Human alloreactive T lymphocyte clones derived from cells invading a rejected kidney allograft, were analyzed for their ability to transcribe eleven cytokine genes under phorbol ester (PMA) plus calcium ionophore (CaI A 23187) stimulation. In addition to the positive signal previously obtained for IL-2 transcripts, strong specific patterns were seen with cytoplasmic dot hybridizations for IFN gamma and GM-CSF mRNAs in all the 17 clones screened. For the remaining transcripts (IL-3, IL-4, IL-5, IL-6, TNF alpha, LT, M-CSF and HILDA/LIF), these techniques proved to be inadequate. Northern-blots were therefore performed on three clones exhibiting different phenotypes (CD4+ CD8- non cytotoxic, CD4+ CD8- cytotoxic and CD4- CD8+ cytotoxic). Positive specific signal with the eleven probes could be obtained. Nevertheless, the IL-6 message was found only in the helper clone and the TNF alpha transcript appeared at a later time point compared to the other cytokine messages (its maximum expression was observed around 24 hours post-stimulation). In conclusion, we demonstrate that under PMA+CaI activation, one clone is able to simultaneously transcribe at least eleven lymphokine genes. Except, perhaps for IL-6, the pattern of lymphokine transcription did not permit us to distinguish between different lymphocyte subsets.