- Individuals at least 18 years of age who have been diagnosed with MBL, CLL, SLL, or MCL, but who have not been taking certain agents (Viagra, Levitra, Cialis, or other PDE-inhibitors, prednisone, cyclosporin-A, rapamycin, or other immunosuppressive agents, more than 2 cups of green tea daily, or Celebrex) for 4 weeks prior to enrollment in the study.