Serum immunoglobulin and antigen-specific antibody titers following CAR19. (A) Individual patient time courses showing recovery of serum IgG levels post–axi-cel infusion, stratified by whether patients received IVIG. The bold (Non-IVIG and IVIG) trend lines represents locally weighted scatterplot smoothing. Enzyme-linked immunosorbent assays were performed to detect antigen-specific IgG antibodies against Epstein-Barr virus (EBV) nuclear antigen 1 protein (EBNA1) (B), tetanus toxoid protein (C), and varicella-zoster virus (VZV) glycoprotein E (gpE) (D). Individual patient values relative to their pretreatment baseline are shown by the markers at each time point, with the bold (Non-IVIG and IVIG) trend lines connecting the geometric mean, stratified by whether patients received IVIG. P values shown were obtained by unpaired Student t tests between groups and Kruskal-Wallis tests within groups where each time point was treated as an independent group; both were adjusted for multiple comparisons using the Holm-Šídák method.