The immunology of mycobacterial infections

In vivo kinetics of peripheral cellular immune responses in Mycobacterium avium subspecies paratuberculosis (MAP) infected and vaccinated goats

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of paratuberculosis (ParaTB) also known as Johne's disease (JD) in ruminants, which is characterized by chronic intestinal inflammation. A similar counterpart has been observed in the form of Crohn's disease in humans. The present study is the first trail in goats to understand the peripheral cellular immune responses following experimental MAP infection and vaccination. Fifteen apparently healthy male kids (3-6 months old) of Barbari breed were included in this study. In the experimental study, 5 kids were infected with 'S 5' strain of MAP ("Indian Bison Type"), 5 were vaccinated (Indigenous Vaccine) against MAP infection (Singh et al., 2007) and the remaining 5 kids were uninfected and non-vaccinated controls. Kids were observed for a period of 180 days post exposure (infection and vaccination) and were tested for development of infection. Cellular immune responses (in blood) were recorded post-exposure by three assays. We measured the frequencies of CD4 and CD8T cells, estimated plasma IFNγ and TNα and in the third assay, in vitro cytokine production by peripheral blood mononuclear cells (PBMCs) from vaccinated, infected and controls were examined in response to polyclonal stimulation. The frequencies of peripheral CD4 and CD8T cells were comparable in control, infected and vaccinated animals except around day 49 post-infection where MAP infected animals showed a trend towards significantly reduced frequencies of CD4 T cells compared to apparently healthy controls. Significantly reduced plasma TNFα levels were also observed in infected animals compared to vaccinated animals,during the course of infection. Diminished levels (although non significant) of TNFα were observed in the supernatants from polyclonally stimulated PBMCs at around day 49 post infection. It is conceivable that the diminished cellular immune responses may coincide with an impairment (immune exhaustion) of perhaps antigen-specific CD4T cells that might, in the course of infection, contribute to the progressive nature of caprine paratuberculosis.

Bezerra K, I. N. Oliveira J, Albuquerque EL, Fulco UL. Binding energies of the drugs capreomycin and streptomycin in complex with tuberculosis bacterial ribosome subunits

We calculated the interaction binding energies of the drugs capreomycin and streptomycin in complex with the tuberculosis bacterial ribosome subunits.

Mechanisms of Granulomatous Lung Disease from Inhaled Beryllium: The Role of Antigenicity in Granuloma Formation

Granulomatous lung disease is a debilitating and sometimes fatal condition encountered in humans, for which the cellular and molecular mechanisms are poorly understood. Two patterns of granulomatous lung disease are recognized; foreign-body reactions and immune-mediated granulomas. Beryllium inhalation by humans results, in a small number of exposed individuals, in a chronic, granulomatous, immune-mediated pulmonary disease (chronic beryllium lung disease, CBD). Animal models used to study CBD have demonstrated significant species differences in the pathologic response to beryllium. While rats exposed to beryllium appear to develop a chronic, foreign-body response within the lung, dogs so exposed develop beryllium-specific immune responses within the lung and blood, accompanied by immune granulomas within the lung. At the heart of this difference appears to be the ability of the dog, but not the rat, to immunologically recognize the antigenicity of beryllium. This important difference further underscores the need to understand the mechanistic differences among similar disease syndromes, particularly if therapeutic regimens are to be used.

BCG expressing LCR1 of Leishmania chagasi induces protective immunity in susceptible mice

Cellular immune responses are required for protective immunity against Leishmania chagasi. Immunization strategies using live intracellular bacteria (e.g., bacille-Calmette Guerin strain of Mycobacterium bovis) expressing recombinant antigens can induce cellular immune responses to these antigens. Previous studies demonstrated that the L. chagasi antigen LCR1 stimulates IFN-gamma production from T cells of infected BALB/c mice, and immunization with recombinant LCR1 partially protects against L. chagasi infection. To determine whether live bacteria could enhance the immunization potential of LCR1, we engineered BCG expressing LCR1 (BCG-LCR1). Subcutaneous immunization with BCG-LCR1, but not with BCG containing plasmid only (BCG-pMV261), elicited better protective immunity against L. chagasi infection than LCR1 protein alone. BCG-LCR1 administered intraperitoneally did not protect. Splenocytes from mice immunized s.c. with either BCG-LCR1 or BCG-pMV261 and then infected with L. chagasi promastigotes had increased antigen-induced IFN-gamma and reduced IL-10 production compared to splenocytes of control mice. We propose that BCG-LCR1 promotes a Th1-type protective immune response, and it may be a useful component of a Leishmania vaccine.

