title: Intracellular multiplication of Legionella pneumophila in HL-60 cells differentiated by 1,25-dihydroxyvitamin D3 and the effect of interferon gamma.
abstract: We examined leukemic cells, HL-60, an acute promyelocytic leukemia cell line, after differentiation induced by 1,25-dihydroxyvitamin D3 (D3) and retinoic acid (A) for infection of Legionella pneumophila, the etiologic agent of Legionnaires' disease. We investigated the effect of interferon gamma (IFN-gamma) on the differentiated cells and on the intracellular growth of the bacteria. An examination of morphological and antigenic changes in the cells was also included in the study. After 4-day incubation with 10(-6)M D3 or A, the HL-60 cells differentiated into monocyte-like (D3-HL-60) or mature granulocyte-like (A-HL-60) cells, respectively. They were then infected with L. pneumophila. Intracellular multiplication of the bacteria was evident in D3-HL-60 cells but not in HL-60 or A-HL-60 cells. D3-HL-60 cells required a 24-h infection time for the intracellular growth of L. pneumophila. D3-HL-60 cells activated with human recombinant IFN-gamma for 1-24 h (gamma-IFN-D3-HL-60 cells) before infection markedly inhibited L. pneumophila multiplication, the effect of IFN-gamma being dose dependent. Surface marker analysis was carried out in HL-60, D3-HL-60, and gamma-IFN-D3-HL-60 cells. On D3-HL-60 cells, CD11b, CD11c, CD14, and CD35 antigen increased, whereas CD71 and HLA-DR antigen decreased. This finding suggested that HL-60 cells differentiated into monocyte-like cells; the acquisition of the complement receptors, CD11b(CR3) and CD35(CR1), seemed to be important for phagocytosis and for the subsequent intracellular multiplication of L. pneumophila. The gamma-IFN-D3-HL-60 cells showed an increase of CD16, CD36, CD71, and HLA-DR antigen, suggesting that they were in an activated state. Our study indicated, first, that D3 can induce human leukemic cells to differentiate into functional monocyte-macrophage-like cells that can support the intracellular multiplication of L. pneumophila and, second, that these differentiated leukemic cells can be activated by IFN-gamma to markedly inhibit bacterial growth.
authors.affiliation: Department of Internal Medicine and Microbiology, Saga Medical School, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: Y
authors.initials: Y
authors.lastname: Shimamoto
authors.forename: S
authors.initials: S
authors.lastname: Yoshida
authors.forename: K
authors.initials: K
authors.lastname: Suga
authors.forename: Y
authors.initials: Y
authors.lastname: Mizuguchi
authors.forename: O
authors.initials: O
authors.lastname: Kohashi
authors.forename: M
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis; D015703:Antigens, CD / Q000032:analysis; D000951:Antigens, Neoplasm / Q000032:analysis; D002117:Calcitriol / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D006168:Guinea Pigs; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D007424:Intracellular Fluid / Q000382:microbiology; D016952:Legionella pneumophila / Q000187:drug effects / Q000254:growth & development* / Q000276:immunology; D007877:Legionnaires' Disease / Q000188:drug therapy / Q000473:pathology; D007942:Leukemia, Experimental / Q000382:microbiology / Q000473:pathology; D015473:Leukemia, Promyelocytic, Acute / Q000276:immunology / Q000382:microbiology* / Q000473:pathology; D008262:Macrophage Activation; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D011994:Recombinant Proteins; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D000942:Antigens, Bacterial; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D011994:Recombinant Proteins; D014212:Tretinoin; D007371:Interferon-gamma; D002117:Calcitriol