γδ T-cell receptor-positive cells in human skin. I: Incidence and V-region gene expression in granulomatous skin lesions

Background: There have been many reports that γδ T-cell receptor (TCR) + cells respond to mycobacterial antigens in vitro, but there is little available information on human γδ TCR + cells in clinical conditions. Objective: Our purpose was to investigate the distribution and involvement of human γδ TCR + cells in granulomatous skin lesions. Methods: The incidence and V-region gene expression of human γδ TCR + cells was examined in granulomatous skin diseases, including cutaneous tuberculosis and leprosy, by immunohistochemical procedures. Results: γδ TCR + cells in the dermis were increased in most patients with borderline lepromatous leprosy, and they were less frequently found in lepromatous leprosy and erythema nodosum leprosum. Other granulornatous skin lesions, including sarcoidosis, contained only a few γδ TCR + cells. The γδ TCR + cells that were found to be increased in this study were mostly δ TCS1 - , BB3 + , Tiγ A + (Vδ1 - , Vδ2 + , Vγ9 + ). Conclusion: The γδ TCR + cells in human granulomatous skin lesions may respond to some mycobacterial antigens, but they do not appear to be directly involved in granuloma formation.