Reconstitution of the humoral defects in SAP-deficient mice after immune challenge. (A) Quantification of baseline serum immunoglobulin levels by ELISA 12 weeks after reconstitution. Values for individual mice are shown as dots, and the mean of all values is represented by a horizontal line. (B) Quantification of NP-specific antibody production by ELISA at various time points after immunization with NP-CGG in control and reconstituted animals. (C) Detection of germinal center B cells by flow cytometry in splenic lymphocytes stained with anti-CD19 and anti-Gl7 antibodies. Values for individual mice are shown as dots, and the mean of all values is represented by a horizontal line. (D) Germinal center staining in splenic follicles of control and reconstituted mice 10 days after immunization using the germinal center B-cell marker peanut agglutinin (PNA). In addition to original magnification (×40) for all groups, original magnification (×100) of a single follicle to show degree of germinal center recovery is shown for WT and EFS-SAPeGFP mice.