Clinical aspects of delta infection.

The clinical features of delta infection were analysed retrospectively in 191 hepatitis B surface antigen (HBsAg) carriers and 592 cases of acute hepatitis B seen over 11 years in the Swedish town of Malmö (population 250 000). With a few exceptions delta infections occurred exclusively in drug addicts. In the chronic HBsAg-carriers the most common clinical manifestation was an episode of acute hepatitis, which in some individuals became severe with a pronounced rise in serum alanine aminotransferase activity for many months. During the period of delta infection the HBsAg titre was lowered and in three out of 26 cases the patient lost HBsAg altogether and developed hepatitis B surface antibodies (anti-HBs). In one patient the acute hepatitis due to delta infection was fulminant and fatal. In patients with acute hepatitis B the clinical picture did not distinguish between those with and without simultaneous delta infection. The frequency with which acute hepatitis B was succeeded by a chronic carrier state was the same whether or not the patient was infected simultaneously with the delta agent. The discovery of the delta agent has improved understanding of the natural history of chronic hepatitis B infection in drug addicts. Thus, instances of acute hepatitis in a chronic carrier, previously termed hepatitis non-A, non-B, may actually be episodes of delta infection.     

Clinical aspects and pathogenesis of Candida infection

The Interdisciplinary Forum on Candidosis, organized by the DGHM section Eukaryotic Pathogens, was held at the University of Würzburg, Germany, 17–18 April 1998.     

Antibodies against BCG antigen 60 in mycobacterial infection.

A sensitive specific radioimmunoassay was developed to measure antibodies against BCG antigen 60, a prominent antigenic component of BCG bacilli which cross-reacts with similar components in many mycobacterial species including Mycobacterium leprae and M tuberculosis. A lepromatous serum pool had anti-BCG-60 activity with a titre of 10(5) and the tuberculoid pool a titre of 10(4). Testing of individual sera showed striking variations within groups of patients with lepromatous and tuberculoid leprosy. In five of the 20 tuberculoid leprosy sera the anti-BCG-60 activity was above the median for the lepromatous group. The current view that antibody formation against mycobacterial antigens is very low in tuberculoid leprosy thus no longer appears to be tenable. Sera from eight patients with active pulmonary tuberculosis also showed a striking variation in anti-BCG-60 content, and the median value of this group was even higher than in those with lepromatous leprosy.     

In vivo modulation of atypical mycobacterial infection: adjuvant therapy increases resistance to Mycobacterium avium by enhancing macrophage effector functions

Susceptible BALB/c mice were infected iv with a strain of Mycobacterium avium and infused with different biological response modifiers (BRM) in a gel delivery system so as to modify the progression of the infection in a beneficial fashion. Infusion of IL-2 or IL-4 in hydrophobic gels led to no significant enhancement of resistance. Infusion of muramyl dipeptide in hypromellose led to a significant enhancement of resistance against the M. avium, as seen by a significant reduction of colony-forming units (CFU) in the spleens of infected mice. Similarly, infusion of interleukin-1 beta in hypromellose in infected mice led to a significant reduction in CFU counts in the organs of mice. The mechanism(s) responsible for this enhanced resistance was studied further. It was found that infected mice developed profound immunosuppression, as judged by mitogenic and antigenic stimulation. Mice infused with MDP/hypromellose developed a similar immuno-suppression, suggesting that this adjuvant immunotherapy did not act by stimulating a T-cell response or by abrogating a putative suppressive phenomenon. Macrophages from mice infused with MDP alone were no more bacteriostatic for a virulent M. avium than control cells. However, macrophages from infected mice infused with MDP/hypromellose were more bacteriostatic for M. avium than cells from mice infected with M. avium and infused with the hydrophobic gel only. Overall, these results suggest that adjuvant immunotherapy is beneficial in M. avium infections.     

The evolution of immunosuppressive cell populations in experimental mycobacterial infection.

