Natural killer cells can enhance the proliferative responses of B lymphocytes.
In addition to lytic activity against malignant and virally transformed target cells, recent evidence has suggested that natural killer (NK) cells can modulate immune activities such as the suppression of B cell responses through noncytotoxic means. Using human B cells and highly purified autologous NK cells, we have demonstrated that NK cells can substantially augment the proliferative responses of B cells stimulated with the surface immunoglobulin crosslinking agents anti-IgM or Staphylococcus aureus Cowan strain I (SAC). This "enhancer" activity of NK cells was quite potent and was observed at an NK:B cell ratio as low as 0.05. Peak blastogenic responses of B cells cocultured with NK cells in the presence of B cell activators were observed at 2-3 days, similar to the responses of B cells in the absence of NK cells. Using the inhibitor of DNA synthesis mitomycin C, we determined that B cells and not NK cells were proliferating in cocultures of these lymphocytes stimulated with SAC. Activated B cells neither prevented the lysis of the isotope-labeled NK-sensitive target cell line K562 nor formed conjugates with NK cells, suggesting that cell contact was not a prerequisite for the effect. These studies have further expanded the functional repertoire of NK cells to include enhancer as well as suppressor and lytic activities.
Katz
P
P
Department of Medicine, Georgetown University School of Medicine, Washington, D.C. 20007.
Whalen
G
G
Cupps
T R
TR
Mitchell
S R
SR
Evans
M
M
D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D000937:Antigen-Antibody Reactions; D001402:B-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D004306:Dose-Response Relationship, Immunologic; D006801:Humans; D007148:Immunoglobulin mu-Chains / Q000276:immunology; D066298:In Vitro Techniques; D007694:Killer Cells, Natural / Q000276:immunology*; D008213:Lymphocyte Activation; D011971:Receptors, Immunologic / Q000276:immunology
D000888:Antibodies, Anti-Idiotypic; D007148:Immunoglobulin mu-Chains; D011971:Receptors, Immunologic