Rhodococcus equi infection of monocytes/macrophages from human immunodeficiency virus (HIV)-infected patients and healthy individuals: evaluation of intracellular killing and nitric oxide production.
Monocytes/macrophages from human immunodeficiency virus (HIV)-infected patients had a defect in their ability to kill Rhodococeus equi in vitro, as compared with healthy HIV-seronegative individuals. Virulent and avirulent R. equi strains isolated from humans and horses showed no significant intracellular replicative differences within both HIV-positive and -negative monocytes/macrophages. Infection with R. equi induced the production of nitric oxide (NO) by monocytes/macrophages from healthy individuals, but not by cells from HIV-positive patients. The NO formation was significantly inhibited by L-NG-monomethyl arginine and arginase. However. neither competitive inhibition of NO synthesis from L-arginine with L-NMMA nor depletion of arginine with arginase altered the killing activity of human monocytes/macrophages against R. equi, thus suggesting that L-arginine:NO pathway is not required for the intracellular antirhodococcal mechanisms of human monocytes/macrophages.
Vullo
V
V
Department of Infectious and Tropical Diseases, Policlinico Umberto I, La Sapienza University, Rome, Italy. vullo@caspur.it
Mastroianni
C M
CM
Lichtner
M
M
Mengoni
F
F
D'Agostino
C
C
Forcina
G
G
Corpolongo
A
A
Delia
S
S
D017088:AIDS-Related Opportunistic Infections / Q000276:immunology; D000193:Actinomycetales Infections / Q000276:immunology; D000818:Animals; D001119:Arginase / Q000494:pharmacology; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000187:drug effects / Q000502:physiology*; D015658:HIV Infections / Q000276:immunology*; D006736:Horses; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009573:Nitrites / Q000378:metabolism; D016929:Rhodococcus equi / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D019323:omega-N-Methylarginine / Q000494:pharmacology
D009573:Nitrites; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D001119:Arginase