Treatment of visceral leishmaniasis with pentavalent antimony and interferon gamma

Leishmaniases of the New World: current concepts and implications for future research

Recent epidemiologic studies indicate that leishmaniasis in the Americas is far more abundant and of greater public health importance than was previously recognized. The disease in the New World is caused by a number of different parasite species that are capable of producing a wide variety of clinical manifestations. The outcome of leishmanial infection in humans is largely dependent on the immune responsiveness of the host and the virulence of the infecting parasite strain. This article reviews current concepts of the clinical forms, immunology, pathology, laboratory diagnosis, and treatment of the disease as well as aspects of its epidemiology and control. Recommendations for future research on the disease and its control are made.

Interferon-gamma in starch microparticles: nitric oxide-generating activity in vitro and antileishmanial effect in mice

Recombinant mouse interferon-gamma (mu IFN-gamma) was covalently coupled to polyacryl starch microparticles, a lysosomotropic drug carrier. The microparticle-bound mu IFN-gamma was found to activate cultured macrophages for nitrite production and had an anti-leishmanial effect in mice. Low doses of mu IFN-gamma, which had no effect in the free form, when bound to microparticles significantly reduced the load of Leishmania donovani in infected mice. Further, inducement of nitrite production in cultured macrophages by microparticle-bound mu IFN-gamma required intact cell membrane receptors.

Cytokine regulation of T-cell function: potential for therapeutic intervention

CD4+ T cells, via the cytokines that they produce, play a pivotal role in the induction and regulation of cell-mediated and humoral immunity. Recently it has become clear that the CD4+ T-cell population is heterogeneous and that distinct CD4+ T-cell subsets, defined by their cytokine repertoire, regulate cell-mediated and humoral immune responses. Protective responses to pathogens are dependent on activation of the appropriate TH subset accompanied by its characteristic set of immune effector functions. Evidence to date suggests that the cytokines produced by the TH cells themselves are important regulators of TH subset activation and differentiation. Here, Fiona Powrie and Robert Coffman discuss how manipulation of the levels of these cytokines can be used to alter the balance of TH cell subsets and illustrate some clinical situations where this may be beneficial.

Cytokine regulation of T-cell function: potential for therapeutic intervention

CD4+ T cells, via the cytokines that they produce, play a pivotal role in the induction and regulation of cell-mediated and humoral immunity. Recently it has become clear that the CD4+ T-cell population is heterogeneous and that distinct CD4+ T-cell subsets, defined by their cytokine repertoire, regulate cell-mediated and humoral immune responses. Protective responses to pathogens are dependent on activation of the appropriate TH subset accompanied by its characteristic set of immune effector functions. Evidence to date suggests that the cytokines produced by the TH cells themselves are important regulators of TH subset activation and differentiation. Fiona Powrie and Robert Coffman discuss how manipulation of the levels of these cytokines can be used to alter the balance of TH-cell subsets and illustrate some clinical situations where this may be beneficial.

IFN-gamma treatment of rodents infected with erythrocytic stages of Plasmodium chabaudi: differential effects according to the immunological status

Recombinant rat interferon-gamma (rrIFN-gamma) was tested for its antimalarial activity in three different models of Plasmodium chabaudi-blood stage malaria. Doses ranging from 1 x 10(4) to 1 x 10(5) U of rrIFN-gamma were used in each model. In BALB/c mice (lethal infection), prophylactic treatment with daily intraperitoneal (i.p.) injections reduced parasitemia and delayed mortality. In contrast, subcutaneous administration of rrIFN-gamma was inefficient, as was curative schedule of i.p. administration. Euthymic Fischer rats, which develop an acute and resolutive infection, were partly protected by i.p. prophylactic administration of rrIFN-gamma. Parasitemia was reduced without being lengthened, resulting in a marked decrease in parasite burden. Subcutaneous administration was less efficient whereas curative schedule was not. Athymic (nude) Fischer rats which present a longlasting and stable infection were treated with prophylactic and curative schedules of i.p. administration of rrIFN-gamma. In each case, rrIFN-gamma-treated nude rats, as control nude rats, were unable to resolve their chronic infection. The conditions required to obtain a beneficial effect are thus restrictive for a therapeutic use in humans. Moreover, these results show that, despite the fact that IFN-gamma is considered as a major component of the immune response, this cytokine alone is not sufficient to induce the totality of the effector mechanisms necessary to cure malarial infections.

