Phenotypes Associated with This Genotype

Genotype
MGI:3815444

• Allelic Composition: Ighm^tm1Msn/Ighm^tm1Msn
• Genetic Background: B6.129S-Ighm^tm1Msn

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

immune system

decreased follicular B cell number ( J:80656 )

• there is a 25% reduction in the number of follicular B cells

increased marginal zone B cell number ( J:80656 )

• there is a 2.5-fold increase in the number of marginal zone CD21^highCD23^low B cells

• a larger IgM^brightIgD^dull MZ area on the periphery of the follicle exists compared with wild-type controls

• a reduction in MZ B cell number is observed after the administration of polyclonal IgM

abnormal B-1a B cell morphology ( J:80656 )

• there is a doubling in the number of CD5⁺B cells found in the spleen

• increased B-1a B cells are also found in the peritoneum

abnormal splenic cell ratio ( J:80656 )

• the ratio of marginal zone B cell numbers to follicular B cell numbers (MZ:FO) is more than double that of wild-type mice at 4 months of age

• at 12 months of age the MZ:FO ratio is not as elevated but is still significantly higher than age-matched controls

• this ratio can be normalized by administration of polyclonal, but not monoclonal, IgM

decreased IgM level ( J:80656 )

• serum levels of IgM are undetectable in these mice

hematopoietic system

decreased follicular B cell number ( J:80656 )

• there is a 25% reduction in the number of follicular B cells

increased marginal zone B cell number ( J:80656 )

• there is a 2.5-fold increase in the number of marginal zone CD21^highCD23^low B cells

• a larger IgM^brightIgD^dull MZ area on the periphery of the follicle exists compared with wild-type controls

• a reduction in MZ B cell number is observed after the administration of polyclonal IgM

abnormal B-1a B cell morphology ( J:80656 )

• there is a doubling in the number of CD5⁺B cells found in the spleen

• increased B-1a B cells are also found in the peritoneum

abnormal splenic cell ratio ( J:80656 )

• the ratio of marginal zone B cell numbers to follicular B cell numbers (MZ:FO) is more than double that of wild-type mice at 4 months of age

• at 12 months of age the MZ:FO ratio is not as elevated but is still significantly higher than age-matched controls

• this ratio can be normalized by administration of polyclonal, but not monoclonal, IgM

decreased IgM level ( J:80656 )

• serum levels of IgM are undetectable in these mice