Differential expression of CXCR3 targeting chemokines CXCL10, CXCL9, and CXCL11 in different types of skin inflammation

Recruitment of activated T-cells to the skin is a common feature in a wide variety of inflammatory skin diseases. As CXCR3 activating chemokines; CXCL 10 (IP-10), CXCL9 (Mig), and CXCL11 (IP-9/I-TAC) specifically attract activ ated T-cells, this study addressed the question of whether differences in t he expression of these chemokines correlate with the site and cellular comp osition of the skin infiltrates in different types of inflammatory skin dis ease. Skin biopsies from lichen planus, chronic discoid lupus erythematosus , allergic patch test reactions, psoriasis, and Jessner's lymphocytic infil tration of the skin were investigated for chemokine expression using RNA in situ hybridization, and for the expression of CXCR3 using immunohistochemi stry. The results showed differential expression of CXCL10, CXCL9, and CXCL 11, which correlated with differences in the localization and cellular comp osition of the infiltrates. Whereas CXCL10 and CXCL11 were mainly expressed by basal keratinoctyes, CXCL9 mRNA expression was located predominantly in the dermal infiltrates. Correlation with immunohistochemical data suggeste d that macrophages and activated keratinocytes; were the main producers of these chemokines. CXCR3 was expressed by a majority of both CD4+ and CD8+ i nfiltrating T-cells, suggesting a functional interaction between locally pr oduced chemokines and CXCR3-expressing T-cells. In conclusion, these findin gs indicate that these CXCR3 activating chemokines play a significant role in the recruitment and maintenance of T-cell infiltrates in the inflammator y skin diseases studied. Copyright ((C) 2001 John Wiley & Sons, Ltd.