• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Logo of jcinvestThe Journal of Clinical InvestigationCurrent IssueArchiveSubscriptionAbout the Journal
J Clin Invest. Sep 15, 1997; 100(6): 1640–1646.
PMCID: PMC508346

Chloroquine induces human mononuclear phagocytes to inhibit and kill Cryptococcus neoformans by a mechanism independent of iron deprivation.


Infections due to Cryptococcus neoformans are common in AIDS patients. We investigated the effect of chloroquine, which raises the pH of phagolysosomes, on the anticryptococcal activity of mononuclear phagocytes. C. neoformans multiplied within monocyte-derived macrophages (MDM) in the absence of chloroquine but were killed with the addition of chloroquine. Ammonium chloride was also beneficial, suggesting that effects were mediated by alkalinizing the phagolysosome. Chloroquine inhibits growth of other intracellular pathogens by limiting iron availability. However, chloroquine-induced augmentation of MDM anticryptococcal activity was unaffected by iron nitriloacetate, demonstrating that chloroquine worked by a mechanism independent of iron deprivation. There was an inverse correlation between growth of C. neoformans in cell-free media and pH, suggesting that some of the effect of chloroquine on the anticryptococcal activity of MDM could be explained by relatively poor growth at higher pH. Chloroquine enhanced MDM anticryptococcal activity against all tested cryptococcal strains except for one large-capsule strain which was not phagocytosed. Positive effects of chloroquine were also seen in monocytes from both HIV-infected and -uninfected donors. Finally, chloroquine was therapeutic in experimental cryptococcosis in outbred and severe combined immunodeficient mice. Thus, chloroquine enhances the activity of mononuclear phagocytes against C. neoformans by iron-independent, pH-dependent mechanisms and is therapeutic in murine models of cryptococcosis. Chloroquine might have clinical utility for the prophylaxis and treatment of human cryptococcosis.

