Increased levels of antibodies to IFN-gamma in human and experimental African trypanosomiasis

In African trypanosomiasis the occurrence of antibodies to interferon-gamma (IFN-gamma) was studied in both humans and experimental rats. Sera from patients infected with Trypanosoma brucei gambiense showed increased levels of antibodies to IFN-gamma as compared with controls from the same regions in Africa. In Sprague-Dawley rats infected with Trypanosoma brucei brucei an early appearance of IFN-gamma-producing spleen cells was observed, followed by an increase in levels of antibodies against IFN-gamma in the sera. Previously, IFN-gamma has been found to play a crucial role in trypanosome infections in rats by promoting proliferation of Trypanosoma brucei brucei. The appearance of antibodies to IFN-gamma in humans, as in rats, indicates that this cytokine is produced also in the human infection. Its parasitic growth-stimulating and pathophysiological effects on the organism may be reduced by the antibodies.

In vitro antibacterial activity of the new quinolone Bay y3118 against clinical isolates

The in vitro antibacterial activity of the new fluoroquinolone Bay y3118 against 609 clinical isolates was evaluated. Bay y3118 exhibited activity against a broad spectrum of organisms, including Gram-negative bacilli, Gram-positive cocci, mycobacteria. The activity of Bay y3118 was often superior to that of other quinolones. Against Gram-negative bacilli its activity was similar to that of ceftriaxone, cefotaxime, ceftazidime and imipenem except for Serratia marcescens, Klebsiella pneumoniae, Enterobacter spp. and Xanthomonas maltophilia, where its activity was superior. Gentamicin and piperacillin sometimes were less active. Bay y3118 was active against a large number of Gram-positive cocci. The fluoroquinolones tested were active against all the strains of Mycobacterium tuberculosis, but only Bay y3118 was effective against Mycobacterium avium.

Diagnosis of bronchopulmonary infections by quantification of microflora

The quantification of bacteria and fungi in sputum or bronchoaspirate is of clinical value for the diagnosis of respiratory tract infections. We have developed an easy method to count the micro-organisms in patients with respiratory tract infections. This consists of the quantification of micro-organisms by subsequent streakings of a calibrated loop on agar. The correlation between microbiological quantitative data and the clinical status of patients with lower respiratory tract infections is discussed. The data seem to indicate that certain bacteria present in sputum or bronchoaspirate above a certain concentration may be responsible for lower respiratory tract infections. In patients with immunological disorders or chronic pathologies even lower concentrations of micro-organisms in bronchial secretions probably are enough to cause infections. The advantage of this counting method of the microbic species from the respiratory tract consists of their quantification: thus we can attribute an etiological role to a high concentration of the germs, while micro-organisms at low concentrations are probably contaminants. By this method isolated colonies are obtained after 12-18 hours. The bacterial quantification, by respiratory samples examination of the same patient in the following days, allows us to evaluate the efficacy of antibacterial therapy, producing a reduction of bacterial concentration.

Persistence of human T cell lymphotropic virus type 1 (HTLV-1) sequences in peripheral blood mononuclear cells from patients with mycosis fungoides

Mycosis fungoides (MF) is a rare form of cutaneous T cell lymphoma suspected of having a viral etiology. As in adult T cell leukemia, the virus involved may be human T lymphotropic virus type 1 (HTLV-1). We cultured the peripheral blood mononuclear cells (PBMC) of 29 patients with MF HTLV-1 seronegative by enzyme-linked immunosorbent assay and Western blot. The presence of reverse transcriptase (RT) and p24 antigen was investigated in the concentrate supernatant of the culture. The DNA of all studied patients was submitted to polymerase chain reaction and Southern blot analysis using primers and probes recognizing the tax region of HTLV-1/2 and the pol region of HTLV-1. 10 of 29 patients were found positive to HTLV-1, whereas they were always negative to RT and p24. The same results were confirmed in double blind after 6 mo. Our findings suggest HTLV-1 may be involved in the etiology of MF, at least in certain cases.

