All Phenotypes Igh<tm5.1Cgn> MGI Mouse

abnormal B cell differentiation ( J:88472 )

• homozygotes exhibit development of follicular and marginal zone B cells but not of B-1 cells

decreased immature B cell number ( J:88472 )

• homozygotes show a marked reduction in the immature B cell fraction (CD21^loCD24^hi) relative to wild-type controls

• homozygotes display a higher percentage of pro-B cells (CD19⁺CD43⁺) in the bone marrow relative to wild-type controls

• in homozygotes, the absolute numbers of splenic and lymph node B cells are only one-third to one-fourth of those in age-matched wild-type controls

abnormal mature B cell morphology ( J:88472 )

• the majority of mature B cells found in the spleen, lymph nodes and peritoneal cavity exhibit the follicular phenotype CD21^intCD23⁺CD22⁺CD5^-

• mature B cells express 2- to 3-fold more surface CD19 and slightly reduced surface CD22 and B220 relative to wild-type B cells

• surface expression of CD38, CD40, BAFF-R, CD180 and MHC class II molecules is similar to that of wild-type resting follicular B cells

• a subset of marginal zone B cells (CD21^hiCD23^loCD1d^hiCD38^hi) distinct from follicular and B-1 B cells is found in spleen

absent B-1 B cells ( J:88472 )

absent B-1a cells ( J:88472 )

• homozygotes lack CD5⁺ B-1 cells

absent B-1b cells ( J:88472 )

• homozygotes lack CD5^- B-1 cells

decreased marginal zone B cell number ( J:88472 )

• in homozygotes, the absolute number of marginal zone B cells is only modestly reduced relative to that in wild-type controls

absent spleen germinal center ( J:88472 )

• following immunization with sheep red blood cells or with alumprecipitated nitrophenylacetyl chicken gamma globulin, homozygotes fail to exhibit splenic germinal center B cells (CD19⁺PNA^hi), unlike wild-type controls

abnormal B cell activation ( J:88472 )

• peripheral B cells lack signs of cell activation, as determined by cell size and increased surface expression of CD69, CD86 and MHC class II molecules

abnormal gut-associated lymphoid tissue morphology ( J:88472 )

• unexpectedly, non-immunized homozygotes exhibit spontaneous germinal center formation in gut-associated lymphoid tissue (GALT), indicating that B cell entry into GALT germinal centers can occur in the absence of antigen recognition through the B cell receptor

abnormal Peyer's patch germinal center morphology ( J:88472 )

• unexpectedly, non-immunized homozygotes exhibit spontaneous germinal center formation in Peyer's patches

abnormal lymph node germinal center morphology ( J:88472 )

• unexpectedly, non-immunized homozygotes exhibit spontaneous germinal center formation in mesenteric lymph nodes (MLNs)