Leishmania donovani-reactive Th1- and Th2-like T-cell clones from individuals who have recovered from visceral leishmaniasis

Infections in humans by Leishmania donovani parasites can result in a fatal disease, visceral leishmaniasis (VL), or in a self-limiting asymptomatic infection. In murine models of the infection employing Leishmania major, the course of the disease can be directed into a VL-like syndrome by interleukin-4 (IL-4)-producing Th2 cells, or cure may result by Th1 cells secreting gamma interferon (IFN-gamma). The present study examined the potential of human T cells to generate Th1 or Th2 responses to L. donovani. The profiles of IFN-gamma, IL-4, and lymphotoxin secretion after antigen stimulation were analyzed in a panel of L. donovani-reactive CD4+ human T-cell clones generated from individuals who had recovered from VL after antimonial treatment. Two of the T-cell clones produced large amounts of IL-4 without production of IFN-gamma, seven clones produced both IFN-gamma and IL-4, and eight produced only IFN-gamma. This is the first report of a Th1- and Th2-type response in human leishmaniasis. These results suggest that in analogy with murine models, there is a dichotomy in the human T-cell response to L. donovani infections. Preferential activation of IL-4-producing Th2-like cells may be involved in the exacerbation of human VL, whereas activation of IFN-gamma-producing Th1 cells may protect the host from severe disease. Identification of leishmanial antigens activating one or the other type of T cells will be important in the development of vaccines against leishmaniasis.

Immunochemotherapy of visceral leishmaniasis: a pilot trial of sequential treatment with recombinant interferon-gamma and pentavalent antimony

The clinical, parasitological, hematological, and serological evolution of visceral leishmaniasis in Brazilian patients was assessed during treatment with human recombinant interferon-gamma (rIFN-gamma; 0.1 mg/m2 i.m. days 1-14) followed by pentavalent antimony (Sbv; 10 mg/kg days 22-28). At day 30, 6 patients had improved, 2 had slightly improved, and 1 patient had deteriorated. IFN-gamma was well tolerated in the dose tested and may be very effective as an adjunct to conventional therapy with antimony.

Visceral leishmaniasis after orthotopic liver transplantation: impact of persistent splenomegaly

Visceral leishmaniasis was observed in a 50-year-old female liver transplant recipient 1 year following transplantation. Signs of active infection were low-grade fever, pancytopenia, persistent splenomegaly, positive cultures for leishmania in liver and bone marrow biopsy specimens, and newly positive leishmania serology. Following sequential therapy with pentavalent antimony and amphotericin B, blood values improved massively, bone marrow cultures became negative, and leishmania serology decreased. Secondary prophylaxis with fluconazole was instituted and the patient remains without signs of active infection 1 year after successful therapy.

Nitric oxide-mediated cytostatic activity on Trypanosoma brucei gambiense and Trypanosoma brucei brucei

Macrophages collected from BCG-infected mice or exposed in vitro to interferon-gamma plus lipopolysaccharide developed a cytostatic activity on Trypanosoma brucei gambiense and Trypanosoma brucei brucei. This trypanostatic activity of activated macrophages was inhibited by addition of N-monomethyl-L-arginine, an inhibitor of the L-arginine-nitric oxide (NO) metabolic pathway, indicating a role for NO as the effector molecule. Contrary to trypanosomes treated with N2gas, trypanosomes treated with NO gas did not proliferate in vitro on normal macrophages. Compared to mice infected with control parasites, mice infected with NO-treated parasites had decreased parasitemias in the first days postinfection and had a prolonged survival. Addition of excess iron reversed the trypanostatic effect of both activated macrophages and NO gas. These data show that activated macrophages exert an antimicrobial effect on T.b. gambiense and T.b. brucei through the L-arginine-NO metabolic pathway. In trypanosomes, NO could trigger iron loss from critical targets involved in parasite division. The participation of this effector mechanism among the other immune elements involved in the control of African trypanosomes (antibodies, complement, phagocytic events) remains to be defined.

Transforming growth factor-beta in leishmanial infection: a parasite escape mechanism

The course of infection with the protozoan parasite Leishmania is determined in part by their early replication in macrophages, the exclusive host cells for these organisms. Although factors contributing to the survival of Leishmania are not well understood, cytokines influence the course of infection. Transforming growth factor-beta (TGF-beta) is a multipotential cytokine with diverse effects on cells of the immune system, including down-regulation of certain macrophage functions. Leishmanial infection induced the production of active TGF-beta, both in vitro and in vivo. TGF-beta was important for determining in vivo susceptibility to experimental leishmanial infection.

