The potential role of serum polyclonal free light chains as markers of immune activation in psoriatic patients

BackgroundPolyclonal free light chains (FLCs) of immunoglobulins include kappa and lambda chains and represent a sensitive marker of activation and/or dysfunction of the immune system.ObjectivesThe aim of this study was to investigate the role of FLCs as markers of immune activation in the management of psoriatic patients treated with biologics.Materials & MethodsThe overall study population included 45 patients affected by mild-to-severe psoriasis with either ongoing biological treatment or without any current systemic therapy. Peripheral blood samples were taken from all patients and 10 healthy subjects in order to determine immunoglobulins, light chains and FLCs by quantitative nephelometric assay. Moreover, antinuclear antibodies (ANA) were detected by immunofluorescence.ResultsPsoriatic patients showed significant increased levels of kappa and lambda FLCs compared to healthy controls. Interestingly, kappa and lambda FLCs values were significantly increased only in psoriatic patients with ongoing biological treatment and, in particular, in responder subjects. Furthermore, both kappa and lambda FLCs significantly correlated with duration of therapy. For patients with FLC levels above normal range and under biological treatment for more than 12 months, the odds of being ANA+was greater relative to patients with FLC levels above normal range but under biological treatment for less than 12 months.ConclusionsIncreased FLC levels may represent a marker of immune reactivation in psoriatic patients treated with biologic agents. We suggest that determining FLC levels has clinical relevance, with a cost/benefit ratio justifying such evaluation in the clinical management of psoriasis.