With the invention of the Continuous Flow Cell Centrifuge methods are now available for obtaining large quantities of human leukocytes for biochemical, therapeutic and immunologic investigations. The purposes of this investigation are to study the following: 1) By means of a controlled study, determine the effects of corticosteroids on the yield and function of granulocytes from normal donors; 2) Assessment of the role of granulocyte transfusing in the treatment of infections in agranulocytic patients by a randomized study; 3) The effect of leukapheresis on the kinetics of granulopoiesis in normal and leukemic patients by quantitating changes in humoral regulators of granulopoiesis by means of an in vitro assay; 4) Assessment (by a controlled study) of the effects of transfused lymphocytes on the recipients of granulocyte transfusions by monitoring graft vs. host reactions and measuring the adoptive transfer of specific cellular and humoral immune responses; 5) Immunotherapeutic methods of treating leukemic patients by auto- immunization with leukemic cells rendered more antigenic by alterations of the cell membrane with and without concurrent BCG immunization; and 6) Detection of human anti-leukemic antibody by micro-titer complement- fixation technique.