Repair of immunoglobulin response in B cell line (JK32.1) originating from immunodeficient patient via implantation of functional plasma membranes

Abstract Human-human B cell hybridoma JK32.1, constructed from B lymphocytes of a common variable immunodeficient patient and nonsecreting cell line, retains the defects of B cell immunodeficiency. Efforts to clarify whether the defect is located within the plasma membranes of this cell line were carried out by implanting them with plasma membrane fraction derived from normal functional cells via intact noninfectious Sendai virus. The implanted cells were activated with various mitogens and their Ig responses and isotype switching were examined. Restoration of IgM secretion was achieved in the implanted JK32.1 cells following stimulation with SAC, PWM, or retinoic acid. Augmented IgM response was also obtained in the implanted cells treated with retinoic acid and lipopolysaccharide (LPS) despite their unresponsiveness to LPS alone. No IgG or IgA response could be detected in the implanted JK32.1 cells. These data suggest that this immunodeficient cell line possesses at least two different malfunctions, one located within the plasma membrane moiety of the cells and the other located within the cytoplasmic and/or nucleic components. The plasma membrane moiety defect can be repaired temporarily by delivering proper signals via the implanted plasma membranes. However, this manipulation of the cells could not overcome the intrinsic defect of the cells which blocks isotype switching and secretion of IgG, IgE, and IgA antibodies.