GAMMA DELTA T-CELLS AND HUMAN SKIN REACTIVITY TO HEAVY-METALS/

Gamma/delta T cells may act as a first line of defence and respond to stress signals from the surrounding tissue. In the present investigati on the occurrence of gamma/delta T cells was studied in the human skin after application of heavy metal salts by a routine epicutaneous patc h-testing procedure. Gamma/delta cells were not found in normal skin. They were observed in all 14 allergic or irritant patch-test reactions to gold chloride and in 6/8 such reactions to mercuric chloride, wher e they comprised 16 +/- 6% and 15 +/- 6%, respectively, of the CD3(+) cells in the dermis. They were also epidermotropic. Very few of these cells were found in reactions to salts of nickel and silver, except th at they were increased in hair follicle epithelium in a reaction to si lver nitrate. The gamma/delta cells expressed the V delta 2 and the V gamma 2 gene segments and were CD4(-)8(-), indicating that they had th e same phenotype as gamma/delta lymphocytes in the peripheral blood. M oreover, they were 'memory' T cells. These results indicate that gamma /delta lymphocytes play a role in the skin defence against highly reac tive heavy metals.