Full Text

The Full Text of this article is available as a PDF (215K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Powderly WG. Cryptococcal meningitis and AIDS. Clin Infect Dis. 1993 Nov;17(5):837–842. [PubMed]
  • Levitz SM. The ecology of Cryptococcus neoformans and the epidemiology of cryptococcosis. Rev Infect Dis. 1991 Nov-Dec;13(6):1163–1169. [PubMed]
  • Byrd TF, Horwitz MA. Chloroquine inhibits the intracellular multiplication of Legionella pneumophila by limiting the availability of iron. A potential new mechanism for the therapeutic effect of chloroquine against intracellular pathogens. J Clin Invest. 1991 Jul;88(1):351–357. [PMC free article] [PubMed]
  • Newman SL, Gootee L, Brunner G, Deepe GS., Jr Chloroquine induces human macrophage killing of Histoplasma capsulatum by limiting the availability of intracellular iron and is therapeutic in a murine model of histoplasmosis. J Clin Invest. 1994 Apr;93(4):1422–1429. [PMC free article] [PubMed]
  • Fortier AH, Leiby DA, Narayanan RB, Asafoadjei E, Crawford RM, Nacy CA, Meltzer MS. Growth of Francisella tularensis LVS in macrophages: the acidic intracellular compartment provides essential iron required for growth. Infect Immun. 1995 Apr;63(4):1478–1483. [PMC free article] [PubMed]
  • Dautry-Varsat A, Ciechanover A, Lodish HF. pH and the recycling of transferrin during receptor-mediated endocytosis. Proc Natl Acad Sci U S A. 1983 Apr;80(8):2258–2262. [PMC free article] [PubMed]
  • Starke PE, Gilbertson JD, Farber JL. Lysosomal origin of the ferric iron required for cell killing by hydrogen peroxide. Biochem Biophys Res Commun. 1985 Dec 17;133(2):371–379. [PubMed]
  • Sibille JC, Kondo H, Aisen P. Uptake of ferritin and iron bound to ferritin by rat hepatocytes: modulation by apotransferrin, iron chelators and chloroquine. Biochim Biophys Acta. 1989 Feb 9;1010(2):204–209. [PubMed]
  • Sibille JC, Ciriolo M, Kondo H, Crichton RR, Aisen P. Subcellular localization of ferritin and iron taken up by rat hepatocytes. Biochem J. 1989 Sep 1;262(2):685–688. [PMC free article] [PubMed]
  • Bates GW, Wernicke J. The kinetics and mechanism of iron(3) exchange between chelates and transferrin. IV. The reaction of transferrin with iron(3) nitrilotriacetate. J Biol Chem. 1971 Jun 10;246(11):3679–3685. [PubMed]
  • Olakanmi O, Stokes JB, Britigan BE. Acquisition of iron bound to low molecular weight chelates by human monocyte-derived macrophages. J Immunol. 1994 Sep 15;153(6):2691–2703. [PubMed]
  • Levitz SM, Tabuni A, Kornfeld H, Reardon CC, Golenbock DT. Production of tumor necrosis factor alpha in human leukocytes stimulated by Cryptococcus neoformans. Infect Immun. 1994 May;62(5):1975–1981. [PMC free article] [PubMed]
  • Miller MF, Mitchell TG. Killing of Cryptococcus neoformans strains by human neutrophils and monocytes. Infect Immun. 1991 Jan;59(1):24–28. [PMC free article] [PubMed]
  • Levitz SM, North EA, Jiang Y, Nong SH, Kornfeld H, Harrison TS. Variables affecting production of monocyte chemotactic factor 1 from human leukocytes stimulated with Cryptococcus neoformans. Infect Immun. 1997 Mar;65(3):903–908. [PMC free article] [PubMed]
  • Harrison TS, Levitz SM. Role of IL-12 in peripheral blood mononuclear cell responses to fungi in persons with and without HIV infection. J Immunol. 1996 Jun 1;156(11):4492–4497. [PubMed]
  • Harrison TS, Kornfeld H, Levitz SM. The effect of infection with human immunodeficiency virus on the anticryptococcal activity of lymphocytes and monocytes. J Infect Dis. 1995 Sep;172(3):665–671. [PubMed]
  • Levitz SM. Activation of human peripheral blood mononuclear cells by interleukin-2 and granulocyte-macrophage colony-stimulating factor to inhibit Cryptococcus neoformans. Infect Immun. 1991 Oct;59(10):3393–3397. [PMC free article] [PubMed]
  • Levitz SM, Tabuni A. Binding of Cryptococcus neoformans by human cultured macrophages. Requirements for multiple complement receptors and actin. J Clin Invest. 1991 Feb;87(2):528–535. [PMC free article] [PubMed]
  • Levitz SM, Tabuni A, Kozel TR, MacGill RS, Ingalls RR, Golenbock DT. Binding of Cryptococcus neoformans to heterologously expressed human complement receptors. Infect Immun. 1997 Mar;65(3):931–935. [PMC free article] [PubMed]
  • Clemons KV, Azzi R, Stevens DA. Experimental systemic cryptococcosis in SCID mice. J Med Vet Mycol. 1996 Sep-Oct;34(5):331–335. [PubMed]
  • Levitz SM, Farrell TP. Growth inhibition of Cryptococcus neoformans by cultured human monocytes: role of the capsule, opsonins, the culture surface, and cytokines. Infect Immun. 1990 May;58(5):1201–1209. [PMC free article] [PubMed]
  • Diamond RD, Bennett JE. Growth of Cryptococcus neoformans within human macrophages in vitro. Infect Immun. 1973 Feb;7(2):231–236. [PMC free article] [PubMed]
  • Wang Y, Casadevall A. Susceptibility of melanized and nonmelanized Cryptococcus neoformans to nitrogen- and oxygen-derived oxidants. Infect Immun. 1994 Jul;62(7):3004–3007. [PMC free article] [PubMed]
  • Krogstad DJ, Schlesinger PH. Acid-vesicle function, intracellular pathogens, and the action of chloroquine against Plasmodium falciparum. N Engl J Med. 1987 Aug 27;317(9):542–549. [PubMed]
