CHARACTERIZATION OF LEPROSY SERA WITH VARIOUS MYCOBACTERIAL ANTIGENS USING DOUBLE DIFFUSION-IN-GEL ANALYSIS. A PRELIMINARY REPORT

HIV-associated immune complex kidney disease

The introduction in the late 20(th) century of combination antiretroviral therapy (cART) to treat patients infected with HIV has changed the natural history of the disease from an acute illness that rapidly culminates in death, to a chronic condition that can be managed with medications. Over the past decade the epidemiology of kidney disease in US patients infected with HIV has changed, perhaps because of the increased availability and use of cART. Patients with HIV infection exhibit unique immunologic characteristics, including immunodeficiency and dysregulation of immunoglobulin synthetic responses and T-cell function, which can result in glomerular immune complex deposition and subsequent kidney injury. This Review examines the differential diagnoses of HIV-associated immune complex kidney diseases (HIVICD), and discusses the clinical manifestations and mechanisms underlying their development. We address the issues associated with treatment, clinical outcomes, and research needs to enhance our ability to diagnose and optimally treat patients with HIVICD.

Signature-tagged mutagenesis of Klebsiella pneumoniae to identify genes that influence biofilm formation on extracellular matrix material

Klebsiella pneumoniae causes urinary tract infections, respiratory tract infections, and septicemia in susceptible individuals. Strains of Klebsiella frequently produce extended-spectrum beta-lactamases, and infections with these strains can lead to relatively high mortality rates (approximately 15%). Other virulence factors include production of an antiphagocytic capsule and outer membrane lipopolysaccharide (LPS), which mediates serum resistance, as well as fimbriae on the surface of the bacteria. Type 1 fimbriae mediate adherence to many types of epithelial cells and may facilitate adherence of the bacteria to the bladder epithelium. Type 3 fimbriae can bind in vitro to the extracellular matrix of urinary and respiratory tissues, suggesting that they mediate binding to damaged epithelial surfaces. In addition, type 3 fimbriae are required for biofilm formation by Klebsiella pneumoniae on plastics and human extracellular matrix; thus, they may facilitate the formation of treatment-resistant biofilm on indwelling plastic devices, such as catheters and endotracheal tubing. The presence of these devices may cause tissue damage, allowing Klebsiella to grow as a biofilm on exposed tissue basement membrane components. Though in vivo biofilm growth may be an important step in the infection process, little is known about the genetic factors required for biofilm formation by Klebsiella pneumoniae. Thus, we performed signature-tagged mutagenesis to identify factors produced by K. pneumoniae strain 43816 that are required for biofilm formation. We identified mutations in the cps capsule gene cluster, previously unidentified transcriptional regulators, fimbrial, and sugar phosphotransferase homologues, as well as genetic loci of unknown function, that affect biofilm formation.

Studies on the antigenic specificity of Mycobacterium leprae. II. Immunological characterization

Antigens from untreated and autoclaved Mycobacterium leprae obtained through chromatofocusing were tested for their ability to both induce as well as elicit skin reactivity in guinea pigs sensitized either with homologous and heterologous mycobacteria or with the fractions derived from autoclaved M. leprae. In former studies, of the several antigen-positive fractions, one showed specific activity and the remaining others cross-reactivity, as indicated by studies of hypersensitivity. The fraction exhibiting specificity contained only one antigen, whereas the other fractions contained more than one antigen. Because of the technique employed, all the fractions contained antigens that were proteinic in nature. In the latter studies, the antigens obtained from autoclaved M. leprae were shown to possess sensitizing capabilities, in addition to induction properties. Two fractions from untreated M. leprae had antigens that were heat-labile, whereas the remaining fractions contained heat-stable antigens.

Suppression of the antibody response to sulfolipids in leprosy patients by 4,4'-diaminodiphenyl sulfone (DDS)

Antibodies to sulfolipids were demonstrated in patients suffering from lepromatous leprosy. The antibody titre was found to decrease gradually on treatment with DDS. This effect was maximum for patients undergoing treatment for more than 1 year.

Mycobacterial polysaccharides. II. Comparison of polysaccharides from strains of four species of mycobacteria

Evidence from chemical and serological studies indicates that a cellular heteropolysaccharide, also found in lipid extracts and culture filtrate, is present as a group antigen in Mycobacterium tuberculosis H37Ra and in other strains of mycobacteria representing M. kansasii, scotochromogenic and Battey strains. Polysaccharides from the four strains contain the same main sugars, arabinose, and galactose, as revealed by thin-layer chromatography and spectrophotometric studies. In Ouchterlony gel diffusions, bands of identity are produced between the polysaccharides by using rabbit antiserum prepared against any of the four mycobacteria. Immune adsorption studies also confirm the presence of identical antigenic determinant groups. In skin tests with tuberculopolysaccharide I, a skin reaction of about equal size was elicited in guinea pigs sensitized with either M. tuberculosis H37Ra or heterologous mycobacterial antigens in Freund's incomplete adjuvant. In animals sensitized with M. tuberculosis H37Ra, skin tests with both homologous and heterologous polysaccharides elicited similar responses.

Chemical and serological relationships between the heteropolysaccharides of Mycobacterium tuberculosis and Mycobacterium kansasii

The identity of a heteropolysaccharide from cell walls of Mycobacterium tuberculosis H37Ra with Seibert's tuberculopolysaccharide I was demonstrated by thin-layer chromatography, chemical analysis, and antigenic tests. The polysaccharide of M. kansasii was shown to be identical with that of M. tuberculosis. Defatted cells were disintegrated by ultrasonic treatment in the presence of glass beads; cell walls were obtained by differential ultracentrifugation. Ethyl alcohol-precipitated carbohydrate extracts were analyzed for protein and nucleic acid; these impurities were removed. Tuberculopolysaccharide I from the mycobacterial culture filtrate is probably derived from a lipopolysaccharide of the cell wall, which is partially removed by chloroform in the intact state. Alkaline extraction releases additional polysaccharide, in varying degrees of association with cell wall murein.