IgG S1 concentration and B cell numbers related to time after end of rituximab or HCT. (A) Patients with lymphoma after autologous HCT or after rituximab. (B) Multiple myeloma after autologous HCT. (C) Allogeneic HCT. Left panels: S1 IgG concentration with dotted lines specifying seroconversion (S1 IgG > 10 BAUs/mL) and sufficient S1 IgG concentration (≥300 BAUs/mL). Right panels: B-cell number with dotted lines at upper and lower limit of normal.