T-cell repertoire analysis in chronic plaque psoriasis suggests an antigen-specific immune response

Psoriasis is a chronic inflammatory cutaneous disease of unknown etiology. Activation of T cells is thought to play a major role in the pathophysiolog y of psoriasis. In order to gain insight into the nature of the antigen (su perantigen or nominal protein antigen) involved in psoriatic lesions, we ha ve used a RT-PCR method to analyze the frequency of the 24 T cell receptor V beta chain (TCRBV) subfamilies and the size of the antigen-binding region (CDR3), using the immunoscope assay, in skin lesions of patients with chro nic plaque-type psoriasis, Semi-quantitative analysis showed that no signif icant difference in V beta subfamily usage could be detected in T lymphocyt es infiltrating lesional skin as compared to blood lymphocytes, Alternative ly, determination of the size distribution of the CDR3 of all the V beta su bfamilies revealed only in psoriatic skin a marked TCR oligoclonality defin ed by the presence in 3 to 5 V beta subfamilies of a single predominant CDR 3 size which was associated with a unique V beta-J beta combination. Identi cal patterns of CDR3 length and V beta-J beta combination profiles were fou nd in symetrical lesional sites from two psoriatic patients. This type of s kewed CDR3 size profile is reminiscent of a local stimulation of T lymphocy tes by nominal protein antigens. These data suggest that T lymphocytes infi ltrating plaque-type psoriatic skin comprise expansions of oligoclonal T ce lls in response to stimulation by an antigen present in the skin. (C) Ameri can Society for Histocompatibility and Immunogenetics, 1999. Published by E lsevier Science Inc.