Immunology: resistance to paratuberculosis

Disease caused by Mycobacterium paratuberculosis involves a complex interaction of lymphoid and phagocytic cells of the peripheral and mucosal immune responses. For resistance to develop, animals must generate an effective cellular immune response to primary infections as well as multifocal exogenous and endogenous reinfections. If an effective immune response does not develop, infected animals transgress through a complex immunologic spectrum in which the immunologic reactions themselves are responsible for the disease manifestations.

Immunological analysis of the components of the antigen complex A60 of Mycobacterium bovis BCG

The antigen complex of A60 of Mycobacterium bovis BCG was analyzed by different immunological techniques to assess its relevance to tuberculosis and the involvement of its components in the immune reactions elicited in humans by tuberculous infection. A60 is composed of about 30 components, of which 8 were identified by available monoclonal antibodies (lipoarabinomannan, a glycolipid, and proteins of 65, 40, 38, 35, 19, and 14 kDa). The majority (87.5%) of anti-mycobacterial antibodies in sera from tuberculosis patients was directed against A60. Western blot (immunoblot) analysis indicated that the majority of the highly antigenic proteins present in mycobacterial homogenates were components of the A60 complex. A small percentage (7.8%) of A60 epitopes proved to be species specific. Thus, A60 proteins of 66, 41, 38, 37, 35, 34, 32, and 22 kDa were found to contain B-cell epitopes specific for M. bovis and not shared by Mycobacterium leprae oR Mycobacterium avium.

Presentation of mycobacterial antigens by human dendritic cells: lack of transfer from infected macrophages

When exposed to a challenge of 10 Mycobacterium bovis BCG cells per antigen-presenting cell, most human monocytes engulf several organisms. In contrast, blood dendritic cells which are potent antigen-presenting cells for several antigens are not detectably phagocytic for mycobacteria. We investigated the possibility that infected macrophages might regurgitate antigens for presentation by populations of human blood dendritic cells. Macrophages were infected with M. bovis BCG, mixed with uninfected dendritic cells, and added to immune T cells, either bulk T cells or cloned populations from BCG vaccinees or patients recovering from tuberculosis. The macrophages were from donors who were mismatched to the T cells so that transfer of antigen to major histocompatibility complex-matched dendritic cells could be evaluated. As we describe, there was no evidence for the transfer of mycobacterial antigens from macrophages to dendritic cells in a form that was stimulatory for the T cells.

Lepromatous leprosy treated with recombinant interferon gamma: cutaneous histologic changes

We report on the histologic changes occurring in single cutaneous lesions, from six active lepromatous patients, 1 week following the administration of three daily intradermal injections, 35 micrograms each, of recombinant interferon gamma (rIFN-gamma). Except for a strong induration at the injection site, rIFN-gamma produced no adverse systemic reactions and was able to promote a remarkable influx of T-lymphocytes, mononuclear phagocytes with large nuclei, nonvacuolated cytoplasm, and reduced lysozyme reactivity. Furthermore, despite no clear-cut reduction of mycobacterial dermal burden, bacilli showed a clear increase in the granular appearance. Present findings provide a basis for further elucidation of rIFN-gamma as an additional tool for leprosy treatment.

Oxidative metabolic status of blood monocytes and alveolar macrophages in the spectrum of human pulmonary tuberculosis

The oxidative metabolic status of blood monocytes (BM) and alveolar macrophages (AM) in patients with active pulmonary tuberculosis (TB) (n = 40) and in successfully treated patients (n = 40) was assessed and compared with that of healthy control subjects (n = 40). Oxygen free radical (OFR) generation, measured by chemiluminescence (CL) and cytochrome c reduction assay and confirmed by using scavengers of different OFR, was suppressed in AM of the pulmonary TB group compared with healthy controls, whereas it was enhanced in BM. Successfully treated patients showed partial recovery of CL and cytochrome c reduction in AM. There was no significant change in BM of patients after having been treated. The overall capacity to generate OFR was markedly suppressed upon in vitro stimulation with latex in both BM and AM of TB patients. The observed suppressed oxidative metabolic activity in BM and AM was further elucidated by studying the molecular mechanism of respiratory burst. The activities of NADPH oxidase and enzymes of the hexose monophosphate (HMP) shunt were significantly (p less than 0.05) decreased in BM and AM of pulmonary TB patients compared with healthy controls. Patients who had been treated showed marked recovery of NADPH oxidase and HMP shunt activity. The present study suggests that tubercle bacilli escape the microbicidal action of macrophages as a result of suppressed OFR generation caused by decreased activity of HMP shunt, leading to decreased levels of NADPH, thereby preventing NADPH oxidase from working at its full capacity.

