Reduction of IL-12 p40 production in activated monocytes after exposure to diesel exhaust particles

BACKGROUND: A reduction of IL-12 production by lung macrophages may partly explain the presumed adjuvant effect of diesel exhaust particles (DEP) in allergy and asthma. IL-12 stimulates T helper type 1 (Th1) lymphocytes, which inhibit Th2 cells via Th1-specific cytokines. The aim of this study was to investigate the influence of DEP on the production of IL-12 p40 in lipopolysaccharide (LPS)-activated monocytes. METHODS: The human monocytic cell line Mono-Mac-6 was stimulated with LPS (200 ng/ml) and grown with DEP (0-200 microg/ml) for 0, 6 or 24 h. IL-12 p40 and the pro-inflammatory cytokine TNF were analysed in the cell supernatants by ELISA and a cell assay, respectively. RESULTS: Levels of IL-12 p40 correlated inversely with the DEP exposure concentrations, whereas TNF increased in parallel to the DEP concentrations. At a DEP concentration of 200 microg/ml, the amount of IL-12 p40 was 35% of that observed without DEP. The corresponding TNF value was 230% of the control. Reduced viability, binding of cytokines to DEP or endotoxin in the DEP samples cannot fully explain the changes in the concentrations of these two cytokines. CONCLUSION: DEP seem to inhibit the production of IL-12 p40 and stimulate that of TNF in activated monocytes. This may partly explain the presumed adjuvant effect of DEP in atopy; by altering the Th1/Th2 balance via down-regulation of IL-12, the Th2 response characteristic of allergy and asthma may be favoured.     

Induction of phagocyte-stimulating and Th1-promoting cytokines by in vitro stimulation of human peripheral blood mononuclear cells with Streptococcus pneumoniae

Polymorphonuclear granulocytes, which provide a major defence against Streptococcus pneumoniae infections, are attracted to and activated by various cytokines. The aim of this study was to analyse the cytokine response of human peripheral blood mononuclear cells to stimulation with S. pneumoniae. Strains belonging to serogroups 4, 6, 14, 19 or 23, were isolated from nasopharynx, middle ear fluid, cerebrospinal fluid or blood. All strains induced a marked proliferative response of the peripheral blood mononuclear cells; the stimulatory index was 34+/-11. High levels of pro-inflammatory cytokines were induced, i.e. interleukin (IL)-1beta (53+/-25 ng/ml), IL-6 (347+/-41 ng/ml) and tumour necrosis factor (TNF)-alpha (15+/-4 ng/ml). Also, chemokines and immunoregulatory cytokines including IL-8 (215+/-224 ng/ml), IL-10 (122+/-60 pg/ml), IL-12 (1195+/-648 pg/ml), interferon (IFN)-gamma (18+/-4 ng/ml) and granulocyte macrophage colony-stimulating factor (135+/-80 pg/ml) were induced. Several of these cytokines can up-regulate phagocytosis and the killing of bacteria. Interestingly, strains isolated from middle ear fluid and blood elicited significantly fewer IL-8 and significantly more IL-12 and IL-10 than strains from nasopharynx. They also induced a stronger proliferative response. Our results indicate that pneumococci are potent inducers of cytokines, especially IL-12, favouring T-helper cell type 1 (Th1) responses.     

Use of robotized DNA isolation and real-time PCR to quantify and identify close correlation between levels of Neisseria meningitidis DNA and lipopolysaccharides in plasma and cerebrospinal fluid from patients with systemic meningococcal disease

The present study, using robotized DNA isolation and quantitative PCR based on the Neisseria meningitidis-specific capsular transport A gene, demonstrates the ease, rapidity, specificity, and sensitivity of quantifying neisserial DNA in plasma (n = 65) and cerebrospinal fluid (CSF) (n = 12) from patients with systemic meningococcal disease. We found a close correlation between the levels of neisserial DNA and lipopolysaccharides in plasma (r = 0.905) and in CSF (r = 0.964). The median concentration of neisserial DNA in plasma in 23 patients with persistent shock was 2 x 10(7) copies/ml, versus <10(3) copies/ml in 42 nonshock patients. Furthermore, quantitative PCR made possible estimates of the total number of meningococci in plasma, as opposed to conventional blood cultures, suggesting about 1,000 dead meningococci for every viable bacterium. Finally, with logistic regression analyses, neisserial DNA may predict a patient's disease severity and outcome at hospital admission. The number of meningococci in plasma and CSF appears to be the main determinant of the lipopolysaccharide levels, clinical presentation, and outcome.     