Recognition of Leishmania antigens by T lymphocytes from nonexposed individuals

Crude antigen preparations of Leishmania promastigote sonicates were found to induce in vitro proliferation and gamma interferon production in peripheral blood mononuclear cells (PBMC) from individuals without known exposure to the parasite. The proliferating cells were mainly CD2-positive T cells. The proliferative response was maximal after more than 6 days of incubation with the antigens in contrast to the proliferation induced by the mitogenic lectin phytohemagglutinin (PHA), which peaked after 3 to 5 days. Judged by limiting dilution analysis, the frequencies of antigen-reactive precursor cells were less than 1:10,000 and varied considerably between individuals. Depletion of CD45R0-positive (memory) cells from the PBMC abolished proliferative responses induced by Leishmania antigen and by tetanus toxoid. In cell populations depleted of CD45RA-positive (naive) cells, only a small reduction in response was observed. Cell populations depleted of either CD45R0-positive cells or CD45RA-positive cells both responded to PHA. We conclude that presumably unexposed individuals have a low number of Leishmania-reactive T cells in their circulatory systems. The Leishmania-reactive T cells in these individuals are most likely memory cells recognizing antigens present both in the Leishmania preparations and in the environment.

Biological properties of interleukin 10

An enormous amount of information on interleukin 10 (IL-10) has been gathered since its original description as cytokine synthesis inhibition factor (CSIF) several years ago. In this short article, Maureen Howard and Anne O'Garra summarize what is currently known of the biological properties of IL-10 and speculate on its clinical potential.

Preface: positive interactions between anti-infection drugs and the immune response: an emerging paradigm

In the third and fourth decades of this century chemotherapy began to be established as one of the greatest success stories in medicine. Now unfortunately severe problems compromise the efficacy of drugs used to treat infectious diseases, two of the most serious handicaps being the rapidity with which target pathogens can develop drug-resistance and the slow rate at which replacement products are appearing on the market. Increased understanding of the ways in which existing drugs act may help both to prolong their usefulness and to generate novel therapeutic strategies.

Chemotherapy and immunity in opportunistic parasitic infections in AIDS

Parasitic diseases are endemic in parts of the tropics, but there is no convincing evidence that their prevalence or incidence is increasing due to the HIV epidemic. Available scientific data on parasitic infections in patients with the Acquired Immunodeficiency Syndrome (AIDS) suggests a predominance of Pneumocystis carinii, Toxoplasma gondii and Cryptosporidium spp. For reasons which are unclear, parasitic infections such as Plasmodium falciparum, Strongyloides stercoralis and Entamoeba histolytica, where cell-mediated immune responses are also thought to be significant, do not appear to be opportunists of importance. It is being increasingly recognized that chemotherapy for parasitic diseases has a host-dependent component, although scientific data on this subject remain scanty. The management of opportunistic parasitic infections in patients infected with HIV is dogged by failures and relapses, aptly illustrating the notion of the relationship between chemotherapy and the immune response. This review discusses the immunity and chemotherapy of opportunistic parasite infections in patients infected with the Human Immunodeficiency Virus (HIV).

Interactions between immunity and chemotherapy in the treatment of the trypanosomiases and leishmaniases

The immune status of a host infected with Trypanosoma spp. or Leishmania spp. can play an important role in successful chemotherapy. In animal models, treatment of African trypanosomiasis with difluoromethylornithine or melarsoprol requires an appropriate antibody-mediated immune response. An intact immune system is also necessary for rapid clearance of trypanosomes from the bloodstream following treatment with suramin or quinapyramine. Similarly, an efficient cell-mediated immune responses is required for maximal efficacy of pentavalent antimonials in the treatment of leishmaniasis. However, the potential relationship between parasite-induced or acquired immunosuppression and effective chemotherapy has been poorly studied. Macrophages which have been activated by bacterial cell wall components or gamma-interferon are known to display increased activity against Leishmania donovani or Trypanosoma cruzi. In experimental and clinical visceral leishmaniasis, use of macrophage activators together with pentavalent antimonials has lowered the dose of antimony required to cure the infection.

