Patients receive BL22 immunotoxin IV over 30 minutes on days 1, 3, and 5 OR on days 1, 3, 5, 7, 9, and 11. Treatment repeats every 21 days for up to 6 courses in the absence of disease progression or unacceptable toxicity. Patients who achieve a complete response (CR) or unconfirmed CR (CRu) receive 2 additional courses beyond CR or CRu for a maximum of 6 courses.