THE C-X-C CHEMOKINE MIG IS HIGHLY EXPRESSED IN THE PAPILLAE OF PSORIATIC LESIONS

A prominent feature within the histopathological changes of psoriatic lesions is the particular spatial distribution of neutrophils, macroph ages, and T-cells which are considered to participate in the pathogene sis of psoriasis. In this study, an attempt has been made to examine t he microanatomical localization and magnitude of expression of the T-c ell-attractant and -stimulating C-X-C and C-C chemokines Mig, interfer on-inducible protein-10 (TP-10), macrophage inflammatory protein-1 alp ha and 1 beta (MIP-1 alpha and -1 beta), and regulated on activation, normal T-cell expressed and secreted (RANTES). Employing in situ hybri dization, Mig message was strongly and selectively expressed in the up per lesional dermis with pronounced clustering in the tips of the papi llae, whereas expression in normal or uninvolved skin was quiescent. I n contrast, message for all the other chemokines investigated was much weaker or lacking. Expression of Mig transcripts in cell clusters of the papillae was paralleled by Mig inmunoreactivity on endothelial and mononuclear cells. The expression profile, with high levels of Mig vi rtually limited to those lesional papillae with a pronounced infiltrat ion of mononuclear leukocytes, strongly suggests that Mig is produced by a local population of highly activated macrophages and dermal micro vascular endothelial cells. Considering the T-cell-attracting and -sti mulating capacity of Mig and the importance of T-cells in the pathogen esis of psoriasis, this study indicates that this novel C-X-C chemokin e plays an important role as a mediator of T-cell recruitment and acti vation in the papillae and thus contributes significantly to the cytok ine network of inflammation in psoriasis. (C) 1998 John Wiley & Sons, Ltd.