T cells and the skin

In addition to its role as a mechanical barrier, the skin plays an important role in temperature regulation, vitamin D synthesis and absorption of ultraviolet radiation. The importance of the skin as an immunological organ was not fully appreciated until the advent of immunosuppressive agents such as cyclosporin and tacrolimus, which have a predominant action against T lymphocytes and have been found to be effective in the management of common skin diseases such as atopic eczema and psoriasis. T lymphocytes are of fundamental importance to the immune system. Access from the vascular compartment into the skin is facilitated by adhesion molecules located on the endothelial of dermal blood vessels. Selective upregulation of adhesion molecules occurs in various inflammatory skin diseases and specific skin homing T lymphocytes preferentially enter the skin rather than other organs. T cell have recently been classified into Th1 and Th2 cells based on their cytokine profile. Th1 cells produce interleukin 2 (IL-2) and interferon gamma, important in macrophage activation and cytotoxity, and Th2 cells produce IL-4 and IL-5, important in B cell maturation and humoral immunity. Contact dermatitis and psoriasis are characterised by Th1 cells and atopic dermatitis by Th2 cells. The Th1/Th2 profile is also important in infectious diseases such as leprosy in which polarisation towards tuberculoid or lepromatous disease depends on a predominance of Th1 or Th2 cells, respectively. Future management of diseases affecting the skin is likely to depend on a greater understanding of the infiltrating T cell subsets and appropriate modulation of the Th1 and Th2 profile.(AU)

Contact dermatitis: or detective dermatology - abstract

The technique of patch testing is the recognised method of confirming a suspected diagnosis of allergic contact dermatitis. Routinely, a number of tests are applied at the same time - the so-called standard battery. This paper reports on the introduction of standard battery patch testing on 103 consecutive patients tested between March 1986 and December 1987 at the Dermatology Unit of the University Hospital of the West Indies. The North American Standard battery series was used. Forty percent of the 104 patients had positive tests. The commonest allergens were formaldehyde, 7; p-tert-butylphenol formaldehyde resin, 7 (PTBP is an adhesive used mainly in the shoe manufacturing process); nickel, 6; lanolin, 5 (wool fat used as a base for emollient creams and cosmetics), and thuiran, 4 (rubber chemical). The commonest referral diagnosis were eczema of the hands and feet (31/103) either singly or in combination, chronic leg ulcers with surrounding eczema or delayed healing (23/103), and atopic eczema presenting with unusal features (11/103). The highest number of positive tests was found in patients with the diagnosis of eczema of the feet (10/14); 7 of the 10 were allergic to PTBP, the adhesive in their shoes. These results confirm that patch testing is a useful and cost-effective diagnostic tool. Further battery patch testing should be done in Jamaica, as well as in other West Indian islands, with a view to establishing our own standard battery to replace the American one currently being used (AU)