HIV-1-related pleural tuberculosis: elevated production of IFN-gamma, but failure of immunity to Mycobacterium tuberculosis.

BACKGROUND: Pleural tuberculosis can resolve spontaneously, suggesting that the inflammatory process may represent a protective immune response. However, pleural tuberculosis is strongly associated with HIV infection. It has been suggested that cell-mediated immune responses may be reduced, and direct bacterial invasion may have a role in pathogenesis, in HIV-positive cases. To test this hypothesis, we compared production of the pro-inflammatory cytokines, interferon (IFN)-gamma and tumour necrosis factor(TNF)-alpha, production of the immunosuppressive cytokine, interleukin (IL)-10, and mycobacterial culture positivity, in HIV-negative and HIV-positive patients with pleural tuberculosis. METHODS: Cytokine levels were measured in serum and pleural fluid, and in supernatants of blood and pleural fluid stimulated in vitro using mycobacterial antigens. Intracellular IFN-gamma and TNF-alpha production was measured after stimulation with phorbol myristate acetate and ionomycin in vitro. RESULTS: IFN-gamma was strikingly elevated in serum and pleural fluid in HIV-positive, compared to HIV-negative subjects (P < or = 0.02). TNF-alpha was elevated, but this was not statistically significant. IL-10 levels were higher in serum (P < 0.001), but similar in pleural fluid. IFN-gamma responses to soluble mycobacterial antigen in vitro were reduced in peripheral blood (P = 0.006), but not pleural fluid, of HIV-positive subjects. Intracellular cytokine staining suggested that CD8+ T cells were a major source of IFN-gamma in HIV-positive subjects. The proportion of subjects with a positive culture for Mycobacterium tuberculosis from pleural fluid was higher in the HIV-positive group. CONCLUSIONS: HIV-positive patients with pleural tuberculosis show elevated production of IFN-gamma, for which CD8+ T cells may be a major source. Mycobacterium tuberculosis can proliferate despite high levels of pro-inflammatory cytokines.

Diurnal stability of refraction after implantation with intracorneal ring segments.

PURPOSE: To investigate diurnal changes in visual acuity and refraction in myopic eyes implanted with intracorneal ring segments (ICRS). SETTING: University of California San Diego Shiley Eye Center, La Jolla, California, and Emory University Vision Correction Center, Atlanta, Georgia, USA. METHODS: This prospective study involved 2 groups of patients who had ICRS (Intacs) implantation and a follow-up of at least 6 months. The first group included 102 eyes of 51 bilaterally treated patients; the second group, 32 eyes of 16 unilaterally treated patients. Examinations including visual acuity, manifest refraction, and videokeratography were done in the morning and evening at least 9 hours apart on a single day. Refractive changes were analyzed by power vectors; multivariate statistics were used to determine the significance of change in any component of the spectacle prescription. RESULTS: In the bilateral treatment group, 97 eyes (95%) were within 1 line of spectacle-corrected visual acuity from morning to evening. The mean change in manifest refraction was -0.14 +0.08 x 4 and in spherical equivalent, -0.10 diopters (D) (sigma = 0.3; range -0.750 to +0.875 D). Ninety-six eyes (94%) had a change in refraction within 0.50 D of spherical equivalent. There was no significant change in corneal power (P =.20). In the unilateral treatment group, there was no significant difference between treated and untreated eyes in changes in spectacle-corrected visual acuity, manifest refraction, or corneal power and toricity (P.05). CONCLUSION: No clinically significant diurnal variation in visual acuity or manifest refraction was observed after ICRS implantation or in untreated paired eyes. Moreover, the data suggest less diurnal change in visual acuity and refraction after ICRS implantation.

The immune response to Mycobacterium tuberculosis in HIV-infected and uninfected adults in Uganda: application of a whole blood cytokine assay in an epidemiological study.

SETTING: Out-patient clinic, Entebbe, Uganda. BACKGROUND: It has been proposed that 'type 1' cytokines are essential in protective immunity to Mycobacterium tuberculosis and that suppression of 'type 1' or a switch to a 'type 2' profile is deleterious. We employed a simple assay to examine whether the dependence of the immunological responses to mycobacterial antigens on a range of explanatory factors could be determined in a population where tuberculosis is endemic. OBJECTIVE: To determine the relationship between the tuberculin skin test response and cytokine profile, and the effect of human immunodeficiency virus (HIV) infection. DESIGN: A cross-sectional study of 97 Ugandan adults (22 HIV-positive, 75 HIV-negative). Whole blood was stimulated in vitro using mycobacterial antigens (purified protein derivative [PPD] and culture filtrate proteins [CFP]). 'Type 1' cytokines (gamma interferon [IFN-gamma] and interleukin-2 [IL-2]), 'type 2' cytokines (IL-5 and IL-10) and tumour necrosis factor alpha (TNF-alpha) were measured in culture supernatants. RESULTS: Among HIV-negative subjects, a positive tuberculin skin test was associated with type 1 or mixed (type 1 + type 2) cytokine production, but a positive IFN-gamma response also occurred in a proportion of tuberculin skin test negative subjects (36% for PPD, 17% for CFP). In association with HIV infection, IFN-gamma responses to mycobacterial antigens were profoundly impaired (odds ratio [OR] 0.10 for PPD, 0.06 for CFP, P< or =0.001), but production of IL-2, IL-5 and TNF-alpha was relatively sustained, and IL-10 increased or sustained (OR 3.97 for PPD, P = 0.01, 1.14 for CFP, P = 0.99). CONCLUSION: The type 1/type 2 cytokine balance was not defined by the tuberculin skin test response, and may have a closer relation to protective immunity. IFN-gamma production was strikingly impaired in association with HIV infection, while production of type 2 cytokines was sustained or increased. Use of a simple assay allowed a large sample of subjects to be examined, producing epidemiologically meaningful results.