Variations in susceptibility to Leishmania amazonensis infection in lines of mice selected for high or low immunoresponsiveness

The degree of resistance to a local Leishmania amazonensis challenge has been compared in lines of mice obtained by selective breeding for high or low immunoresponsiveness: High and Low antibody responder mice of Selections I and II (HI, HII and LI, LII lines) and high and low responder mice to T mitogen PHA (Hi/PHA and Lo/PHA). The aim of this preliminary study was to focus attention on genetic differences related with well defined immune characteristics. Clear-cut results were obtained, both HI and HII mice developed large and disseminating lesions, the rate of symptom aggravation being faster in HII, while LI and LII proved resistant to parasites, only small and transient lesions being observed for them during a 150 days follow up. The outcome of infection also differs in Hi/PHA and Lo/PHA mice, Hi/PHA having a resistant and Lo/PHA a susceptible phenotype.

Visceral leishmaniasis in an HIV-infected patient: clinical features and response to treatment

We report the case of 43-year-old homosexual patient with HIV infection and a history of travel to the Far East in whom visceral leishmaniasis was the first infectious complication. Symptoms were fever, malaise, weight loss, hepatosplenomegaly, generalized lymphadenopathy, and oral thrush. Laboratory abnormalities included a slight elevation of liver enzymes, impairment of liver function tests, leukocytopenia, anemia, hypergammaglobulinemia, and markedly depressed CD4(+)-cell counts. Despite initially successful treatment with pentavalent antimony, a relapse of leishmaniasis occurred after 7 months. Eradication of the infection was not achieved. Treatment was continued as a palliative chronic suppressive treatment with fortnightly pentamidine infusions. The clinical course was complicated by legionella pneumonia and the development of rapidly progressing Kaposi's sarcoma. The case is presented in detail, and the influence of HIV infection on the course of leishmaniasis is discussed.

Cytokines in clinical cancer therapy

Cytokines have been of much interest in clinical cancer therapy research over the past decade. One important advance during the past year has been the clear demonstration, in large prospective randomized studies, that granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor reduce the neutropenia-related morbidity of cancer therapy.

Evidence of subjects sensitized to Leishmania infantum on the French Mediterranean coast: differences in gamma interferon production between this population and visceral leishmaniasis patients

The Marseilles region is an endemic area for visceral mediterranean leishmaniasis, but although the number of dog cases, the parasite's main host, is very high, only a few people develop the disease. We looked for sensitized healthy subjects among 25 healthy individuals living in this area by studying their in vitro lymphoproliferative response to Leishmania infantum antigens and gamma interferon synthesis. We found that 65% of tested subjects were sensitized against L. infantum. We compared their cell mediated immunity to that of 13 active Kala-Azar patients and 13 controls from non-endemic areas. In patients, results showed a specific cellular immuno-deficiency in the lymphocyte response to L. infantum antigens and a global deficiency of gamma interferon production. Interestingly, the healthy individuals from the endemic area who responded to L. infantum antigens were found to produce high gamma interferon levels after L. infantum antigen stimulation. After healing, the cell mediated-immunity of the 3 patients we followed up was similar to that of the sensitized tested healthy subjects, but the former were still producing antibodies at the time of study.

Imported and autochthonous kala-azar in France

OBJECTIVE

To study the epidemiological, clinical, and biological features of imported and autochthonous kala-azar in France.

DESIGN

Prospective survey of all patients in France with kala-azar diagnosed over the two years 1986-7. Information was obtained from parasitology laboratories in regional hospitals and all hospital laboratories and haematology departments capable of diagnosing leishmaniasis in the south of France.

SETTING

107 public hospitals in France.

PATIENTS

89 patients with kala-azar.

INTERVENTIONS

All patients were treated with drugs. In the first instance meglumine antimonate was given to all but two patients.

MAIN OUTCOME MEASURES

Prevalence of the various clinical and biological features of kala-azar; proportion of patients with HIV infection.

RESULTS

Half (44) of the patients were children under 8 years old. Seventy patients acquired the disease in France. Imported kala-azar was acquired mainly in Mediterranean countries (9/18 cases). Only 46 (52%) of the patients had all three of the classic associated clinical features of fever, splenomegaly, and hepatomegaly. Anaemia was the commonest biological sign, and the association of the four usual biological signs--anaemia, leucopenia, thrombocytopenia, and hypergammaglobulinaemia--was present in only 14 (33%) of the children under 8 and 26 (60%) adults. Fourteen of the patients over 8 years old were infected with HIV.

