A method of making a population of human immune effector cells (e.g., T cells) that can be engineered to express a chimeric antigen receptor, the method comprising: a) providing a frozen input sample, e.g. a plasma apheresis sample, comprising immune effector cells, wherein the input sample is from a patient that has a disease associated with a tumor antigen, further wherein the disease associated with a tumor antigen is cancer or an autoimmune disease, b) thawing the frozen input sample, to produce a thawed sample, and c) performing elutriation on the thawed sample and collecting immune effector cells, thereby producing an output sample comprising immune effector cells that are suitable for expression of a CAR, optionally wherein: (i) the method comprises a step of adjusting the viscosity of the thawed sample, e.g., by adding an isotonic solution, e.g., PBS, to the thawed sample; and/or (ii) the elutriation is performed: 1) using a flow rate of from about 30-82 mL/min or 50-80 mL/min and/or the collection volume is about 250-1250 mL or 300-1000 mL for each fraction, e.g., the elutriation is performed using a flow rate of about 30, 40, 50, 60, 70, 72, or 82 mL/min, e.g., about 70 or 72 mL/min; 2) using a collection volume of about 250, 400, 500, 900, or 975 mL, e.g., about 400 or 975 mL; and/or 3) at about 2400 rpm. a) providing a frozen input sample, e.g. a plasma apheresis sample, comprising immune effector cells, wherein the input sample is from a patient that has a disease associated with a tumor antigen, further wherein the disease associated with a tumor antigen is cancer or an autoimmune disease, b) thawing the frozen input sample, to produce a thawed sample, and c) performing elutriation on the thawed sample and collecting immune effector cells, thereby producing an output sample comprising immune effector cells that are suitable for expression of a CAR, optionally wherein: (i) the method comprises a step of adjusting the viscosity of the thawed sample, e.g., by adding an isotonic solution, e.g., PBS, to the thawed sample; and/or (ii) the elutriation is performed: 1) using a flow rate of from about 30-82 mL/min or 50-80 mL/min and/or the collection volume is about 250-1250 mL or 300-1000 mL for each fraction, e.g., the elutriation is performed using a flow rate of about 30, 40, 50, 60, 70, 72, or 82 mL/min, e.g., about 70 or 72 mL/min; 2) using a collection volume of about 250, 400, 500, 900, or 975 mL, e.g., about 400 or 975 mL; and/or 3) at about 2400 rpm. (i) the method comprises a step of adjusting the viscosity of the thawed sample, e.g., by adding an isotonic solution, e.g., PBS, to the thawed sample; and/or (ii) the elutriation is performed: 1) using a flow rate of from about 30-82 mL/min or 50-80 mL/min and/or the collection volume is about 250-1250 mL or 300-1000 mL for each fraction, e.g., the elutriation is performed using a flow rate of about 30, 40, 50, 60, 70, 72, or 82 mL/min, e.g., about 70 or 72 mL/min; 2) using a collection volume of about 250, 400, 500, 900, or 975 mL, e.g., about 400 or 975 mL; and/or 3) at about 2400 rpm. 1) using a flow rate of from about 30-82 mL/min or 50-80 mL/min and/or the collection volume is about 250-1250 mL or 300-1000 mL for each fraction, e.g., the elutriation is performed using a flow rate of about 30, 40, 50, 60, 70, 72, or 82 mL/min, e.g., about 70 or 72 mL/min; 2) using a collection volume of about 250, 400, 500, 900, or 975 mL, e.g., about 400 or 975 mL; and/or 3) at about 2400 rpm.