Polyclonal T lymphocyte proliferation in drug lymphocyte activation test.

Background. We examined the clonality of the specific T cell reaction activ ated with specific drug antigens in patients with a positive lymphocyte act ivation lest. Patients and methods. Ten patients were investigated. Their clinical featur es suggested drug allergy. Six weeks after a skin reaction, skin tests and lymphocyte activation tests were run. For each lymphocyte activation test, we explored the clonality of the T cell proliferation by examining the VJ r earrangement of the TCR gamma locus using polymerase chain reaction and den aturing gradient gel electrophoresis. Results. All samples gave positive lymphocyte activation tests proving in v itro polyclonal T cell proliferation in reaction to a drug. There was no di fference in clonality between the pilot lymphocyte activation test and the lymphocyte activation test after stimulation with phytohemagglutinin or wit h the drug antigen. Discussion. Our findings show that in vitro T cell proliferation induced by a specific drug antigen as disclosed by the lymphocyte activation test is a polyclonal or oligoclonal cell proliferation. This lack of production of a preferential T clone in a T cell-mediated immune drug reaction implies th at many T lymphocytes can recognize the antigen and be stimulated by the sa me drug.