HLA alleles have been associated with psoriasis. Toxin-producing
strains of Staphylococcus aureus behave as superantigens, and
if present in patients, might play a role in the exacerbation
of psoriatic lesions by activating certain V-beta (Vβ) T-lymphocyte subsets. Allele frequencies in 22 patients and 22
controls (alleles determined by DNA/SSP typing) were used to calculate a relative risk
of 4.7 (P<.05) for HLA-Cw6. S aureus was isolated from the throat of 11
patients. Enterotoxins A and C were detected by agglutination in the culture filtrate of one
isolate. The enterotoxin A and/or C genes were detected by PCR in 9 isolates, and
transcripts were detected by RT-PCR in 7 of them. None of the isolates from controls
harbored enterotoxin genes. Vβ expansions were detected by RT-PCR in all 22 patients. Low or
no Vβ expansions were obtained in controls. The association of HLA-Cw6 with
psoriasis in Lebanese concurs with that reported for other ethnic groups.
Toxin-producing isolates that colonize patients might play a role in the
exacerbation of psoriatic lesions.