Evidence that coating of Mycobacterium leprae surface antigens reduces its ability to hinder host microbicidal functions

Mycobacterium leprae extracted and purified from experimentally infected armadillo was coated with rabbit sera raised against the total antigens of the following species of mycobacteria: M. leprae, M. avium, M. bovis BCG, and M. fallax. In addition, the bacteria were also coated either with serum from a lepromatous (LL), or a tuberculoid (TT) leprosy patient. The effectiveness of surface coating was verified by electron microscopy, with the aid of gold immunolabelling. The coated bacilli were phagocytized by mice bone marrow-derived macrophages, and the phagosome-lysosome fusions (PLF) were assessed during phagocytosis using acid-phosphatase (AcPase) cytochemistry. As compared to control preparations (like-wise treated with non-immune serum), significant but partial reversion of PLF inhibition was observed in all cases except when bacteria had been incubated with M. fallax antiserum (rapidly growing, non-pathogenic species). The results obtained suggest that some of the antimycobacterial antibodies may offer partial protection to the host during early events of infection by reverting the usual pattern of inhibition of PLF in infected macrophages.

Development of a diagnostic test for Johne's disease using a DNA hybridization probe

A DNA probe, M13 mpHAW71, that detects Mycobacterium paratuberculosis in the fecal material of infected animals was developed for use in the diagnosis of Johne's disease. The probe detected as few as 10(5) M. paratuberculosis when hybridized under stringent conditions to total genomic DNA purified from bovine fecal material. When the probe was used diagnostically, it did not differentiate members of the Mycobacterium avium-M. intracellulare-M. paratuberculosis complex. Compared with culturing, the DNA probe identified 34.4% more mycobacterium-containing fecal samples, and testing took only 72 h to complete.

A 25-kilodalton fraction from Mycobacterium tuberculosis that inhibits hexose monophosphate shunt activity, lysozyme release, and H2O2 production: reversal by gamma interferon

This study examined the effects of a 25-kilodalton (kDa) glycolipoprotein derived from Mycobacterium tuberculosis on phagocyte functions associated with antimicrobial activity. The 25-kDa fraction inhibited the ability of both polymorphonuclear cells and cultured monocytes to release lysozyme and produce hydrogen peroxide. In addition, the glycolipoprotein was capable of reducing hexose monophosphate shunt activity and interfered with the ability of polymorphonuclear cells to reduce Nitro Blue Tetrazolium. Inhibition of these antimicrobial systems was optimal at a 50-micrograms/ml concentration of the 25-kDa fraction. Gamma interferon, but not alpha interferon, partially reversed the inhibitory effect of the mycobacterial component in all of the systems assessed. These studies indicate important mechanisms in the understanding of the pathogenesis of tuberculosis and suggest that gamma interferon may have a therapeutic role in mycobacterial diseases.

Crohn's disease and the mycobacterioses: a review and comparison of two disease entities

Crohn's disease is a chronic granulomatous ileocolitis, of unknown etiology, which generally affects the patient during the prime of life. Medical treatment is supportive at best, and patients afflicted with this disorder generally live with chronic pain, in and out of hospitals, throughout their lives. The disease bears the name of the investigator who convincingly distinguished this disease from intestinal tuberculosis in 1932. This distinction was not universally accepted, and the notion of a mycobacterial etiology has never been fully dismissed. Nevertheless, it was 46 years after the distinction of Crohn's disease and intestinal tuberculosis before research attempting to reassociate mycobacteria and Crohn's disease was published. Recently, there has been a surge of interest in the possible association of mycobacteria and Crohn's disease due largely to the isolation of genetically identical pathogenic Mycobacterium paratuberculosis from several patients with Crohn's disease in the United States, the Netherlands, Australia, and France. These pathogenic organisms have been isolated from only a few patients, and direct evidence for their involvement in the disease process is not clear; however, M. paratuberculosis is an obligate intracellular organism and strict pathogen, which strongly suggests some etiologic role. Immunologic evidence of a mycobacterial etiology, as assessed by humoral immune determinations, has been conflicting, but evaluation of the more relevant cellular immunity has not been performed. Data from histochemical searches for mycobacteria in Crohn's disease tissues have been equally conflicting, with acid-fast bacilli detected in 0 to 35% of patients. Animal model studies have demonstrated the pathogenic potential of isolates as well as elucidated the complexity of mycobacterial-intestinal interactions. Treatment of Crohn's disease patients with antimycobacterial agent has not been fully assessed, although case reports suggest efficacy. The similarities in the pathology, epidemiology, and chemotherapy of Crohn's disease and the mycobacterioses are discussed. The issue is fraught with controversy, and the data generated on the association of mycobacteria and Crohn's disease are in their infantile stages so that a general conclusion on the legitimacy of this association cannot be made. While no firm evidence clearly implicates mycobacteria as an etiologic agent of Crohn's disease, the notion is supported by suggestive and circumstantial evidence and a remarkable similarity of Crohn's disease to known mycobacterial diseases.

