Group B patients who received treatment with rituximab completed the treatment period through Week 36 and, if qualified, had the option of entering the optional extension re-treatment period. Patients who did not qualify for or who did not choose to receive the optional extension re-treatment entered the approximately 1-year safety follow-up period. After the safety follow-up period, patients who remained peripherally CD19-positive B-cell depleted entered the B-cell follow-up period where they were followed every 12 weeks until their peripheral CD19-positive B cells returned to baseline values or the lower limit of normal, whichever was lower.