“…A consistent observation by various groups is the correlation between increased serum levels of IgA and the extent of the skin manifestations and severity of arthritis [18,25]. However, it has been reported that pso riasis with arthropathy may coexist with a selective IgA deficiency [26], Two groups have reported on decreased IgA levels in psoriatic patients [27,28], The correlation between disease activity and IgA levels [18,25] suggests that IgA is of significance in the pathogenesis of psoriasis. It is attractive to hypothesize that IgA is an 'antipsoriatic factor.…”