Figure 5Flow cytometric analysis of plasma cells from the spleen (A) and bone marrow (B) of Prdm1ihCd2/+ and wild-type (WT) mice under steady-state conditions. Representative flow cytometric data are shown for 12-month-old mice (left), while bar graphs present absolute numbers of plasma cells for Prdm1ihCd2/+ (red) and wild-type (gray) mice at the age of 2, 4 and 12 months (right)T cell-dependent immune responses. Prdm1ihCd2/+ (red dots) and wild-type (gray dots) mice at the age of 2 months were immunized with NP-KLH (in alum) and analyzed at day 14 after immunization by ELISPOT assa The number of anti-NP-IgM antibody-secreting cells (ASCs) in the spleen was determined by ELISPOT assay (C) using NP24-BSA-coated plates for detecting cells secreting total anti-NP-IgM antibodies. ELISPOT results are shown as representative pictures (left) or absolute ASC numbers (right) (C) Dot plots display the serum immunoglobulin titers of Prdm1ihCd2/+ (red dots) and wild-type (gray dots) mice NP-specific IgG1 concentrations (μg/ml) were determined relative to a standard NP-binding IgG1 antibodyT cell-dependent immune responses. Prdm1ihCd2/+ (red dots) and wild-type (gray dots) mice at the age of 2 months were immunized with NP-KLH (in alum) and analyzed at day 14 after immunization b ELISA The serum titers of anti-NP-specific IgM, IgG1 and IgG2b antibodies were analyzed by ELISA using NP7-BSA- or NP24-BSA-coated plates for detecting high-affinity IgG1 or total IgM, IgG1 and IgG2b antibodies, respectivel Dot plots display the serum immunoglobulin titers of Prdm1ihCd2/+ (red dots) and wild-type (gray dots) mice. NP-specific IgG1 concentrations (μg/ml) were determined relative to a standard NP-binding IgG1 antibody, whereas IgM and IgG2b amounts are indicated as relative units (RU) by setting the WT data to 1Flow cytometric analysis of splenic GC B cells in Prdm1ihCd2/+ (red) and wild-type (gray) mice (at the age of 2 months) at day 14 after NP-KLH immunization. Bar graphs display absolute numbers of GC B cells detected in the spleen of both genotype The absence of Bcl6 expression in non-GC B cells (black) is shown as referenceFlow cytometric analysis of splenic GC B cells in Prdm1ihCd2/+ (red) and wild-type (gray) mice (at the age of 2 months) at day 14 after NP-KLH immunization Cell surface expression of hCD2 and intracellular staining of Bcl6 are shown for Prdm1ihCd2/+ (red) and wild-type (gray) GC B cell The absence of Bcl6 expression in non-GC B cells (black) is shown as referenceFlow cytometric analysi in Prdm1ihCd2/+ (red) and wild-type (gray) mice (at the age of 2 months) at day 14 after NP-KLH immunization Flow cytometric analysis of splenic TFH cell Bar graphs indicate absolute numbers of TFH cell in hCD2lo (black) and hCD2hi (blue) Prdm1ihCd2/+ as well as wild-type (gray) TFH cellsFlow cytometric analysi in Prdm1ihCd2/+ (red) and wild-type (gray) mice (at the age of 2 months) at day 14 after NP-KLH immunization Flow cytometric analysis of splenic TFH cell histograms display cell surface expression of hCD2 and intracellular staining of Bcl6 (H) in hCD2lo (black) and hCD2hi (blue) Prdm1ihCd2/+ as well as wild-type (gray) TFH cellsEfficient in vitro plasmablast differentiation of immature B cells. Immature B cells sorted from the bone marrow of Prdm1ihCd2/+ (red) and wild-type (gray) mice were stimulated with CpG oligodeoxynucleotides or LPS for 60 hours followed by flow cytometric analysis of CD138+CD22lo plasmablasts (PB). Bar graphs (right) summarize the plasmablast data of the CpG and LPS stimulation experimentsELISA detection of Igκ-containing antibodies in the supernatants of immature B cells at 60 h of CpG or LPS stimulation