Type I and type II psoriasis show a similar usage of T-cell receptor variable regions

In nonpustular psoriasis, principally two forms can be distinguished [Christophers E. Henseler T: Patient subgroups and the inflammatory pattern in psoriasis. Acta Dermatol Venereol 69(suppl 151):88-92, 1989): Type I frequently shows positive family history, linkage disequilibrium for human leucocyte antigens (HLAs) Cw6, B13 and Bw57 as well as an early onset. Type II manifests itself around the 5th decade, it is more frequently than normal associated with Cw2 and B27. In the light of this association with HLAs an autoimmune pathogenesis has been discussed. In order to investigate the pathogenetic function of T cells we obtained biopsies from patients with type I (n = 10) and type II (n = 10) psoriasis. Three-step peroxidase staining was performed using a panel of monoclonal antibodies directed against five variable (V) regions of the beta chain (V beta 5a, V beta 5b, V beta 6, V beta 8, V beta 12) and one of the alpha chain (V alpha 2) of the T cell receptor (TCR). Positive or negative selection of a particular TCR V region could not be detected in the demonstrable repertoire. Furthermore, the usage of the V regions under investigation revealed a similar pattern in the two forms of psoriasis.

Excess beta 2 microglobulin promoting functional peptide association with purified soluble class I MHC molecules

T lymphocytes expressing alpha beta receptors recognize antigenic peptide fragments bound to major histocompatibility complex class I or class II molecules present on the surface membranes of other cells. Peptide fragments are present in the two available HLA crystal structures and recent data indicate that peptide is required for the stable folding of the class I heavy chain and maintenance of its association with the class I light chain, beta 2-microglobulin (beta 2m), at physiological temperature. To explain how the exogenous peptide used to create targets for cytotoxic cells bearing CD8 antigen could associate with apparently peptide-filled extracellular class I molecules, we hypothesized that stable binding of exogenous peptide to mature class I molecules reflects either the replacement of previously bound peptide during the well documented beta 2m exchange process or the loading of 'empty' class I heavy chains dependent on the availability of excess beta 2m. In either case, free beta 2m should enhance peptide/class I binding. Using either isolated soluble class I molecules or living cells, we show here that free purified beta 2m markedly augments the generation of antigenic complexes capable of T-cell stimulation.

C-type particles are inducible in Se-Ax, a continuous T-cell line from a patient with Sézary's syndrome

Se-Ax is a continuous mature T-cell line that we have established from a patient with Sézary's syndrome. An important finding was that the Se-Ax cell line required human serum for initial growth. Here we show that transfer of the permanent cell line to a medium deficient of human serum induces production of C-type retroviral-like particles with a unique morphology. Ultrastructurally, these particles are 120 nm in diameter with hexagonal shape, and show a small, centrally located round core of 30 nm. They are observed only extra-cellularly; typical budding, however, is not found. Both by serological testing and molecular analysis we substantiate the morphological conclusion that these particles do not represent common human or animal retroviruses. The inducibility of the particles may be a hint as to a possible endogenous origin.