B-cell repopulation after rituximab infusion in ITP patients with initial response > 1 year. Solid lines denote patients who relapsed after 1 year (n = 14), and dashed lines denote patients responding over 2.5 years without relapse (n = 18). Linear functions describing the mean rate of B-cell return in individual patients were used to calculate the average linear rate of B-cell return in those who relapsed (solid line) and in responders > 2.5 years (dashed line); dotted lines represent the SEM of these linear functions (P < .05). Curved solid and dashed trendlines represent the spline fit of the average number of CD19+ B cells (×109/L) in patients who relapsed after 1 year and those responding over 2.5 years (measured at 50-day intervals), respectively; curved trendlines were not used for statistical determinations.
