TCell Activation

The first step in the immune pathogenic cascade of psoriasis is the capture and processing of auto-antigen by Langerhans cells or dendritic cells ("antigen-presenting cells" [APCs]) in the epidermis or dermis, respectively. The nature of the antigen is still unknown. There is, however, some evidence that in genetically predispo sed subjects, keratinocyte-derived peptides may be involved.

The APC-antigen complex migrates to a skin-draining lymph node, where the antigen is presented via major histocompatibility complex II (MHC II) on the surface of the APC to the T-cell receptor (TCR) of the specific naive CD4+ cell, or via MHCI to the TCR of CD8+ T cells respectively. Interaction of the APC-MHC-II/antigen-TCR complex is, however, not sufficient for T-cell activation.

The initial binding of T cells and APCs, as well as stabilization of the cell pair, is mediated by LFA-1 on T cell and ICAM-1 on the APC. This stabilized structure has been referred to as the "immunological synapse" (Fig. 5.1a), formation of which is followed by delivery of the antigen-specific signal (signal 1) and a costimu-latory signal (signal 2), which are also mediated by LFA-1 and ICAM-1. Delivery of signal 1 and signal 2 is followed by binding of cytokines that induce T cells to proliferate (i.e. undergo clonal expansion) and differentiate. Proliferation is thought to be largely mediated by the cytokine interleukin-2 (IL-2).

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Natural Treatments For Psoriasis

Natural Treatments For Psoriasis

Do You Suffer From the Itching and Scaling of Psoriasis? Or the Chronic Agony of Psoriatic Arthritis? If so you are not ALONE! A whopping three percent of the world’s populations suffer from either condition! An incredible 56 million working hours are lost every year by psoriasis sufferers according to the National Psoriasis Foundation.

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