Sera used for complement-mediated cytolysis can alter B cell function in vitro.
Nonspecific effects of reagents used to selectively isolate lymphocyte subpopulations are most often analyzed according to their influence on cell viability and proliferation. While characterizing monoclonal anti-human B cell antibodies, we detected consistent changes in B cell function between individual donors, no matter which antibody was employed to deplete B cell subpopulations. The source of these alterations was traced to the commercial complement-containing sera used for cytolysis. Different lots of serum from 3 separate commercial vendors and 2 animal species (rabbit and guinea pig) routinely altered B lymphocyte differentiation after stimulation with either pokeweed mitogen or Staphylococcus aureus (Cowan I), while cell viability, lymphocyte subpopulation distribution, and proliferative responses were unaffected.