Any condition which in the opinion of the attending physician or the Apheresis Unit staff contraindicates apheresis procedures, such as cardiovascular instability, severe anemia (hematocrit/hemoglobin below less than 26/8), in adequate venous access, and/or severe coagulation disorder. Patients with severe infection who have a hematocrit/hemoglobin below less than 26/8 and might benefit clinically from participation in this protocol may undergo apheresis at the discretion of the physician in charge of the Apheresis Unit. In that setting RBC transfusion may be used to raise the hematocrit/hemoglobin to a level safe for apheresis.