Serum hyaluronate levels reflect disease activity in experimetal arthritis models

Serum hyaluronate (HA) levels were measured in rats subjected to adjuvant or type II collagen induced arthritis. As the arthritic lesions developed, both models showed an increase in serum HA levels of approximately 5 times, from a baseline level of 61–126 ng/ml (range). Furthermore a positive correlation was found between HA level and arthritic score. The increase in HA was not related to metabolic impairment, as the half life of serum HA in adjuvant arthritic rats was similar to that of normal rats. Serum HA may thus serve as a useful variable for evaluation of the severity of experimental arthritis.     

Differences in adsorption of serum proteins and production of IL-1ra by human monocytes incubated in different tissue culture microtiter plates

In vitro cell culture models can be of great value in order to further analyze the regulatory mechanisms underlying the inappropriate function of the immune system in diseases such as autoimmunity and cancer. Cell culture conditions have to be well controlled in a way that they mirror the in vivo situation. The objective of this study was to compare tissue culture microtiter plates from different manufacturers with respect to their ability to support monokine production by human monocytes cultured in human serum. Tissue culture ware, made of polystyrene, undergoes treatment by the manufacturers to make the surface more suitable for culture of adherent cell populations. It is possible that quality differences in this treatment can lead to variations in protein binding properties and thereby influence the adherence and functional properties of monocytes. We measured spontaneous interleukin-1 receptor antagonist (IL-1ra) production by peripheral blood monocytes, cultured in human serum, in five different microtiter plates made for adherent cell culture. Culture in plates from two of the five manufacturers resulted in significantly lower amounts of secreted IL-1ra. IL-1ra release by human monocytes can be induced by adherent IgG cross-linking membrane receptors for the Fc part of IgG (FcgammaR). We found that reduced IL-1ra production coincided with a reduced capacity for binding of serum IgG in one case. Furthermore, this brand of microtiter plate also displayed the lowest level of adsorption of human albumin. We conclude that the protein adsorption properties of the plastic tissue culture ware have to be taken into consideration when assessing monokine production by human monocytes in vitro.     

The differential effect of lysolecithin on mycoplasmas and acholeplasmas

The cidal effect of lysolecithin on mycoplasmas and acholeplasmas was studied. Thirty-one mycoplasma strains and species were tested. The growth of all of them was inhibited by 250 g/ml of lysolecithin and the growth of most by 125 g/ml. T-mycoplasmas were as sensitive to lysolecithin as the other mycoplasmas tested. On the other hand, acholeplasmas were about four-fold less sensitive; several strains of the three acholeplasma species grew even in the presence of 500 g/ml of lysolecithin. Strain Squire of Bovine Group 6 was more susceptible to lysolecithin than the other non-sterol requiring strains tested and in this respect resembled the mycoplasmas. Mycoplasmas were found also to be more susceptible to lecithin than acholeplasmas. The influence of the serum and cholesterol content of the medium on the results of the tests is considered and the importance of maintaining standard conditions is stressed. The possibility of using the susceptibility of mycoplasmas and acholeplasmas to lysolecithin of distinguish between them is discussed. The different amounts of cholesterol in the cell membrane of the organisms of these families might account for the differences observed.     

Directly bone-anchored implants for fixation of aural epistheses

In cases of missing outer ears, generally, epistheses are attached to eye-glasses which gives insecure attachment and a fairly poor cosmetic result. A new method for stable episthesis attachment is being tested in Gothenburg, Sweden. Threaded, cylindrical titanium implants are inserted with a meticulous technique in the temporal bone of the patient. At the next stage, 3–4 months later, the implants are connected to abutments which are allowed to penetrate the skin, To these abutments a silicone episthesis is attached. Presently, 7 patients who had no outer ear because of congenital disorders, hereditary diseases or status post trauma or tumour surgery have been operated and followed for up to $\text{1}\text{2}$ have been no problems reported with the bone anchorage or the skin penetration.     

Jejunal endocrine tumour composed of somatostatin and gastrin cells and associated with duodenal ulcer disease

Summary A case of malignant endocrine tumour of the jejunum, associated with severe duodenal ulcer is described. The tumour and a local metastasis were examined by immunohistochemistry and found to contain abundant somatostatin-immunoreactive cells together with less numerous cells displaying gastrin immunoreactivity. This is to our knowledge the first case of intestinal somatostatinoma. The presence of gastrin cells in the tumour may explain the ulcer diathesis.