Immunosuppressor activity of considerable potency and complexity was generated during the course of chronic, progressive infection of C3H/Anf mice by Mycobacterium lepraemurium. From the 5th through 10th week after inoculation, spleen cells from infected mice mildly but reproducibly suppressed the direct plaque-forming cell response of normal spleen cell cultures to sheep erythrocytes. Suppression at this stage of infection was mediated by cells with macrophage-like characteristics. A marked increase in splenic suppressor activity at 10 to 11 weeks was associated with the appearance of a second suppressor cell subpopulation composed of T lymphocytes. The appearance of these cells was closely related in time to the onset of rapid splenic enlargement and a loss of cutaneous delayed type hypersensitivity to antigens of M. lepraemurium in mice at 10 to 11 weeks of infection. Suppressor cells were not present in peripheral lymph nodes until terminal infection at 22 to 25 weeks. Suppressor spleen cells depressed the T-dependent antibody response most severely, but there was also a direct effect upon B cells as shown by moderate suppression of responses to TNP-LPS and DNP-Ficoll. Spleen cells from 14-week-infected mice generated a soluble suppressor factor(s) that induces depression of moderate severity, however, the immunosuppression by intact cells was far greater.     

The role of cytokines in mycobacterial infection

Mycobacterial infections are a major cause of morbidity and mortality worldwide. The pathogenesis of infection and the mechanisms for the development of protective immunity are poorly known, but cytokines appear to play an important role in the modulation of the immune response. Evidence exists for the role of tumor necrosis factor (TNF-), granulocyte macrophage colony stimulating factor (GM-CSF) and interferon-gamma (IFN-) in the host defense against mycobacteria. In this article we discuss recent findings about the role of cytokines in leprosy, tuberculosis andMycobacterium avium infection, usingin vitro andin vivo human and murine data.Abbreviations M.TB Mycobacterium tuberculois - IFN- interferon gamma - TNF- tumor necrosis factor-alpha - LAM Lipoarabinomannam - IL-8 Interleukin-8 - IL-6 Interleukin-6 - IL-2 Interleukin-2 - CMI cell-mediated immunity - PPD purified protein derivative of tuberculin - MAC Mycobacterium avium complex - AIDS Acquired Immunodeficiency Syndrome - GM-CSF granulocyte macrophage colony stimulating factor - IL-10 Interleukin-10 - TGF transforming growth factor ₁     

Clinical aspects of cytomegalovirus infection after allogenic bone marrow grafts

CMV infection is one of the major infection after bone marrow transplantation. CMV viremia was systematically studied in 66 patients with aplastic anemia or leukemia undergoing BMT. 57% patients had CMV viremia with a frequency peak between 7 and 9 weeks after transplant. Clinical symptoms found during viremia were pancytopenia, fever, cytolytic hepatitis. Interstitial pneumonitis was found only in 4 cases. In 3 cases, viremia was not associated with clinical symptoms. Survival was identical to the group of patients without viremia. Viremia was positively associated with the presence of high anti-CMV antibody titer in donor or recipient before transplant, or to a lymphocyte proliferative response against CMV antigens in donor or recipient before BMT. Granulocyte transfusions increased the frequency of CMV viremia. CMV infection was significantly associated with acute and chronic graft versus host disease. The relation showed between these parameters and viremia provides a basis for an accurate diagnosis of CMV infection and a better background for the study of prophylactic or curative treatment of CMV infection.     

Clinical and biological aspects of infection caused by Ehrlichia chaffeensis

Ehrlichia chaffeensis is an obligatory intracellular bacterium that infects the monocyte-macrophage. E. chaffeensis, which is transmitted to humans by ticks primarily from infected deer, causes human monocytic ehrlichiosis, an acute febrile systemic illness. This paper reviews current knowledge of clinical and biological aspects of infections caused by E. chaffeensis.     

Immunological aspects of Helicobacter pylori infection.

