title: Activated human NK cells can stimulate resting B cells to secrete immunoglobulin.
abstract: In addition to their cytotoxic function, NK cells can either suppress or enhance Ab production. Upon activation, NK cells generally amplify Ig secretion by activated B cells. We now report that activated NK cells prepared from human peripheral blood can induce resting B cells to produce IgM and IgG. This was demonstrated by adding IL-2 or pokeweed mitogen to purified NK cells and B cells. The addition of IL-2-activated NK cells to B cells also had this effect. The responding B cells did not require activation. Moreover, following fractionation of B cells on Percoll gradients, responsive B cells were found in the high density as well as the low density fractions. The NK cell stimulatory effect was a two-step process. The first step induced B cells to respond to soluble mediators and was mediated by unstimulated NK cells, but not CD4 nor CD8 T cells. Physical contact between NK cells and B cells was required, and mAbs to CD11a and CD54 blocked this interaction. The second step was the production of as yet unidentified cytokine(s) by activated NK cells. These direct T cell-independent stimulatory effects of NK cells on B cells may be important in autoimmune and other chronic inflammatory diseases in which the suppressive effects of NK cells may be blocked.
authors.affiliation: Department of Medicine, University of Southern California, School of Medicine, Los Angeles 90033, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Gray
authors.forename: D A
authors.initials: DA
authors.lastname: Horwitz
mesh_terms: D000328:Adult; D001402:B-Lymphocytes / Q000276:immunology*; D002448:Cell Adhesion / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis; D007136:Immunoglobulins / Q000096:biosynthesis*; D007376:Interleukin-2 / Q000096:biosynthesis / Q000502:physiology; D015979:Killer Cells, Lymphokine-Activated / Q000276:immunology*; D011043:Pokeweed Mitogens / Q000494:pharmacology
chemical_list: D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007136:Immunoglobulins; D007376:Interleukin-2; D011043:Pokeweed Mitogens