Repeated immunizations with PC-KLH induced B cell differentiation in BLT mouse peripheral blood towards mature phenotypes and increased plasma antigen-specific IgM.

<p>(<b>A</b>) Immunization schedule. (<b>B–E</b>) The B cell populations in the PB of BLT mice (n = 7) were characterized before, during and after repeated PC-KLH immunizations. Representative flow cytometry analyses for CD27 and IgD expression on PB B cells (B) and longitudinal analysis of B cell populations (C) are shown. Similarly, (D–E) depict representative flow cytometry and longitudinal data regarding CD38 and IgD expression of PB B cells. (<b>F</b>) The percentage of CD38⁺⁺IgD^neg B cells that also express CD27 was calculated pre- and post-immunization to determine the contribution of atypical switched memory B cells to the CD27^negIgD^neg population in (B). (<b>G</b>) Plasma levels of antigen-specific IgM and IgG were measured longitudinally throughout the course of repeated PC-KLH immunizations (n = 7).