Precocious and enhanced functional maturation of B lineage cells in New Zealand Black mice during embryonic development.

Previous reports suggest that large numbers of immunoglobulin-secreting cells appear in tissues of NZB strain mice from the time of birth. In this study, we investigated the development of B lineage cells during embryonic life and found that they were present 2-3 d earlier and in higher numbers in NZB embryos than several other strains of mice. That is, liver cell suspensions from NZB embryos contained larger numbers of surface Ig (sIg)- cells that could form B cell colonies in mitogen-dependent semisolid agar culture. Sephadex G-10-adherent cell depletion diminished numbers of colonies and this was partially restored by addition of humoral factors. The latter were partially purified from serum of very young NZB mice. These findings document that abnormal changes take place in B lineage cells and possibly also in cells that regulate their maturation in NZB strain mice at a very early stage of development.