Problem statement: NC/Nga (NC) mice produced high levels of ovalbumin (OVA)specific IgG, IgG1 and IgG2a. We previously found deletion polymorphisms in the promoter region of fcgr2b in NC mice. To determine whether this mutation causes a hyper-humoral immune response, we generated congenic BALB/c mice carrying the NC-type fcgr2b allele (NC fcgr2b) and analyzed humoral immune response and FcγRIIB on germinal center (GC) B cells. Approach: BALB/c, NC and BALB/c-NC fcgr2b congenic mice were

more »

... d with OVA 2 times at a 2-week-interval. Levels of OVA-specific IgG, IgG1 and IgG2a in serum were determined by ELISA. Four-color (anti-B220, anti-IgD, 2.4G2 and PNA) flow cytometry analysis was performed on splenocytes obtained from OVA-immunized mice and levels of FcγRIIB in GC (IgD-PNA high ) and non-GC (IgD+PNA low ) B cells were analyzed. Results: Although perturbed up-regulation of FcγRIIB on GC B was observed in congenic mice, levels of OVA-specific Abs were comparable to those in BALB/c mice. Conclusion: NC fcgr2b affects the level of FcγRIIB in GC B cells but that the reduced FcγRIIB expression is not related to enhanced Ag-specific Ab responses in NC mice.