Differences in uptake of mycobacteria by human monocytes: a role for complement

We investigated the influence of serum factors on the uptake of various species of mycobacteria by human peripheral blood monocytes (PBM). On the basis of the percentage of PBM involved during in vitro uptake, the mycobacteria were of two distinct groups. The mycobacteria of one group, which consisted of Mycobacterium avium complex and M. chelonae, were taken up by many PBM; the other group, consisting of M. tuberculosis, M. kansasii, M. fortuitum, and M. gordonae, were taken up by fewer PBM. M. scrofulaceum was intermediate to these two groups on the basis of its uptake by PBM. Serum depleted of complement by heating or treatment with cobra venom factor significantly reduced the extent of PBM involvement with M. avium complex, indicating that complement is an important serum component mediating the uptake of M. avium complex organisms. Preincubation of mycobacteria with serum containing 10 mM EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] and 10 mM MgCl2 resulted in uptake by a high percentage of PBM, while preincubation in heated serum or serum containing 10 mM EDTA resulted in a significantly reduced percentage of PBM involved in uptake of M. avium complex organisms, indicating that these organisms are activators of the alternative pathway of complement. Incubation of M. avium complex organisms in human serum consumed 51% of the hemolytic complement activity. Parallel experiments indicated that serum had a lesser effect on the uptake of M. tuberculosis. Thus, serum is important in in vitro M. avium complex uptake by PBM; complement has a major role in the effect of serum, but this role is less important with M. tuberculosis.

The Mycobacterium tuberculosis 65-kilodalton antigen is a heat shock protein which corresponds to common antigen and to the Escherichia coli GroEL protein

Monoclonal hybridoma antibodies directed against a 65-kilodalton (kDa) mycobacterial protein could detect similarly sized antigens in many other bacterial species. In Pseudomonas aeruginosa, the cross-reacting protein corresponded to a 62-kDa antigen that has been called Common Antigen. The mycobacterial 65-kDa antigen and Common Antigen are similar in that both (i) are highly immunoreactive molecules, (ii) contain species-specific and genus-specific epitopes in addition to the broadly cross-reactive epitopes, (iii) can be isolated as homomultimers of greater than 240 kDa, and (iv) have similar amino acid compositions. In Escherichia coli, the cross-reactive protein corresponded to the GroEL protein. Both the GroEL protein and the mycobacterial 65-kDa protein are expressed as heat shock proteins.

Mycobacterium avium-intracellulare complex infections in the acquired immunodeficiency syndrome

This review examines an important bacterial infection in acquired immunodeficiency syndrome (AIDS). Despite occasional infections with bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, Salmonella, and Nocardia in patients with AIDS, the primary problems of AIDS and invading bacterial infections center around mycobacteriosis. A unique feature of AIDS has been the common identification of disseminated infections with Mycobacterium avium-intracellulare. The following discussion examines our present understanding of this group of organisms and how they interact with the compromised host.

Inhibition by 1,25(OH)2-vitamin D3 of the multiplication of virulent tubercle bacilli in cultured human macrophages

