HLA-related lymphocyte responsiveness in psoriasis.

In order to find associations among the genetic, immunological and environmental factors that might be important in the pathogenesis of psoriasis, the relationship between streptococcal antigen- or mitogen-induced lymphocyte responses in vitro and HLA phenotypes was studied in 23 patients with psoriasis. Patients showed an elevated lymphocyte response to somatic A-streptococcal antigens when compared with healthy controls. In contrast, the response to mitogens (PHA, Con A, PWM) was impaired in patients with psoriasis. The impaired mitogen-induced lymphocyte transformation was found mostly in psoriatics with HLA-B13/B17. The elevated cellular immune response to somatic A-streptococcal antigens, on the other hand, was observed mainly in psoriatics without HLA-B13/B17. The results indicate that gene products of the HLA region known to be associated with psoriasis are involved in the cellular immune response, as expected from clinical trials. These findings also provide further evidence of at least two different subtypes of psoriasis, characterized by genetically and immunologically defined markers.