results are discussed in the context of the current models for the role of CD44 in the immune response.