Immunological aspects of psoriasis.

We investigated sixteen patients before and after 1 month of PUVA therapy (three times a week) for circulating immune complexes (CIC) and T-cell markers. CIC were detected by the PEG-C4 assay, using a laser nephelometry determination of polyethylene glycol (PEG, 3.5%) precipitated endogenous C4. T cells were evaluated by E rosettes, active E rosettes, anti-HTLA serum and ox EA gamma-rosettes. This latter method investigated mainly T cells bearing Fc receptors for IgG (Tgamma-cells). After 1 month of PUVA-therapy: (a) the cutaneous lesions markedly improved; (b) the mean percentages of E rosettes, active E rosettes, and HTLA bearing cells, depressed before treatment, returned to normal; (c) CIC were found in higher amounts; (d) T gamma-cell numbers decreased simultaneously. The improvement of T-cell levels assessed by E rosettes, active E rosettes and HTLA values was correlated with clearing of skin lesions, as previously reported by others. However, the increase of CIC during PUVA therapy, their correlation with T gamma-cell decrease, and their possible role in the pathogenic chain of psoriasis remains uncertain.