The C57BL/6 nu/nu lpr/lpr mouse. I. Expression of the 'lpr phenotype' in the C57BL/6 genetic background.

The C57BL/6 lpr/lpr mice develop within 3-6 moths a series of abnormalities of their immune system which characterize the 'lpr phenotype' and allow them to be distinguished easily from normal C57BL/6 as well as from C57BL/6 nu/nu: lymphadenopathy, hyperimmunoglobulinemia, high anti-nuclear antibody titers and, less regularly, anti-whole DNA antibody. Though C57BL/6 nu/nu occasionally present auto-antibody too, the combined use of three or four of the aforementioned parameters for each tested animal allows an easy detection of animals presenting the lpr phenotype. In our C57BL/6 lpr/lpr colony, the lymphadenopathy does not seem to start by chance in any lymphoid organ but shows a very strong preferential occurrence in the cervical lymph nodes. These parameters of the lpr phenotype have been used to trace the lpr genes and to construct the C57BL/6 nu/nu lpr/lpr as described in the companion paper.