Patients receive recombinant BL22 immunotoxin IV over 30 minutes on days 1, 3, and 5. Treatment repeats ≥ every 27 days for up to 6 courses in the absence of neutralizing antibodies to BL22 or PE38, disease progression, or unacceptable toxicity. Patients achieving a complete response (CR) receive 2 additional courses beyond CR. Patients who relapse from a CR lasting ≥ 6 months may receive additional courses.