Human CD56bright and CD56dim natural killer cell subsets respond differentially to direct stimulation with Mycobacterium bovis bacillus Calmette-Guérin.
Mycobacterium bovis bacillus Calmette-Guérin (BCG) is capable of directly stimulating several effector functions of human natural killer (NK) cells in the absence of interleukin-12 and professional antigen presenting cells. To assess the contribution of two main human NK-cell subsets (CD56(dim) and CD56(bright)) to the overall in vitro NK-cell response to BCG, peripheral blood mononuclear cells depleted of nylon wool-adherent cells or purified NK cells were stimulated with live BCG. By combining intranuclear bromodeoxyuridine (BrdU) staining and analysis of CD56 marker intensity, statistically higher percentages of BrdU(+) cells were found among the CD56(bright) subset than the CD56(dim) subset after 6 days of stimulation with BCG. Similarly, evaluation of intracellular interferon-gamma (IFN-gamma) revealed that CD56(bright) cells were those mainly involved in IFN-gamma production in response to BCG. In contrast, the CD56(dim) subset contained higher levels of perforin and granzyme A, two key molecules for exocytosis-mediated cytotoxicity, than the CD56(bright) subset. Although 16-20-h stimulation with BCG did not substantially alter the expression of cytotoxic molecules by the two subsets, a decrease in perforin content was observed in the CD56(dim), but not in the CD56(bright) subset, following 4-h incubation with the NK-sensitive target K562 cell line. This decrease in perforin content correlated with the induction by BCG-stimulated NK cells, of early markers of apoptosis on target cells to a greater extent than unstimulated cells suggesting a major role for the CD56(dim) subset in cytotoxic activity in response to BCG. Taken together, these results demonstrate that CD56(bright) and CD56(dim) human NK-cell subsets exert different functional activities in response to a live bacterial pathogen.
Batoni
G
G
Dipartimento di Patologia Sperimentale, Biotecnologie Mediche, Infettivologia ed Epidemiologia, University of Pisa, Italy. batoni@biomed.unipi.it
Esin
S
S
Favilli
F
F
Pardini
M
M
Bottai
D
D
Maisetta
G
G
Florio
W
W
Campa
M
M
D000483:Alleles; D001500:BCG Vaccine / Q000276:immunology; D019002:CD56 Antigen / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic; D053804:Granzymes; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D008213:Lymphocyte Activation; D016131:Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics; D009163:Mycobacterium bovis / Q000276:immunology*; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012697:Serine Endopeptidases / Q000096:biosynthesis / Q000235:genetics
D001500:BCG Vaccine; D019002:CD56 Antigen; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D007371:Interferon-gamma; D053804:Granzymes; D012697:Serine Endopeptidases; C509212:GZMA protein, human