Cyclophosphamide-pretreated homozygous C57BL/6 beige mice (B6 bg) were used as recipients for the transfer of lymphoid cells either of short-living autoimmune homozygous B6 'viable motheaten' mice (B6 mev) or of normal B6 mice (B6+) or B6 bg mice as controls. The grafts had no incidence on the survival of the recipients, whatever protocol used. The [mev----bg] chimeras did not develop the mev external phenotype, but there was a transfer of humoral autoimmunity. Compared to control Compared to control chimeras ([bg----bg] and [+----bg]), recipients of mev cells always showed an increase in anti-single-stranded DNA (ssDNA) antibody titres, reaching 2/3 of the mev ones 40 weeks after the cell transfers. Moreover, the anti-ssDNA were mainly of IgM class, correlating with the higher total IgM level found in [mev----bg] chimeras, thus reflecting the serological phenotype of the mev homozygous mice. Though the adoptive transfer of some mev-type humoral autoimmunity symptoms was clearly achieved in this chimera model, the recipient mice did not suffer from the several other features of the mev syndrome, such as the hyperglobulinemia and the severe pathology. This indicates that microenvironmental influences act in concert with B cells to produce pathology in mev mice.