Systemic lupus erythematosus-like graft-versus-host (GVH) disease was induced in 10-week-old male (C57BL/10 X DBA/2) F1 mice by the intravenous injection of spleen and thymus cells (2:1) from 10-week-old male DBA/2 mice. GVH mice were bled at regular intervals 1 month after injection. Antibody to nuclear antigens (ANA) were detected by immunofluorescence using HEp-2 cells as substrate, and antibody to histones and DNA were detected by enzyme-linked immunosorbent assay (ELISA). The titer and frequency of ANA were found to relate directly to the number of donor cells injected. In order to determine the spectrum of ANA in GVH disease, mice were reinjected with optimum cell numbers (120 X 10(6], and splenocytes from two mice with high titer ANA were fused to mouse myeloma cell line P3/X63Ag8.653. Hybridomas were analyzed for ANA by immunofluorescence and ELISA. Sixty-eight clones were found which secreted ANA. Of these, 59% produced antibody to double-stranded DNA, single-stranded DNA, and/or histones and the remainder gave a variety of nuclear immunofluorescence patterns including speckled, homogeneous, nuclear matrix, and nucleolar. This study indicates that GVH disease provides an excellent source of splenocytes for the production of ANA-producing hybridomas as well as a model for the study of autoimmunity.