GROUP-A STREPTOCOCCAL ANTIGEN-SPECIFIC-T LYMPHOCYTES IN GUTTATE PSORIATIC LESIONS

A strong association exists between guttate psoriasis and group A, bet a-haemolytic streptococcal infections. To demonstrate the presence of streptococcal-specific T cells in psoriatic skin, T-cell lines (TLs) w ere established from biopsies of lesions from five patients with gutta te psoriasis, and compared with TLs from five patients with eczema, fi ve with lichen planus, two with pityriasis rosea and three with nickel contact dermatitis. TLs from purified protein derivative (PPD)-induce d delayed hypersensitivity sites in three normal individuals were also studied. All five of the psoriatic TLs responded in a proliferation a ssay to heat-killed isolates of group A streptococci, compared with on ly one eczema, two lichen planus and one pityriasis rosea. The respons e of one nickel contact dermatitis and two PPD TLs to group A streptoc occi was markedly less than to nickel and PPD, respectively. One of th e psoriatic TLs was cloned in the presence of type 5 streptococcal M p rotein. The nine clones obtained were all CD3+, CD4+. CD4 5RO+, TCR al pha,beta+ , gamma,delta- . However, they were all unreactive with anti bodies to TCR Vbeta 5, 6, 8 or 1 2. Eight of the nine clones reacted, to a varying extent, to one or two of three preparations of group A st reptococci expressing different M proteins. The streptococcal response of four consistently reactive clones from this patient was HLA-DR-res tricted and inhibited by anti-HLA-DR antibody in a dose-dependent mann er. On stimulation these four clones secreted high levels of gamma-int erferon and detectable levels of IL-2, IL-10 and granulocyte/macrophag e colony stimulating factor (GM-CSF) depending upon the nature of the stimulus, but no IL-4 or TNF-alpha production was detected. This study has demonstrated, for the first time, that T lymphocytes specific for group A streptococcal antigens can be consistently isolated from gutt ate psoriatic lesions. The role of streptococcal-specific T cells in t he pathogenesis of psoriasis remains to be determined.