Streptococcus pyogenes tonsillar infection influences disease evolution in
most of guttate psoriasis patients (GPP), being associated with HLA-Cw6
and a more intense inflammatory infiltrate in skin lesions. Understanding
humoral response against S. pyogenes may shed light to the role of
infections in psoriasis development. Plasma from untreated GPP (n=23)
and healthy controls (HC, n=21) were analyzed for the presence of IgG and
IgA against S. pyogenes extract (SE). Also, circulating CLA+/- T cells from
the same patients were cultured with autologous epidermal cells with or
without SE stimulation. IL17A, IL17F, IFNg and IL-9 were measured in
culture supernatants. According to anti-SE IgA and IgG response GPP
classified in in IgA+IgG+ (18,2%), IgA-IgG+ (72,7%) and IgA-IgG- (9,1%).
The largest population showed the greatest IL17A and IL17F production in
CLA+ T cells cultures. Notably, IgA+IgG- subgroup was absent, supporting
the relevance of IgG over IgA in GPP. Increased IFNγ levels were not
associated to CLA+ T cell response. Higher CLA+ T cells dependent IL9
response was observed in patients with IgA-IgG+ against SE. No
correlation between anti-Streptolysin O antibody titer and IgG/A was
observed, indicating that these are independent indicators of S. pyogenes
infection. Uneven GPP distribution according to immunoglobulin levels
indicate a preferential IgG response related to acute tonsillar infection, in
comparison to IgA. Specific IgA levels in GPP may be a useful marker to
stratify GPP patients.

Streptococcus pyogenes specific IgG, but not IgA, identifies guttate psoriasis patients with increased CLA+ T cells IL17A, IL17F and IL9 producters