Abstract: 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.

Abstract: A peptide complex including: a peptide; and a cell-membrane-permeability-imparting group introduced into the peptide, wherein the cell-membrane-permeability-imparting group includes a dendritic structure including four or more branches, and at least four branches of the four or more branches include basic functional groups at ends thereof.

Abstract: Novel cell-penetrating peptides are provided, which are excellent in cell membrane permeability. The cell-penetrating peptide or salt thereof according to the present invention is characterized in comprising the sequence represented by formula (I) or the formula (II) as follows: X-(A-B-C)l-(D)m-(Arg)n (Formula I) or X-(Arg)n-(D)m-(A-B-C)l (Formula II), wherein X is a physiologically active peptide, A, B and C are aliphatic amino acids, D is an arbitrary amino acid, l is an integer of 1 or more and 4 or less, m is an integer of 0 or more and 5 or less, when l is 1, n is an integer of 8 or more, when l is 2, n is an integer of 6 or more, when l is 3, n is an integer of 4 or more, when l is 4, n is an integer of 4 or more.

Abstract: A method for producing a transgenic cell, may include contacting, in vitro, (i) a virus comprising: a chimeric protein of an antibody-binding protein and a vesicular stomatitis virus G (VSV-G) protein; and a foreign gene, with (ii) a target cell and an antibody specific to the target cell, and/or a target cell comprising a membrane antibody, to infect the target cell with the virus.

Abstract: 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.

Abstract: A method for producing a transgenic cell, may include contacting, in vitro, (i) a virus comprising: a chimeric protein of an antibody-binding protein and a vesicular stomatitis virus G (VSV-G) protein; and a foreign gene, with (ii) a target cell and an antibody specific to the target cell, and/or a target cell comprising a membrane antibody, to infect the target cell with the virus.