Elevated opsonic activity for Porphyromonas (Bacteroides) gingivalis in serum from patients with a history of destructive periodontal disease. A case: control study.

We have measured the opsonic capacity of serum for the phagocytosis of Porphyromonas (Bacteroides) gingivalis by polymorphonuclear leucocytes (PMN) in 35 patients with a history of destructive periodontitis and 35 matched control subjects. The serum from cases, tested at concentrations of 8% and 0.8% opsonised P. gingivalis for phagocytosis by PMN to a level significantly greater than controls (p < 0.0001 and < 0.01 respectively). IgG antibody levels to P. gingivalis whole cells estimated by ELISA were also significantly higher in the cases (p < 0.0001). The IgG antibody levels correlated significantly with the opsonic capacity of the serum tested at 8% concentration in controls (r = 0.371, p = 0.03) but not in cases (r = 0.235, p = 0.17); in 0.8% serum, the opsonic capacity of the cases and controls were not significantly correlated. Elevated opsonisation by serum was a significant predictor that a subject was a case rather than a control, even after allowing for the effect of elevated IgG antibody in the cases. The data suggest that an elevated capacity of serum to opsonise P. gingivalis is a distinctive feature in patients with past destructive periodontal disease.

Inhibition of polymorphonuclear leucocyte phagocytosis by Porphyromonas gingivalis culture products in patients with adult periodontitis.

Porphyromonas gingivalis culture products and a purified trypsin-like protease (TLPase) from the organism were tested for their effects on the phagocytosis of P. gingivalis by polymorphonuclear leucocytes (PMN) from 16 patients with adult periodontitis and 16 healthy subjects in a case-control study. Both the culture products (p < 0.0001) and the TLPase (p < 0.0001) significantly inhibited PMN phagocytosis by both case and control samples. Culture products were significantly more inhibitory in both cases (p < 0.0019) and controls (p < 0.0198) than that TLPase. The case PMNs were significantly more susceptible to inhibition by culture products than the control PMNs (p < 0.0238). The data suggest that patients with adult periodontitis have PMNs that are more susceptible than normal to the inhibitory effects of P. gingivalis and might be at greater risk than healthy subjects to infection by this pathogen.

Interleukin-1 beta and IgG subclass concentrations in gingival crevicular fluid from patients with adult periodontitis.

Interleukin-1 beta (IL-1 beta) and the four IgG subclasses were measured in gingival crevicular fluid (GCF) at 35 sites in 19 patients with adult periodontitis. Serum concentrations of the IgG subclasses were assayed in 16 patients. IL-1 beta was detected in GCF at 88.6% of sites at concentrations ranging from 12.38-420.90 pg/microliters (mean 138.35 +/- 112.61 pg/microliters). IgG1 was detected at 81.2% sites, IgG2 at 93.6%, IgG3 at 71% and IgG4 at 71%. Absolute concentrations in GCF were: IgG1--2.419 g/l +/- (SD) 3.389; IgG2--2.945 +/- 6.434; IgG3--0.118 +/- 0.144; IgG4 0.864 +/- 1.336. There were no significant correlations between IL-1 beta concentrations, GCF volume or the clinical status of the sample site. IL-1 beta was not correlated with any of the IgG subclasses. The absolute concentrations of all subclasses in GCF were significantly negatively correlated with GCF volume and positively correlated with the Bleeding Index. Only IgG4 was significantly negatively correlated with the probeable crevice depth index. The concentration of each IgG subclass was positively correlated with the other three IgG subclasses. Subclass concentrations in GCF, relative to serum concentrations, were not correlated with GCF volume or clinical status. Relative concentrations of IgG1, IgG2 and IgG3 showed significant positive correlation with each absolute concentration of the other subclasses but IgG4 did not show this relation. It was concluded that IL-1 beta is not related to clinical measurements of inflammation or previous attachment loss. The data suggest that IgG in GCF is largely derived from plasma but that some IgG4 may be locally synthesized.