A multicentre study: Staphylococcus and Enterococcus susceptibility to antibiotics

A multicentre study to evaluate the susceptibility of Gram-positive cocci isolated from clinical samples, was performed by six centres working in different areas of Italy. We examined 4,544 strains of Staphylococcus aureus, 4,381 strains of coagulase-negative staphylococci and 2,478 strains of enterococci. The following antibiotics were tested: penicillin G, ampicillin, amoxicillin, piperacillin, imipenem, oxacillin, ofloxacin, pefloxacin, ciprofloxacin, gentamicin, tobramycin, amikacin, netilmicin, rifampicin, clindamycin, tetracycline, cotrimoxazole, erythromycin, chloramphenicol, vancomycin and teicoplanin. Oxacillin-susceptible staphylococci confirmed their susceptibility to many other antimicrobial agents while oxacillin-resistant strains confirmed their multiple and frequent resistance to antibiotics. Resistance to oxacillin, cotrimoxazole and chloramphenicol was more frequent in coagulase-negative staphylococci than in Staphylococcus aureus. Aminoglycosides, rifampicin and quinolones were more active against coagulase-negative staphylococci than against Staphylococcus aureus. Enterococci were susceptible to penicillins and imipenem, and moderately susceptible to ciprofloxacin. Susceptibility of 70-79% was observed with high levels of aminoglycosides. Excellent results against staphylococci and enterococci were observed with vancomycin and teicoplanin.

Development of a flow cytometric assay for the detection and measurement of neutralizing antibodies against human immunodeficiency virus

Cells infected with human immunodeficiency virus type 1 (HIV-1) develop viral antigens which can be detected by immunofluorescence. We developed a flow cytometric immunofluorescence assay (FIFA) which provides a quantitative analysis of HIV-1 p24 using a monoclonal antibody (mAb) as a specific reagent. The reduction of HIV p24 antigen expression in viral infected cells was then used to determine HIV neutralizing antibody titers in human sera. Results obtained by FIFA for detecting neutralizing antibodies against HIV-1, when compared with results obtained by indirect immunofluorescence assay (IFA), showed an overall index of agreement of 94.1%. The correlation between the neutralizing antibody titers obtained with each method was found to be highly significant (ro = 0.8; p < 0.01). The simple methodology and the adaptability of this FIFA to various assay conditions make it suitable for routine purposes and for assessing the efficacy of vaccination strategies.

Flow cytometric indirect immunofluorescence assay with high sensitivity and specificity for the detection of antibodies to HSV-1 and HSV-2

Cells infected with HSV-1 or HSV-2 develop viral antigens which can be detected by immunofluorescence. We developed a flow cytometric indirect immunofluorescence assay to detect and quantitate antibodies to HSV-1 and HSV-2 in human sera. Results obtained by flow cytometry for detecting antibodies against HSV-1, when compared with results obtained by ELISA, showed an index of overall agreement of 100%. The correlation between the antibody titers obtained with each method was found to be highly significant. An index of overall agreement equal to 94.1% was observed between results obtained by flow cytometry and by immunofluorescence as concerns the discrimination of HSV-2 positive from negative samples. However, the correlation between antibody titers was found to be not statistically significant. The flow cytometric assay proved to be type-specific.

Rapid methods for microbial diagnosis of mycobacterial infections

The Authors describe their experience in rapid diagnosis of mycobacterial infections using a combination of a radiometric blood culture (Bactec 13 A) and a nucleic acid hybridization system (Gen probe, Accuprobe) to detect and identify Mycobacteria. They found out that a high number of septicaemias in HIV positive patients are due to Mycobacterium avium, while in HIV negative subjects Mycobacterium tuberculosis is the most frequent mycobacterium.

The role of human autoantibodies against gamma-interferon

Natural antibodies to gamma-interferon (IFN-gamma) were detected in the serum of viral infected patients and also in the serum of healthy subjects at a lower titre. The increased titres of antibodies to IFN-gamma in sera from viral infected patients, and their decrease with clinical resolution, indicates that these antibodies are related to the viral infection and probably reflect IFN-gamma production as a result of antigenic stimulation in vivo. These antibodies were affinity-purified and studied for their capability to interfere with the multiple activities of IFN-gamma in vitro. Data obtained show that human anti-IFN-gamma antibodies interfere with the immunomodulating activity but not with the antiviral and antiproliferative activity of lymphokine. Autoantibodies to IFN-gamma may have a role in the immunoregulatory process serving to limit the intensity and or duration of the immune response. Being able to interfere with the immunomodulating activities of IFN-gamma, these antibodies might open up new therapeutic possibilities for those diseases which carry evidence of activated cell-mediated immunity.

Expression of activation markers on peripheral-blood lymphocytes following oral administration of Bacillus subtilis spores

This study was undertaken to assess the capability of Bacillus subtilis spores to modify the peripheral-blood lymphocyte (PBL) subsets or determine the de novo expression of activation markers. The data we obtained show that spores of B. subtilis are able to increase the expression of certain cell activation markers and that such activation is dose-dependent. In fact, doses of 2 x 10(9) spores did not give rise to changes in any of the parameters evaluated, while doses of 6 x 10(9) increased the HLA-DR antigen expression on T-lymphocytes. At the highest dosage used (12 x 10(9), B. subtilis spores caused the appearance of cells bearing the CD25 and CD71 activation markers. Therefore, such cell activation markers may prove useful for monitoring the activity of B. subtilis spores, and possibly of other immunomodulating agents, in the course of clinical research.

