The transgene is expressed in both T cell and B cell lineages.

On a C57BL/6 background hemizygotes show increased numbers of B lymphocytes, Ig-secreting cells and serum Ig, as well as a heightened and prolonged antibody response to immunization. T-cells withstand prolonged culture in the absence of growth factors and are resistant to killing by gamma-radiation, glucocorticoids, ionomycin, PMA, and sodium azide, but not complement, cytotoxic T cells, or Fas ligand. These hemizygotes have a normal total T-cell count and thymic involution rate but show an enhanced response to immunization, and serve as a robust source for the production of B-cells, antibodies T-cell lines or hybridomas.

Although transgenic mice on a (C57BL/6 x SJL)F2 background exhibit a mild increase in spontaneous lymphoma and plasmacytoma occurrence (<10% to 18 months), on the BALB/c and C57BL/6 backgrounds tumor incidence is insignificant. Hemizygotes on a background involving C57BL/6 and SJL (but not on the C57BL/6 background) develop an autoimmune disease characterized by immune complex glomerulonephritis, anti-nuclear antibodies, lymphadenopathy, and myocardial infarction.