HLA-Cw6 homozygosity in plaque psoriasis is associated with streptococcal throat infections and pronounced improvement after tonsillectomy: A prospective case series.

BACKGROUND: Carriage of the HLA-Cw*0602 allele is associated with a particular set of clinical features and treatment responses in psoriasis. Tonsillectomy can improve psoriasis. OBJECTIVES: We sought to evaluate whether HLA-Cw*0602 predicts a favorable outcome after tonsillectomy of patients with psoriasis. METHODS: This prospective case series followed up 28 tonsillectomized patients with plaque psoriasis for 24 months. The Psoriasis Area and Severity Index, Psoriasis Disability Index, and Psoriasis Life Stress Inventory were used for assessment. Tonsils were swabbed for bacteria and patients genotyped for HLA-Cw*0602. RESULTS: After tonsillectomy, HLA-Cw*0602 homozygotes showed significantly more improvement, compared with heterozygous and HLA-Cw*0602-negative patients. Thus, Psoriasis Area and Severity Index score was reduced by 82% in the homozygous patients compared with 42% and 31%, respectively (P < .001), Psoriasis Disability Index score improved by 87% compared with 38% and 41%, respectively (P < .001), and Psoriasis Life Stress Inventory score was 82% reduced compared with 60% and 54%, respectively (P < .001). The homozygotes more often had psoriasis onset associated with a throat infection (P = .007) and an increased frequency of streptococcal throat infections per lifetime (P = .038). LIMITATIONS: Few patients were included and some data were retrospective. CONCLUSIONS: Homozygous HLA-Cw*0602 carriage in plaque psoriasis may predict a favorable outcome after tonsillectomy.

The anti-microbial peptide LL-37 modulates immune responses in the palatine tonsils where it is exclusively expressed by neutrophils and a subset of dendritic cells.

Antimicrobial peptides are essential elements of epithelial defense against invading micro-organisms. The palatine tonsils are positioned at the entry of the airway and the gut and as such are ideally situated to act as immune sentinels in the pharynx protecting against microbial invasion. Tonsils express a number of antimicrobial peptides including hCAP18/LL-37. Here we clearly define the expression of hCAP18/LL-37 in the tonsils showing unequivocally that hCAP18/LL-37 is mainly expressed by infiltrating neutrophils and follicular CD11c+CD13+HLA-DR+ dendritic cells, rarely by macrophages, and never by the epithelium itself. To explore possible functions for follicle-derived LL-37, we stimulated tonsil mononuclear cells with LL-37 in vitro and observed the secretion of the proinflammatory cytokines CCL5 and CXCL9, expression of IFN-γ and MX-1 and down-regulation of chemokine receptors CCR4 and CCR6 which are involved in tissue-selective T cell trafficking. Taken together, these data illustrate new potential immunoregulatory functions for hCAP18/LL-37 in the tonsils.

Psoriasis--as an autoimmune disease caused by molecular mimicry.

Psoriasis is strongly associated with streptococcal throat infection, and patients have increased occurrence of such infections. Psoriatic lesional T cells are oligoclonal, and T cells recognizing determinants common to streptococcal M-protein and keratin have been detected in patients' blood. We propose that CD8(+) T cells in psoriatic epidermis respond mainly to such determinants, whereas CD4(+) T cells in the dermis preferentially recognize determinants on the streptococcal peptidoglycan that might itself act as an adjuvant. The streptococcal association might reflect the concurrence of superantigen production promoting skin-homing of tonsil T cells, M-protein mimicking keratin determinants, and adjuvant effects of the peptidoglycan. Accordingly, improvement of psoriasis after tonsillectomy should be associated with fewer T cells that recognize keratin and streptococcal determinants.

Isolation of mononuclear cells from tonsillar tissue.

Located on the inside of the throat, the paired palatine tonsils form part of the first major barrier protecting the digestive and respiratory tracts from potentially invading microorganisms. The tonsils have a surface of stratified squamous epithelium that extends into deep and branched crypts lined by reticulated epithelium, which in parts may only be one cell thick. Organized in the sub-epithelial space are B cell rich lymphoid follicles. T cells are mostly located in the extra-follicular spaces with a very high CD4:CD8 T cell ratio. In addition to the T and B cell subsets, six phenotypes of dendritic cells (DC) have been identified in the tonsils: Langerhans cells in the squamous epithelium, germinal center DC, and follicular DC in the germinal center, and another three DC phenotypes that are located in the extra-follicular area (interdigitating DC, plasmacytoid DC, and lympho-epithelial symbiosis-DC). Here, we describe the isolation of tonsil mononuclear cells from fresh human tonsil.