CONCLUSION

Doctors must be aware of kala-azar in Mediterranean areas, especially as patients often present without the characteristic features and the disease affects young children preferentially.

Organ specific cytokine therapy. Local activation of mononuclear phagocytes by delivery of an aerosol of recombinant interferon-gamma to the human lung

In the context of the central role of the alveolar macrophage in host defense of the respiratory epithelial surface, and the ability of IFN-gamma to activate mononuclear phagocytes, we have evaluated strategies to use rIFN-gamma to activate human alveolar macrophages in vivo. To accomplish this, rIFN-gamma was administered to nonsmoking normals, the amounts of IFN-gamma quantified in serum and respiratory epithelial lining fluid (ELF) and the status of IFN-gamma related activation of blood monocytes and alveolar macrophages was evaluated by quantifying the expression of mRNA transcripts of IP-10, a gene induced specifically by IFN-gamma. Systemic administration (subcutaneous) of maximally tolerated amounts of rIFN-gamma (250 micrograms) was followed by detectable levels of IFN-gamma in serum but not ELF, the expression of IP-10 transcripts in blood monocytes but not alveolar macrophages, and multiple systemic adverse effects. To circumvent the inability of systemic administration to reach respiratory ELF and activate alveolar macrophages, rIFN-gamma (250-1,000 micrograms) was inhaled as an aerosol once daily for 3 d. Strikingly, while IFN-gamma was not detected in serum it was detectable in respiratory ELF in a dose-dependent fashion. Further, alveolar macrophages, but not blood monocytes, expressed IP-10 mRNA transcripts and, importantly, inhalation of aerosolized rIFN-gamma was not associated with local or systemic adverse effects. Thus, it is feasible to use rIFN-gamma to activate alveolar macrophages by targeting the cytokine directly to the lung. These data suggest a potential strategy for targeted cytokine therapy, without systemic side effects, to augment respiratory tract defenses in individuals at risk for or with lung infection.

Suppression by human recombinant gamma interferon of in vitro macrophage nonopsonic and opsonic phagocytosis and killing

Although gamma interferon (IFN-gamma) exerts profound effects on the state of activation of macrophages, its influence on receptor-mediated phagocytosis and killing of extracellular bacteria is poorly understood. Human monocytes cultured in the presence of human recombinant IFN-gamma exhibited an enhanced capacity to produce superoxide anion. Although these cells bound greater numbers of particles via Fc receptors, their capacity to phagocytose by these receptors or to bind or ingest particles via receptors for C3bi, mannose, or unopsonized Pseudomonas aeruginosa was substantially depressed in a dose-dependent fashion (0.1 to 1,000 U of IFN-gamma per ml). Macrophage phagocytosis of P. aeruginosa and Staphylococcus aureus opsonized with whole serum or with serum deficient in immunoglobulin or complement was also depressed. Macrophages cultured in the presence of IFN-gamma had a diminished capacity to kill both unopsonized and opsonized P. aeruginosa. We conclude that IFN-gamma inhibits macrophage nonopsonic and opsonic receptor-mediated phagocytosis and killing but enhances oxidative radical generation; its production may exacerbate host tissue damage during chronic infection with extracellular pathogens.

Gamma interferon suppresses acute and chronic Trypanosoma cruzi infection in cyclosporin-treated mice

To determine if exogenous gamma interferon is effective in immunosuppressed mice infected with Trypanosoma cruzi, recombinant murine gamma interferon was administered to cyclosporin-treated mice with either acute or chronic T. cruzi infection. Gamma interferon significantly decreased parasitemia and prevented death in acutely infected mice. Parasitemias and mortality of mice treated with both gamma interferon and cyclosporin were similar to those of immunocompetent controls. In chronically infected mice, cyclosporin treatment produced significantly more organ explant cultures positive for T. cruzi. Fewer positive cultures, particularly for spleen and heart, were obtained from cyclosporin-treated mice when they also received gamma interferon. Ketoconazole treatment of mice resulted in no positive cultures. Cyclosporin treatment did not prevent activation of peritoneal macrophages by parenteral gamma interferon, nor did it have a consistent effect on serum titers of alpha/beta or gamma interferon in response to a second challenge inoculum of T. cruzi. These data indicate that exogenous gamma interferon suppresses acute and chronic T. cruzi infection in cyclosporin-treated mice but that gamma interferon is not as effective as the relatively specific antimicrobial ketoconazole. Gamma interferon activates macrophages despite cyclosporin treatment, and its effects appear to be tissue specific.

