Lipoteichoic acid fractions from pathogenic and apathogenic Listeria species and Staphylococcus aureus induce similar amounts of macrophage-derived cytokines.

Lipoteichoic acids (LTAs) of pathogenic and apathogenic Listeria species and of Staphylococcus aureus were fractionated and tested for their ability to stimulate production of cytokines (IL-1alpha, IL-6, TNF-alpha) in resident peritoneal macrophages (Mvarphi) of endotoxin-resistant C3H/HeJ mice using a serum-free medium. For IL-1alpha and IL-6 there were no detectable differences in the ability of LTA fractions of pathogenic and apathogenic Listeria species and of Staphylococcus aureus. However, LTA-2 fractions of Staphylococcus aureus, which might be less hydrophobic than the LTA-2 fractions of the listeriae-induced lower amounts of TNF-alpha. Furthermore, the more lipophilic LTA-2 fractions of all LTAs employed were more potent inducers of cytokines than the less lipophilic LTA-1 fractions. The biologic effect of LTAs appears, therefore, to depend mainly on their hydrophobicity.

Cell-surface location of Listeria-specific protein p60--detection of Listeria cells by indirect immunofluorescence.

A specific polyclonal antiserum was prepared against a gel-purified 60 kDa extracellular protein of Listeria monocytogenes ATCC 19111 corresponding to protein p60 previously detected in culture broths of L. monocytogenes strains Mackaness and EGD [Kuhn, M. & Goebel, W. (1989), Infection and Immunity 57, 55-61]. Indirect immunogold labelling combined with transmission electron microscopy and high-resolution scanning electron microscopy were used to investigate the location and distribution of p60 on the bacterial cell surface. In bacteria grown to the early stationary phase about 25% of the extracellular protein was estimated to be associated with the cell surface. The anti-p60 antiserum proved to be Listeria-specific. In an indirect immunofluorescence test the antiserum reacted with Listeria strains representing all species and different serotypes, except L. seeligeri, L. welshimeri, L. grayi and L. murrayi. No immunological cross-reactions were observed with 27 strains of bacteria from 16 other genera. The value of the anti-p60 antiserum in developing a diagnostic assay for Listeria cells in environmental samples and foods is discussed.

Occurrence and structure of lipoteichoic acids in the genus Staphylococcus.

Lipoteichoic acids were isolated from eleven species of the genus Staphylococcus using phenol-water partition and hydrophobic chromatography on octyl-Sepharose CL-4B. The lipoteichoic acids purified could be visualized by SDS-PAGE. They were shown to be composed of a hydrophilic poly(glycerophosphate) chain covalently linked to gentiobiosyldiacylglycerol, the common lipid anchor of these molecules. Glycerophosphate units of the hydrophilic chain were found to be partly substituted with ester-linked D-alanine, except in the case of S. cohnii. The lipoteichoic acids isolated from S. cohnii, S. hominis, S. saprophyticus and S. simulans contain alpha(1-2)-linked N-acetylglucosamine as an additional substituent of the poly(glycerophosphate) backbone.