  • Kozel TR, Pfrommer GS, Guerlain AS, Highison BA, Highison GJ. Strain variation in phagocytosis of Cryptococcus neoformans: dissociation of susceptibility to phagocytosis from activation and binding of opsonic fragments of C3. Infect Immun. 1988 Nov;56(11):2794–2800. [PMC free article] [PubMed]
  • Small JM, Mitchell TG, Wheat RW. Strain variation in composition and molecular size of the capsular polysaccharide of Cryptococcus neoformans serotype A. Infect Immun. 1986 Dec;54(3):735–741. [PMC free article] [PubMed]
  • Levitz SM. Macrophage-Cryptococcus interactions. Immunol Ser. 1994;60:533–543. [PubMed]
  • Jacobson ES, Petro MJ. Extracellular iron chelation in Cryptococcus neoformans. J Med Vet Mycol. 1987 Dec;25(6):415–418. [PubMed]
  • Vartivarian SE, Cowart RE, Anaissie EJ, Tashiro T, Sprigg HA. Iron acquisition by Cryptococcus neoformans. J Med Vet Mycol. 1995 May-Jun;33(3):151–156. [PubMed]
  • Johnson W, Varner L, Poch M. Acquisition of iron by Legionella pneumophila: role of iron reductase. Infect Immun. 1991 Jul;59(7):2376–2381. [PMC free article] [PubMed]
  • HOWARD DH. Some factors which affect the initiation of growth of Cryptococcus neoformans. J Bacteriol. 1961 Sep;82:430–435. [PMC free article] [PubMed]
  • Nathan CF. Secretory products of macrophages. J Clin Invest. 1987 Feb;79(2):319–326. [PMC free article] [PubMed]
  • Campbell EJ, Cury JD, Shapiro SD, Goldberg GI, Welgus HG. Neutral proteinases of human mononuclear phagocytes. Cellular differentiation markedly alters cell phenotype for serine proteinases, metalloproteinases, and tissue inhibitor of metalloproteinases. J Immunol. 1991 Feb 15;146(4):1286–1293. [PubMed]
  • Eissenberg LG, Goldman WE, Schlesinger PH. Histoplasma capsulatum modulates the acidification of phagolysosomes. J Exp Med. 1993 Jun 1;177(6):1605–1611. [PMC free article] [PubMed]
  • Zhu X, Ertel W, Ayala A, Morrison MH, Perrin MM, Chaudry IH. Chloroquine inhibits macrophage tumour necrosis factor-alpha mRNA transcription. Immunology. 1993 Sep;80(1):122–126. [PMC free article] [PubMed]
  • Ertel W, Morrison MH, Ayala A, Chaudry IH. Chloroquine attenuates hemorrhagic shock-induced immunosuppression and decreases susceptibility to sepsis. Arch Surg. 1992 Jan;127(1):70–76. [PubMed]
  • Misra UK, Gawdi G, Pizzo SV. Chloroquine, quinine and quinidine inhibit calcium release from macrophage intracellular stores by blocking inositol 1,4,5-trisphosphate binding to its receptor. J Cell Biochem. 1997 Feb;64(2):225–232. [PubMed]
  • Hart PD, Young MR. Ammonium chloride, an inhibitor of phagosome-lysosome fusion in macrophages, concurrently induces phagosome-endosome fusion, and opens a novel pathway: studies of a pathogenic mycobacterium and a nonpathogenic yeast. J Exp Med. 1991 Oct 1;174(4):881–889. [PMC free article] [PubMed]
  • BAKER RD, HAUGEN RK. Tissue changes and tissue diagnosis in cryptococcosis; a study of 26 cases. Am J Clin Pathol. 1955 Jan;25(1):14–24. [PubMed]
  • Zebedee SL, Koduri RK, Mukherjee J, Mukherjee S, Lee S, Sauer DF, Scharff MD, Casadevall A. Mouse-human immunoglobulin G1 chimeric antibodies with activities against Cryptococcus neoformans. Antimicrob Agents Chemother. 1994 Jul;38(7):1507–1514. [PMC free article] [PubMed]
  • Mazzolla R, Barluzzi R, Brozzetti A, Boelaert JR, Luna T, Saleppico S, Bistoni F, Blasi E. Enhanced resistance to Cryptococcus neoformans infection induced by chloroquine in a murine model of meningoencephalitis. Antimicrob Agents Chemother. 1997 Apr;41(4):802–807. [PMC free article] [PubMed]
  • Mackenzie AH. Pharmacologic actions of 4-aminoquinoline compounds. Am J Med. 1983 Jul 18;75(1A):5–10. [PubMed]
  • French JK, Hurst NP, O'Donnell ML, Betts WH. Uptake of chloroquine and hydroxychloroquine by human blood leucocytes in vitro: relation to cellular concentrations during antirheumatic therapy. Ann Rheum Dis. 1987 Jan;46(1):42–45. [PMC free article] [PubMed]
  • Crowle AJ, May MH. Inhibition of tubercle bacilli in cultured human macrophages by chloroquine used alone and in combination with streptomycin, isoniazid, pyrazinamide, and two metabolites of vitamin D3. Antimicrob Agents Chemother. 1990 Nov;34(11):2217–2222. [PMC free article] [PubMed]
  • Collins HL, Bancroft GJ. Encapsulation of Cryptococcus neoformans impairs antigen-specific T-cell responses. Infect Immun. 1991 Nov;59(11):3883–3888. [PMC free article] [PubMed]
  • Sperber K, Kalb TH, Stecher VJ, Banerjee R, Mayer L. Inhibition of human immunodeficiency virus type 1 replication by hydroxychloroquine in T cells and monocytes. AIDS Res Hum Retroviruses. 1993 Jan;9(1):91–98. [PubMed]
  • Sperber K, Louie M, Kraus T, Proner J, Sapira E, Lin S, Stecher V, Mayer L. Hydroxychloroquine treatment of patients with human immunodeficiency virus type 1. Clin Ther. 1995 Jul-Aug;17(4):622–636. [PubMed]

Articles from The Journal of Clinical Investigation are provided here courtesy of American Society for Clinical Investigation


Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...