LITHIUM AND PSORIASIS - CYTOKINE MODULATION OF CULTURED LYMPHOCYTES AND PSORIATIC KERATINOCYTES BY LITHIUM

The predominant cutaneous side effect of lithium is the exacerbation o r aggravation of psoriasis, but the pathogenesis is still unclear. The hyperproliferation of keratinocytes and a dense lesional infiltrate o f mononuclear cells are the hallmarks of psoriatic skin lesions, Inter actions between keratinocytes and T cells are thought to be one reason for an increased secretion of proinflammatory cytokines and growth fa ctors, To investigate whether lithium influences cytokines of the 'pso riatic cytokine network', we established a coculture model with kerati nocytes from psoriatic patients and from healthy controls cultured wit h HUT 78 lymphocytes and measured the cytokine levels of Il-2, Il-6, I l-8, IFN gamma and TGF alpha in the culture supernatants after treatme nt with lithium, IL-6 levels were slightly elevated in the supernatant s obtained from psoriatic and control keratinocyte cultures after lith ium treatment, but IFN gamma and IL-2 levels were elevated only in the lithium-treated cocultures with psoriatic keratinocytes, In contrast, these two cytokines were not affected by lithium in HUT 78 monocultur es or in cocultures with normal epidermal cells, We also found slightl y elevated TGF alpha levels in lithium-treated psoriatic cocultures bu t not in control cultures, We therefore demonstrated that lithium infl uences the cell communication of psoriatic keratinocytes with HUT 78 l ymphocytes by triggering the secretion of TGF alpha, IL-2 and, massive ly, IFN gamma. It seems possible that lithium also influences similar parts of the psoriatic cytokine network in vivo.