EXPRESSION OF THE CUTANEOUS LYMPHOCYTE-ASSOCIATED ANTIGEN IN CIRCULATING T-CELLS IN DRUG-ALLERGIC REACTIONS

Background: Mechanisms underlying the production of delayed cutaneous reactions to drugs are poorly characterized. The cutaneous lymphocyte- associated antigen (CLA) is a skin-homing T cell receptor that defines T lymphocytes associated with the cutaneous immune response. We studi ed the percentage and activation phenotype of circulating CLA+ T cells in drug allergic patients and healthy controls. Methods: PBMCs were i solated from heparinized venous blood by Ficoll density gradient. Lymp hocytes were stained for flow cytometry with anti-CLA, anti-CD3 and an ti-HLA-DR mAbs. Five-parameter analysis was performed on an Ortho Cyto ron Absolute flow cytometer. Results: We found increased percentages o f circulating CLA+ T cells in drug-allergic patients compared to contr ols. Moreover, CLA+ T cells from drug-allergic individuals expressed a higher percentage of the T cell activation marker HLA-DR. Conclusions : These results suggest that CLA+ T cells may play a role in the patho logy of delayed cutaneous reactions to drugs. Further studies are in p rogress to elucidate the role of skin-homing T cells in allergic react ions to drugs.