"Kappa-macroself Ag#2" transgenic mice express a membrane-bound "macroself" superantigen with specificity for the mouse immunoglobulin kappa light chain (IgΚ). Hemizygous mice are viable and fertile. The transgene is expressed in virtually all cells tested, including lymphoid tissue and bone marrow. B cells expressing the IgΚ-macroself superantigen are absent from the peripheral lymphoid organs while Igl+ B cell numbers are substantially increased. Although bone marrow B cell numbers are unchanged, total peripheral B cell populations are reduced by approximately one half. These mice also express the CD45.1 (Ly5.1 or Ptprca) allele, which is atypical for this C57BL/6 (B6) congenic background, and this marker may be used to track donor cell populations in bone marrow transplantation studies with B6 (CD45.2: Ptprcb) mice.
These "kappa-macroself Ag#2" transgenic mice may be useful to study B cell receptor editing and B cell tolerance in a polyclonal immune system, and to rapidly screen other mutations for potential defects in B cell tolerance.
Genotyping Note: As the transgene expresses a superantigen reactive to immunoglobulin kappa of mouse and may interfere with antibody specificity if using mouse anti-CD45 antibodies, a pre-blocking step using unlabeled mouse IgG:kappa (or equivalent blocking step) is recommended for FACS-typing of the Ptprc (CD45) allele.