Historically, sunlight has seemed to fortify antituberculosis resistance. Evidence is presented here suggesting a role for vitamin D in this effect. The active metabolite of this photosynthesized vitamin, 1,25-dihydroxy-vitamin D3 (1,25D), promotes maturation and activation of human monocytes and macrophages (MPs). Therefore, it was tested for ability to protect MPs against virulent tubercle bacilli. MPs were derived by 7-day culture from blood monocytes, infected with the bacilli, and exposed to 1,25D in several regimens. Their inhibition of bacilli was measured by lysing samples of the cultures at 0, 4, and 7 days after infection and making bacillary CFU counts from serial dilutions of the lysates. 1,25D enabled MPs to slow or stop bacillary replication. Autologous serum supported the 1,25D-induced protection because the vitamin was not effective in medium supplemented with a serum substitute and was less effective in a heterologous AB serum than in autologous serum. The protection developed rapidly and could be induced even when 1,25D was added 3 days after infection. A concentration on the order of 4 micrograms/ml was needed for protection by the regimens used in these experiments. That is considerably higher than normal circulating concentrations of 1,25D but could be reached in infectious granulomas, because MPs can make 1,25D from precursor 25-hydroxyvitamin D3. The precursor circulates at levels 10(3) higher than those of 1,25D and is directly influenced by dietary intake or photosynthetic production of vitamin D. These results identify 1,25D as an immunomodulator which can reproducibly activate human MPs to express tuberculoimmunity. They connect vitamin D, sunlight, and tuberculoimmunity and suggest that vitamin D should be considered a vital factor in the practical control of tuberculosis.

Isolation and restriction site maps of the genes encoding five Mycobacterium tuberculosis proteins

A series of recombinant phage expressing five Mycobacterium tuberculosis antigens were isolated. Restriction maps for these antigens were deduced, and the size of the expressed proteins was determined.

Characterization, sequence determination, and immunogenicity of a 64-kilodalton protein of Mycobacterium bovis BCG expressed in escherichia coli K-12

We report the DNA sequence of a previously cloned Mycobacterium bovis BCG gene encoding an immunogenic 64-kilodalton protein. This protein, MbaA, was purified from overproducing Escherichia coli K-12 cells, and the presence of antibodies to MbaA in human sera was determined by an enzyme-linked immunosorbent assay. In about 80% of serum samples from tuberculosis patients and in about 60% of samples from BCG-vaccinated individuals, significant levels of anti-MbaA antibodies were found. Surprisingly, in about 30% of the control serum samples obtained from children, anti-MbaA antibodies were also observed. Guinea pigs sensitized with M. bovis BCG or MbaA showed a delayed-type hypersensitivity reaction after challenge with purified MbaA, supporting the previously observed strong reactivity of human T-cell clones with this, for mycobacteria, common antigen.

The 65-kilodalton antigen of Mycobacterium tuberculosis

The immune response of the host to the antigens of Mycobacterium tuberculosis plays the key role in determining immunity from infection with as well as the pathogenicity of this organism. A 65-kilodalton (kDa) protein has been identified as one of the medically important antigens of M. tuberculosis. The gene encoding this antigen was isolated from a lambda gt11-M. tuberculosis recombinant DNA library using monoclonal antibodies directed against the 65-kDa antigen as the specific probes. The nucleotide sequence of this gene was determined, and a 540-amino-acid sequence was deduced. This sequence was shown to correspond to that of the 65-kDa antigen by constructing a plasmid in which this open reading frame was fused to the lacZ gene. The resulting fusion protein reacted specifically with the anti-65-kDa protein antibodies. A second long open reading frame was found downstream of the 65-kDa antigen gene which could encode a protein of 517 amino acids. This putative protein contained 29 tandemly arranged partial or complete matches to a pentapeptide sequence.

Comparison of 15 laboratory and patient-derived strains of Mycobacterium avium for ability to infect and multiply in cultured human macrophages

Mycobacterium avium is a cause of nontuberculous chronic granulomatous infections which is attracting increased attention as a frequent opportunistic pathogen in acquired immunodeficiency syndrome. Some important aspects of its human pathogenicity were investigated by using cultured human macrophages infected with it. The uptake and replication of various strains of M. avium in the macrophages could be measured by CFU counts of the bacteria in samples of lysed, sonicated macrophages. Microscopic counts of acid-fast bacilli were not useful because the bacteria multiplying in the macrophages were usually not acid fast. Electron microscopy showed the intracellular bacilli to multiply by transverse fission, to be surrounded in individual vacuoles by a broad electronlucent zone, and to have thinner cell walls than extracellularly grown M. avium. Fifteen strains, including examples of serovars 1, 2, 4, 8, and 9, were studied for uptake and rate of replication in cultured macrophages from three normal subjects. The strains were isolates from patients with nontuberculous granulomatous infection, acquired immunodeficiency syndrome, or unrelated problems, or they were laboratory reference cultures. There were no differences among them in phagocytosis, but there were differences in intracellular replication. Laboratory strains tended to be avirulent, that is, they did not replicate in the macrophages. Patient isolates usually were virulent and could be compared for virulence by intracellular replication rates. Virulence correlated with flat, transparent bacterial colony morphology on nutrient agar but not with serovar or kind of patient from whom the bacteria were isolated. However, among strains of transparent colony morphology there were wide differences in virulence. A virulent bacilli generally produced domed, opalescent colonies on nutrient agar. A virulent bacilli predominated in populations of M. avium conditioned to growth in bacteriologic culture medium. Bacilli of virulent colony morphology predominated in populations passaged through cultured macrophages. The model described here presents a new approach to the investigation of the pathogenicity of M. avium for human subjects and may be more patient relevant than animal models.

