<p>Serum IgG (A), IgA (B) and IgM (C) levels in the year before Ig-replacement are shown for the primary (n = 58) and secondary groups (n = 27). Each symbol represents the mean value over the year for one subject and the bars represent the group median. The frequency of switched memory B cells (CD19<sup>+</sup>CD27<sup>+</sup>IgD<sup>−</sup>IgM<sup>−</sup>) as a proportion of peripheral blood B cells is shown for the primary (n = 50) and secondary (n = 10) groups (D). Dotted lines indicate the normal reference ranges for each. Data in panels A–C were analysed by a two-tailed unequal variance t-test and data in panel D were analysed by a two-tailed Mann-Whitney test; * p<0.05, ** p<0.01; n.s. non-significant.</p
