Activated immunocompetent cells in human skin lymph derived from irritant contact dermatitis: an immunomorphological study

By means of microsurgical lymph cannulation, skin lymph was sampled in the course of a sodium lauryl sulphate (SLS)-induced irritant contact dermatitis in human volunteers. The lymph cells were isolated by centrifugation, and then characterized immunocytochemically using different monoclonal antibodies, and in the late phase of the skin reaction also by electron microscopy. Analyses of lymph cells before the induction of the contact dermatitis revealed median values of about 60% T cells (CD4/CD8 ratio about 2:1), 4% Langerhans cells (LCs), and 1% B cells. The remainder were varying proportions of erythrocytes and uncharacterized cells. During the skin reaction, and even after resolution of the clinical signs of dermatitis, a relative and absolute increase of T and B cells, as well as of HLA-DR positive cells, paralleled the previously reported increase of LCs; a high percentage of the T cells were CD4 and CD8 negative. In addition, surface markers such as CD11a, CD25, CD54 and CD58 were detected on lymph cells sampled during the irritant skin reaction. Cell rosettes observed in the lymph throughout the experiment were analysed in the late phase of the skin reaction, and showed a central LC with three to five peripheral, in part activated, T cells, ultrastructurally revealing gap junction-like structures between the two cell types. These data indicate that immunocompetent cells in the skin are activated by a variety of non-immunological stimuli such as operative trauma and irritant contact dermatitis.