Transplantable murine plasma cell leukemia with polyclonal gammopathy.

A transplantable plasma cell leukemia cell line, designated as S27, was established from a 12-month-old female New Zealand Black mouse (NZB); serum showed polyclonal elevation of gamma globulin with agarose-agar gel electrophoresis. Immunoelectrophoretic analysis of the serum showed precipitation lines in the IgG1, IgG2a, IgG2b and IgM regions. The amount of serum immunoglobulin increased rapidly with tumor growth. S27 cells proliferating in the spleen contained simultaneously IgG1, IgG2a, IgG2b in the cytoplasm as revealed by indirect immunofluorescence. Membrane immunofluorescence revealed IgG1 on the tumor cell surface. S27 cells were transplantable to syngeneic NZB mice with inoculation of spleen cell suspension, and showed the same histological and immunological findings as those of the original mouse. These findings imply that a single clone of plasma cells has the capacity to produce more than one class of immunoglobulin.