The utilization of one human lymphoblastoid cell line in fusion experiments with peripheral blood lymphocytes from patients with systemic lupus erythematosus (SLE) has made it possible to define efficient and reproducible conditions for the production of anti-DNA-secreting human-human hybridomas. This investigation, using the human lymphoblastoid cell line GM 4672 fused in the presence of 44% polyethylene glycol with lymphocytes from SLE patients, demonstrated a maximal yield of 22.8% hybridomas, 17% of which produced anti-DNA antibodies. We were able to define, in two independent laboratories, that the maximal yield of hybridomas occurred when the lymphocyte to GM 4672 cell ratio was 1:1 and cells were seeded in 2.0 ml wells at a concentration of 4 X 10(5) cells/well. This report demonstrates the reproducibility of human-human hybridoma production with the GM 4672 cell line and the establishment of efficient conditions for the production of anti-DNA autoantibodies from SLE patients.