Host defence against Helicobacter pylori infection is a complex system of both specific and non-specific reactions. Among the non-specific defense mechanisms acting on bacteria before they reach the mucus layer in the stomach are digestive enzymes, lyzozyme, lactoferrin and other components with antimicrobal activity. The mucus layer is the final non-specific barrier against the bacteria reaching the gastric mucosa cells. On reaching the gastric mucosa Helicobacter pylori adheres to epithelial cells and bacterial antigens, chemotaxins and other components are liberated. Helicobacter pylori antigens are presented to immunate B lymphocytes, which interact with T-helper lymphocytes to become mature IgA-, IgD-, IgE-, IgG and Ig-M producing plasma cells. IgA dimers of secretory IgA are secreted through the gastric epithelium. IgE antibodies bind to basophils, which mature to histamine-producing mast cells. Histamine activates the acid production in the stomach and contributes to the chronic inflammation and tissue destruction. In addition, T lymphocytes are possible activated by Helicobacter pylori and contribute to the chronic inflammation.     

Genetic heterogeneity of Mendelian susceptibility to mycobacterial infection

Mendelian susceptibility to poorly virulent mycobacterial species, such as bacillus Calmette-Guérin (BCG) and environmental nontuberculous mycobacteria (NTM), is a phenotypically heterogeneous syndrome. It has therefore long been suspected to be genetically heterogeneous. In the past 5 years, this prediction has been confirmed and different types of mutations (dominant or recessive, nonfunctional or hypofunctional) in four genes (IFNGR1, IFNGR2, IL12B, IL12RB1) have revealed both allelic and nonallelic heterogeneity. The eight disorders resulting from these mutations are genetically different but immunologically related, as impaired IFN-gamma-mediated immunity is the common pathogenic mechanism accounting for mycobacterial infection in all patients. The severity of the phenotype depends on the genotype. Complete IFN-gammaR1 and IFN-gammaR2 deficiencies predispose patients to a more severe clinical course than partial IFN-gammaR1 and IFN-gammaR2 deficiencies and complete IL-12 p40 and IL-12Rbeta1 deficiencies.     

Bactericidal activity of alkaline glutaraldehyde solution against a number of atypical mycobacterial species

The mycobactericidal activity of 2% alkaline glutaraldehyde solution was determined using standardized suspensions of 10 species of atypical mycobacteria and compared with that for virulent Mycobacterium tuberculosis. Suspensions of M. avium, M. intracellulare and M. gordonae were more resistant to disinfection by the glutaraldehyde than were virulent tubercle bacilli while M. kansasii, M. scrofulaceum and M. szulgae were somewhat more susceptible. Mycobacterium marinum, M. smegmatis and M. fortuitum were highly sensitive to the disinfectant action of the alkaline glutaraldehyde solution. This variation in sensitivity shown by apparently closely related strains of mycobacteria to this disinfectant has important practical implications.     

Clinical aspects of ECL-cell abnormalities.

ECL cell hyperplasia results from hypergastrinemia, and in man this occurs due to achlorhydria in atrophic gastritis (pernicious anemia [PA]) and gastrinoma (Zollinger-Ellison syndrome [ZES]). Progression to neoplasia, i.e., ECL cell carcinoids (usually small, multicentric and non-functional), occurs in some five to 10 percent of patients with PA where they remain gastrin-dependent and reversible by normalization of serum gastrin by antrectomy. Even if untreated, the carcinoids are almost invariably benign and do not cause death. In ZES, ECL cell hyperplasia is progressive due to hypergastrinemia. However, carcinoids develop only in the MEN-I subtype but pose no additional threat of malignancy. A conservative approach is recommended for small multicentric carcinoids, and the tumors do not need removal. By contrast, single, large, non-gastrin-dependent carcinoids represent a different biological and clinical problem and are frequently malignant.     

Bactericidal activity of alkaline glutaraldehyde solution against a number of atypical mycobacterial species

The mycobactericidal activity of 2% alkaline glutaraldehyde solution was determined using standardized suspensions of 10 species of atypical mycobacteria and compared with that for virulent Mycobacterium tuberculosis. Suspensions of M. avium, M. intracellulare and M. gordonae were more resistant to disinfection by the glutaraldehyde than were virulent tubercle bacilli while M. kansasii, M. scrofulaceum and M. szulgae were somewhat more susceptible. Mycobacterium marinum, M. smegmatis and M. fortuitum were highly sensitive to the disinfectant action of the alkaline glutaraldehyde solution. This variation in sensitivity shown by apparently closely related strains of mycobacteria to this disinfectant has important practical implications.