IgG subclass antibodies to Porphyromonas gingivalis in patients with destructive periodontal disease. A case: control study.

We have estimated by ELISA the levels of IgG subclass antibodies against P. gingivalis strain W83 whole cells in 35 cases of adult periodontitis and 35 age, sex, ethnic origin and plaque index-matched healthy controls. The mean levels of IgG1 (p < 0.0003) and IgG2 (p < 0.0416) were significantly elevated in the cases. Many sera had no detectable IgG4 antibodies but by categorising IgG4 responses into high, low and absent, this subclass was more often present (p < 0.002) in the cases. Analysis of the paired differences between cases and controls showed that only IgG1 (p < 0.0005) and IgG4 (p < 0.003) levels were significantly greater in the cases. The data support the role of P. gingivalis as a key pathogen in adult periodontitis and high levels of IgG4 antibodies might possibly provide a marker of patients with active disease.

Elevated levels of the IgG2 subclass in serum from patients with a history of destructive periodontal disease. A case-control study.

The levels of the 4 subclasses of IgG were estimated in the serum from 35 patients with a history of chronic periodontitis and 35 matched controls. The levels of IgG2 were significantly (P less than 0.019) elevated in the patients (3.756 g l-1) compared to the controls (2.882 g l-1). The data suggest that the predominant antibody response to periodontal pathogens in periodontitis may be directed against carbohydrate or glycolipid antigens.

Phagocytosis of Porphyromonas gingivalis and Prevotella intermedia by human polymorphonuclear leukocytes in clots formed from human plasma or purified fibrinogen.

We have studied the polymorphonuclear leukocyte (PMN) phagocytosis of Porphyromonas gingivalis (Bacteroides gingivalis) and Prevotella intermedia (Bacteroides intermedius) in three-dimensional fibrin meshworks formed by either clotting human plasma or by clotting purified fibrinogen with human serum incorporated. PMN phagocytosis of rhodamine isothiocyanate-labelled P. gingivalis in the fibrinogen clot was 43 +/- 6% and in the plasma clot was 62 +/- 10%; for P. intermedia the values were 15 +/- 10% and 63 +/- 10%, respectively. This showed that phagocytosis in the plasma clot system was significantly higher than in the fibrinogen clot system. However, increasing the concentration of serum in the fibrinogen clot abolished this difference, suggesting that opsonin levels determine PMN function in this assay. Labelling the bacteria with a different fluorochrome, fluoroscein isothiocyanate, reduced the level of PMN phagocytosis in both three-dimensional systems but phagocytosis was unaffected when PMN were adherent to glass. It would appear that PMN phagocytosis in three-dimensional systems can vary depending on the composition of the clot and the fluorochrome used to label the bacteria.

Effects of Porphyromonas gingivalis culture products on human polymorphonuclear leukocyte function.

Porphyromonas gingivalis culture supernate was found to induce homotypic agglutination of human polymorphonuclear leukocytes (PMN). Pretreatment of PMN with P. gingivalis supernate inhibited both the rate and the degree of agglutination induced by the secretagogues PMA and FMLP. Lipopolysaccharide from P. gingivalis upregulated the CR3 (Mac-1, CD11b) receptors on PMN. Treatment of glass-adherent PMN with P. gingivalis supernate did not alter their phagocytic capacity for P. gingivalis cells but when PMN were pretreated in suspension the cells adhered less well to glass and phagocytosis of those PMN that did adhere was reduced. P. gingivalis supernate treatment of PMN induced lysozyme release but the amount released during phagocytosis when supernate was present did not change. Neither P. gingivalis supernate nor LPS were cytotoxic for PMN. The data suggest that P. gingivalis factors could interfere with PMN elimination of this organism at the site of infection by inappropriately stimulating PMN, depressing phagocytosis and causing enhanced CR3 expression. The consequent agglutination or enhanced adherence could also lead to decreased phagocytic capacity of the adherent or agglutinated cells.

Polymorphonuclear leukocyte phagocytosis of Capnocytophaga ochracea in three-dimensional plasma clots.

We have studied the ability of human polymorphonuclear leukocytes (PMN) to phagocytose Capnocytophaga ochracea in three-dimensional fibrin meshworks. Phagocytosis was assessed in three systems: (1) the PMN and bacteria were mixed together with plasma and clotted; 60 +/- 13% phagocytosis occurred after 60 min; (2) PMN were overlaid on clots containing bacteria; the PMN migrated into the clot and after 60 min 52 +/- 7% phagocytosis was seen; (3) PMN had to migrate from within one clot into a second containing bacteria; phagocytosis after 60 min was 54 +/- 3%. In the clots, PMN released lysozyme but this was not significantly enhanced by phagocytosis. These findings indicate that PMN are capable of phagocytosing in each of the three-dimensional systems tested and that they are capable of both migration into and subsequent phagocytosis in a model that more closely mimics the in vivo structure in which PMN would normally perform.