il2 responsiveness in antigenspecific lymphocyte proliferation test with sulfhydryl drugsensitized murine lymphocytesusing rapid fluorochromasia assay response of murine lymphnode cells lnc sensitized with sulfhydryl drugs to recombinant interleukin 2 ril2 was studied in antigenspecific lymphocyte proliferation test lpt mice were primed with tiopronin tp and gold sodium thiomalate gtm and the secondary response to lnc was measured in a proliferative assay in vitro rapid fluorochromasia assay with propidium iodide rfp was used for the quantitative measurement of lpt instead of 3hthymidine uptake there was no difference in proliferative response to specific antigen between tp or gtmprimed lnc and control ones in contrast a significant proliferation was observed when lnc from sensitized mice were cultured with sensitizing antigen and ril2 the strength of response was dependent on the concentration of ril2 it was considered that adding ril2 to lpt of tp or gtmsensitized mice enhanced antigenspecific lymphocyte proliferative response and the measurement of il2 responsiveness using rfp method might be useful to detect sulfhydryl drug allergy in man