It is an object of the present invention to provide a method for efficiently producing a B cell population comprising B cells that recognize a specific antigen. According to the present invention, provided is a method for producing a B cell population, comprising: a step (c) of culturing a cell population comprising B cells together with a specific antigen in the absence of IL-21, in the absence of IL-4, and in the presence of a cytokine other than IL-21 and IL-4, while giving stimulation mediated by CD40 and a BAFF receptor to the cells; and a step (d) of culturing the cell population comprising B cells, while giving stimulation mediated by has to the cells, so as to obtain a B cell population comprising B cells that recognize the specific antigen.

The disclosure provides methods of making CAR-expressing immune effector cells (e.g., T cells, or NK cells), and compositions and reaction mixtures comprising the same. The disclosure further provides methods of using said CAR-expressing immune effector cells.

It is an object of the present invention to provide a method for efficiently producing a B cell population comprising B cells that recognize a specific antigen. According to the present invention, provided is a method for producing a B cell population, comprising: a step (c) of culturing a cell population comprising B cells together with a specific antigen in the absence of IL-21, in the absence of IL-4, and in the presence of a cytokine other than IL-21 and IL-4, while giving stimulation mediated by CD40 and a BAFF receptor to the cells; and a step (d) of culturing the cell population comprising B cells, while giving stimulation mediated by has to the cells, so as to obtain a B cell population comprising B cells that recognize the specific antigen.

The disclosure provides methods of making CAR-expressing immune effector cells (e.g., T cells, or NK cells), and compositions and reaction mixtures comprising the same. The disclosure further provides methods of using said CAR-expressing immune effector cells.