Hemopoietic progenitor cells in atopic dermatitis skin lesions

We have recently shown the expression of lymphoid early developmental marke rs, including CD104, Thy I, CD1a, Pgp-1 and TdT; by the cells constituting atopic dermatitis skin infiltrates. To further characterize the cellular ph enotypes we used an indirect immunoperoxidase assay to analyze sections fro m two atopic dermatitis lesion skin biopsies using the following as first s tep monoclonal antibodies (MAB): anti-CD34, CD2, CD5 and CD7. CD34+ mononuc lear cells and endothelial cells were identified. A strong immunoreaction w as observed for the T-lineage marker CD2 and CD5, but a poor reaction, if a ny, was seen for the CD7. Since CD34+ marrow and blood cells are currently believed to be the major source of the hemopoietic precursors, our data pro vide further substantial evidence supporting the hypothesis that the atopic dermatitis skin cell infiltrate represents an ongoing T-lineage in situ di fferentiation process regulated by the skin epithelial microenvironment The observed defective expression of the CD7 antigen requires further investig ation for its confirmation as a possible constant feature in atopic dermati tis.