Induction of CD14 antigen on the surface of U937 cells by an interleukin-6 autocrine mechanism after culture with formalin-killed gram-negative bacteria.
In order to better understand the regulation of CD14 antigen on the surface of the monocyte-like cell line U937 in response to bacteria, the expression and regulation of CD14 antigen on these cells when cultured with formalin-killed bacteria were determined using the monoclonal antibody MY-4 and analyzed by means of the indirect immunofluorescence method. CD14 expression was induced on the U937 cells after about 48 hours of culture with all of the formalin-killed Gram-negative bacteria used in this study but with none of the Gram-positive bacteria. Maximum expression was obtained after culture with formalin-killed Salmonella enteritidis strain 116-54. Various cytokines such as interleukin-1 beta, interleukin-2, interleukin-6, interferon-gamma and tumor-necrosis factor-alpha were assayed in the culture supernatant of U937 cells cultured with or without formalin-killed Salmonella enteritidis 116-54 using an enzyme-immunoassay or radioimmunoassay system. The U937 cells were found to produce a large amount of interleukin-6 in response to formalin-killed Salmonella enteritidis 116-54. On the other hand, culture supernatant (referred to as conditioned medium) obtained from the U937 cells after 72 h of culture with formalin-killed Salmonella enteritidis 116-54 also induced strong expression of CD14 antigen 48 to 72 h later, and this was blocked by the addition of anti-human interleukin-6 antibody. These findings suggest that the expression of CD14 antigen on the surface of U937 cells cultured with formalin-killed Gram-negative bacteria is induced by interleukin-6 and can be explained on the basis of the autocrine mechanism of interleukin-6.
Ikewaki
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N
Department of Microbiology, Kitasato University School of Nursing, Sagamihara, Japan.
Inoko
H
H
D015703:Antigens, CD / Q000096:biosynthesis*; D015214:Antigens, Differentiation, Myelomonocytic / Q000096:biosynthesis*; D000951:Antigens, Neoplasm / Q000096:biosynthesis*; D005557:Formaldehyde; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism / Q000494:pharmacology*; D018950:Lipopolysaccharide Receptors; D016403:Lymphoma, Large B-Cell, Diffuse / Q000473:pathology; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D012477:Salmonella enteritidis; D014407:Tumor Cells, Cultured / Q000276:immunology / Q000378:metabolism
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D000951:Antigens, Neoplasm; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D009363:Neoplasm Proteins; D005557:Formaldehyde