Cloning of Mycobacterium bovis BCG DNA and expression of antigens in Escherichia coli

A gene bank of Mycobacterium bovis BCG DNA in Escherichia coli was constructed by cloning Sau3A-cleaved mycobacterium DNA fragments into the lambda vector EMBL3. The expression of mycobacterial antigens was analyzed by Western blotting with hyperimmune rabbit sera. Among 770 clones tested, several were found that produced various mycobacterial antigens in low amounts, with concentrations generally close to the detection limit. One particular clone was chosen for further investigation. This clone produced a 64-kilodalton (kDa) antigen. By placing the lambda promoter PL in front of the structural gene of this antigen, an overproducing E. coli strain was obtained. Rocket-line immunoelectrophoresis experiments showed that antigens cross-reacting with the 64-kDa protein are present in a wide variety of mycobacteria and also in so-called purified protein derivatives which are routinely used for skin tests. Preliminary experiments indicate the presence of antibodies against the 64-kDa antigen in sera from tuberculosis patients.

Dissection of Mycobacterium tuberculosis antigens using recombinant DNA

A recombinant DNA strategy has been used systematically to survey the Mycobacterium tuberculosis genome for sequences that encode specific antigens detected by monoclonal antibodies. M. tuberculosis genomic DNA fragments with randomly generated endpoints were used to construct a large lambda gt11 recombinant DNA expression library. Sufficient numbers of recombinants were produced to contain inserts whose endpoints occur at nearly every base pair in the pathogen genome. Protein antigens specified by linear segments of pathogen DNA and produced by the recombinant phage of Escherichia coli were screened with monoclonal antibody probes. This approach was coupled with an improved detection method for gene isolation using antibodies to clonally isolate DNA sequences that specify polypeptide components of M. tuberculosis. The methodology described here, which is applicable to other pathogens, offers possibilities for the development of more sensitive and specific immunodiagnostic and seroepidemiological tests for tuberculosis and, ultimately, for the development of more effective vaccines.

Acquired immunodeficiency syndrome in a heterosexual population in Zaire

38 patients with the acquired immunodeficiency syndrome (AIDS) were identified in Kinshasa, Zaire, during a 3 week period in 1983. The male to female ratio was 1.1:1. The annual case rate for Kinshasa was estimated to be at least 17 per 100 000. Opportunistic infections were diagnosed in 32 (84%) patients, disseminated Kaposi's sarcoma (KS) with opportunistic infection in 5 (13%), and disseminated KS alone in 1 patient. Immunological characteristics of these patients were as reported for cases in the USA and Europe, but immunological abnormalities were also found in 6 controls with infectious diseases but no symptoms of AIDS. Female AIDS cases were younger than male patients with AIDS (mean ages 28.4 vs 41.1 years, respectively), and were more often single (14/18 vs 2/20). Homosexuality, intravenous drug abuse, and blood transfusion did not appear to be risk factors in these patients. The findings of this study strongly argue that the situation in central Africa represents a new epidemiological setting for this worldwide disease--that of significant transmission in a large heterosexual population. Two instances of clusters of AIDS (not included in the above series) involving males and females with frequent heterosexual contact further implicate heterosexual transmission.

Acquired immunodeficiency syndrome with severe gastrointestinal manifestations in Haiti

29 patients (19 males and 10 females) in Haiti were diagnosed as having acquired immunodeficiency syndrome. Their clinical presentation was characterised by unexplained chronic diarrhoea, prolonged fever, extreme weight loss, anorexia, and severe infections. The infectious agents included: Candida albicans (27 patients), Mycobacterium tuberculosis (7 patients), Cryptosporidium (11 patients), Pneumocystis carinii (2 patients), cytomegalovirus (4 patients), and herpes virus (3 patients). In 1 woman Kaposi's sarcoma developed during the course of her disease. Immunological studies of 20 patients revealed profound cell-mediated immune deficiency with cutaneous anergy, marked decrease in the number of T helper cells, and impairment of lymphocyte proliferation. 18 patients died.