High-titre antibodies to a foreign epitope elicited by affinity-purified hybrid LamB proteins

A monoclonal antibody to the LamB protein, named LBS-1, was developed and characterized. It was then covalently bound to Sepharose and used to purify hybrid LamB proteins from Escherichia coli crude extracts. A peptide of the interferon-gamma (IFN-gamma) NH2-terminal region, inserted within the LamB protein, was used as a model to assess immune response in mice injected with sonicated E. coli extract or with affinity-purified hybrid LamB protein. None of the mice immunized with the whole bacterial extract produced antibodies to IFN-gamma. On the other hand, all the mice immunized with the purified protein developed high-titre anti-IFN-gamma antibodies. These results might be due to the presence of bacterial components capable of masking the LamB protein to the immune system. The use of affinity-purified LamB proteins may constitute in some instances a more effective way of generating an immune response against foreign epitopes as opposed to whole bacterial antigens.

HTLV-1 sequences in lymphocytes of a patient with non-tropical spastic tetraparesis and her asymptomatic husband

We describe a 65-year-old woman born and living in Northern Italy affected by non tropical spastic tetraparesis and her asymptomatic husband presenting HTLV-1 sequences in their lymphocytes detected by polymerase chain reaction (PCR). We discuss the significance of the case and the mechanism involved in HTLV-1 infection and the relationship with neurological disorders, stressing that this case is the first reported in Italy.

New clinical data on the prophylaxis of infections in abdominal, gynecologic, and urologic surgery. Multicenter Study Group

Two dose schedules of the antibiotic cefotaxime were compared in a prospective, randomized 226-center study of 3,670 patients undergoing abdominal, gynecologic, and urologic surgery. Schedule A consisted of a single preoperative dose and schedule B consisted of one preoperative dose followed by two postoperative doses. There was no significant difference in the frequency of wound infection or bacteriuria between the two schedules. Schedule B was associated with a significantly higher incidence of postoperative pyrexia, further antibiotic therapy, local side effects, and extended hospital stay. One dose probably has less impact on the intestinal flora. Therefore, single-dose cefotaxime is as effective and less costly when compared with multiple-dose cefotaxime for common surgical procedures lasting less than 3 hours.

Natural human antibodies to gamma interferon interfere with the immunomodulating activity of the lymphokine

Natural antibodies to gamma interferon (IFN-gamma) were found in patients suffering from different viral diseases and, at a lower titer, in healthy individuals. Such antibodies were affinity-purified and studied for their capability to interfere in vitro with the antiviral and immunomodulating activity of IFN-gamma. Data obtained show that these human anti-IFN-gamma antibodies have no inhibitory effect on the antiviral activity of IFN-gamma. On the contrary, they are able to inhibit the expression of Fc receptor sites and HLA-DR antigens induced by IFN-gamma on the U-937 cells, a human monocytoid/macrophage-derived cell line. These antibodies can also interfere in a mixed lymphocyte culture (MLC) with the proliferation of lymphocytes and the generation of cytotoxic lymphocytes. However, they showed only a moderate inhibitory effect on the cytotoxicity generated in MLC to K-562 cells. Human antibodies capable of interfering with the immunomodulating activities of IFN-gamma might open up a new field in clinical therapy for those diseases that carry evidence of activated cell-mediated immunity.

Inhibition of the biological activity of human interferon-gamma by antipeptide antibodies

To study the domain(s) responsible for the different biological activities of human interferon-gamma (HuIFN-gamma), rabbits were immunized with peptides corresponding to the five most hydrophilic amino acid sequences of the lymphokine. The resulting antisera were able to recognize both the immunizing peptide and the native protein. Antibodies to the carboxy-terminal region (amino acids 125-137) of HuIFN-gamma were able to interfere with the immunomodulating, antiviral, and antiproliferative activities of the lymphokine. Inhibition of the antiproliferative and antiviral activity was also observed using antibodies raised against the amino-terminal region (amino acids 4-16) and amino acids 80-95, respectively, but to a lesser extent than that observed with antibodies to the carboxyl terminus. The capability of these antibody preparations to partially interfere with only one of the lymphokine's biological activities might be explained by a mechanism of steric hindrance. The use of polyclonal antibodies allowed us to limit the presence of epitopes responsible for recombinant (r)HuIFN-gamma biological activities to the carboxy-terminal region.

