Repeated immunizations with PC-KLH induced B cell differentiation in BLT mouse tissues towards mature phenotypes.

<p>(<b>A–B</b>) B cell populations in the BM, spleen, LN, liver and lungs were characterized in naïve and immunized BLT mice. CD27 and IgD (A) (naïve, n = 5; immunized, n = 7 for all tissues; <i>t</i>-tests) and CD38 and IgD (C) (naïve, n = 5; immunized, n = 7; <i>t</i>-tests) co-expression patterns revealed increased levels of CD19⁺ cells exhibiting mature phenotypes throughout the body following the repeated PC-KLH immunizations. (<b>C</b>) The percentage of CD38⁺⁺IgD^neg B cells that also express CD27 was calculated in naive BLT mice and PC-KLH immunized BLT mice to determine the contribution of atypical switched memory B cells to the CD27^negIgD^neg populations from each tissue in (A). (<b>D</b>) Sections from spleen (left) and lymph node (right) of PC-KLH immunized BLT mice analyzed for lymphoid architecture via H&E staining. Scale bars = 50 µm in all images. Boxes indicate the areas that are shown at higher magnification in the images below. * indicates a p value less than 0.05. ** indicates a p value less than 0.01. *** indicates a p value less than 0.001. Comprehensive statistical analyses are presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0108663#pone-0108663-t003" target="_blank">Table 3</a>.