A controlled trial of interferon gamma to prevent infection in chronic granulomatous disease

BACKGROUND

Chronic granulomatous disease is an uncommon inherited disorder of phagocytes in which defective production of the reactive intermediates of oxygen predisposes patients to recurrent and severe pyogenic infections. Evidence from in vitro and in vivo studies indicates that interferon gamma can partially correct the metabolic defect in phagocytes. We assessed the efficacy of interferon gamma in decreasing the frequency of serious infections in patients with this disease.

METHODS

We conducted a randomized, double-blind, placebo-controlled study in 128 patients with chronic granulomatous disease (median age, 15 years). Patients received interferon gamma (50 micrograms per square meter of body-surface area) or placebo subcutaneously, three times a week for up to a year. The primary end point of the study was the time to the first serious infection, defined as an event requiring hospitalization and parenteral antibiotics. Measures of phagocyte function were also monitored.

RESULTS

In terms of the time to the first serious infection, there was a clear benefit from interferon as compared with placebo (P = 0.0006). Of the 63 patients assigned to interferon, 14 had serious infections, as compared with 30 of the 65 patients assigned to placebo (P = 0.002). There was also a reduction in the total number of serious infections--20 with interferon as compared with 56 with placebo (P less than 0.0001). Interferon was beneficial regardless of age, the use or nonuse of prophylactic antibiotics, and the mode of inheritance (X-linked or autosomal recessive). However, there were no significant changes in the measures of superoxide production by phagocytes. Interferon therapy was well tolerated, and there was no evidence of serious toxicity.

CONCLUSIONS

For patients with chronic granulomatous disease, interferon gamma therapy is an effective and well-tolerated treatment that reduces the frequency of serious infections.

Interferon-gamma and chronic granulomatous disease

The molecular and biochemical characterization of many components of the phagocyte oxidase complex that generates superoxide have greatly advanced our understanding of this important pathway. Genetic defects in one or more of the components of this host defense system result in the chronic granulomatous disease phenotype. Biochemical advances and the results of a clinical trial that established the efficacy of recombinant human interferon-gamma for prophylaxis of infections in chronic granulomatous disease are the highlights of recent achievements in this area of phagocyte biology.

Visceral leishmaniasis in patients infected with human immunodeficiency virus. Co-operative Group for the Study of Leishmaniasis in AIDS

We describe 40 HIV-seropositive patients who developed visceral leishmaniasis. All the patients lived in areas endemic for visceral leishmaniasis and belonged to groups at risk for AIDS. Twenty-three patients (57.2%) had definitive AIDS before or after diagnosis of leishmaniasis and 77.5% were classified as belonging to CDC group IV. Fever was present in 95% patients and enlargement of the liver and/or spleen in 92.5%. Lymphopenia was found in 78.3%, depression of the absolute number of CD4 lymphocytes in 90% and depression of the CD4 to CD8 ratio in all evaluated cases but leishmania antibodies were found in only 35.2%. Parasites were demonstrated in the bone marrow or liver in every case. Thirty patients (75%) showed an initial good response to antimonial drugs, although the leishmaniasis followed a chronic or relapsing course in 17 (42.5%). HIV-related mortality was 40%. A significant correlation was found only between the relapsing course of the disease and mortality. In a multivariate linear regression model, the relapsing course was the only variable that influenced mortality. Visceral leishmaniasis is an opportunistic disease that should be suspected in HIV-infected patients. We suggest that it should be included in the CDC group IV C-1 and considered as a disease indicative of AIDS.

Role of human recombinant GM-CSF in the prevention and treatment of leukopenia with special reference to infectious diseases

Recombinant human GM-CSF has been shown to be effective in reversing severe neutropenic states associated with the underlying disease or caused by cytotoxic drugs, and during engraftment after bone marrow transplantation. Preliminary evidence supports the view that restoration of adequate myelopoiesis results in better control of infection. The use of rhGM-CSF in special infectious diseases to activate cell function is currently being studied. Preliminary in vitro and in vivo data allow high expectations for the usefulness of rhGM-CSF in contributing to the control of these diseases.