Purification of natural human IFN-gamma antibodies

Natural antibodies to interferon gamma (IFN-gamma) were found in patients suffering from various viral infections, but also at weak titers in healthy individuals. In the present study we describe a one-step chromatographic procedure for the purification of the anti-IFN-gamma antibodies from human Ig preparations, using a recombinant IFN-gamma-coupled Sepharose CL4B affinity column. The antibodies to IFN-gamma were eluted from the column using 3 different methods without loss of immunological activity. They were found to be Ig, mostly of the IgG1 subclass, and, in the biological assay, to be able to neutralize the de novo expression of Fc receptor sites induced by IFN-gamma on U937 cells.

Interferon-gamma marks activated T lymphocytes in AIDS patients

Lymphocytes expressing interferon-gamma (IFN-gamma) on their surface were evaluated in 61 patients, all IV drug abusers, infected with human immunodeficiency virus type 1 (HIV-1), and in 85 healthy subjects (61 of whom were blood donors and 24 HIV-1 seronegative IV drug abusers). Data obtained demonstrated that IFN-gamma-expressing T lymphocytes, mostly CD8+ cells, were present in HIV-1-infected patients, and that their percentage, always higher in HIV-1-infected patients than in healthy subjects (p less than or equal to 0.001), increased with progressive stages of HIV-1 infection. At the same time other markers of T-cell activation, namely interleukin-2 receptor (rIL-2), transferrin receptor, and HLA-DR were also found to be positive in some of the HIV-1-infected subjects. The presence in the HIV-1-infected patients of activated CD8+ T cells, which are resistant to HIV-1 infection, may suggest that these cells are able to respond to continuous and progressive viral expression (HIV or/and other viruses) and may be a component of the specific response to HIV-1.

A single dose of aztreonam in the prevention of urinary tract infections in elderly catheterized patients

We have compared the effects of aztreonam and placebo in the prevention of urinary tract infections (UTI) in elderly hospitalized patients who needed urethral catheterization. 162 patients (96 males, 66 females; age range 60-91 years) were randomly allocated to receive double-blind a single dose of aztreonam (2 g i.m. 80 patients) or placebo (4 ml lidocaine 2%, 82 patients) three hours before catheterization. All patients were followed-up for 7 days. Urine culture was performed before, at the first, third and seventh day of catheterization. At the end of follow-up 71/80 patients (88.7%) who received a single preventing dose of aztreonam had negative urine culture without clinical signs of UTI. On the contrary, in the group treated with placebo at the end of follow-up only 38/82 patients (46.3%) had negative urine without clinical signs of UTI. In conclusion, our data suggest that a single 2g i.m. dose of aztreonam is effective in preventing UTI in elderly patients needing indwelling urethral catheterization.

Antibacterial activity of the new carbapenem meropenem (SM-7338) against clinical isolates

The in vitro antibacterial activity of the new carbapenem antibiotic meropenem (SM-7338) against 567 clinical isolates was evaluated. SM-7338 exhibited activity against a broad spectrum of organisms, including aerobes and anaerobes, and was superior to the other beta-lactam drugs tested (piperacillin, cefotaxime, ceftazidime, ceftriaxone, cefoxitin). SM-7338 was more active than imipenem, gentamicin and amikacin against Enterobacter cloacae and Pseudomonas aeruginosa. SM-7338 was less potent than imipenem against staphylococci and enterococci, but the activity of the two antibiotics against anaerobes was similar. SM-7338 and imipenem showed a high bactericidal activity at a concentration of 2-4 x MIC.

Interferon-gamma is associated with the surface of the human immunodeficiency virus and binds to the gag gene product p17

Purified HIV-1 antigen preparations produced in cell culture were found to contain interferon-gamma (IFN-gamma). Electron microscopic examination of HIV-1 released by H9 cells, a cell line found to produce IFN-gamma, showed the presence of this molecule on the surface of the virus particle. The HIV-1 protein p17 was found to bind IFN-gamma by a solid-phase radioimmunoassay. The specificity of the reaction was confirmed by Western blot analysis. This finding opens new questions about the biologic role of IFN-gamma itself and of its interaction with HIV.

Antigen capture ELISA for HTLV I in cell culture

Recent reports have shown that HTLV I infection is widespread and that HIV/HTLV I combined infections may accelerate the progression of seropositive patients towards AIDS. In order to obtain a tool for the detection and identification of HTLV I in cell culture we have developed an antigen-capture ELISA, which is based on the use of rabbit hyperimmune serum on solid phase and mouse monoclonal antibodies against p19 and p24 as tracers. This assay has a sensitivity of 50 ng/ml, it can be used to test cell-culture fluids and does not cross-react with any other known human retroviruses.