Erythrocyte Binding Properties of Streptococcal Lipoteichoic Acids

Abstract

The lipoteichoic acids (LTA) of gram-positive bacteria are known to bind spontaneously to a variety of animal cell membranes. We investigated the biological and biochemical characteristics of the binding of LTA of Streptococcus pyogenes and S. faecalis to human and sheep erythrocytes. The kinetics of the binding of the radiolabeled LTA ([ 3 H]LTA) from each of these organisms to erythrocytes was similar. The dissociation constants for sheep and adult human erythrocytes were 1.6 μM and 4.5 μM, respectively, whereas that of human cord blood erythrocytes was approximately 10-fold higher, 31 μM. The number of binding sites for sheep erythrocytes was calculated to be 7.2 × × 10 6 per cell, and that of human erythrocytes, 29 × 10 6 per cell. Binding was reversible. More than 50% of bound [ 3 H]LTA was displaced from erythrocytes by a 50-fold excess of unlabeled LTA. LTA prepared from heterologous species of gram-positive bacteria were all inhibitory to the binding of [ 3 H]LTA whether derived from S. pyogenes or from S. faecalis . Among a number of potential receptor analogues and other inhibitors tested, including serum albumin, gangliosides Gm 2 and Gm 3 , lipopolysaccharide of gram-negative bacteria, and various sugars, only albumin and the gangliosides significantly inhibited LTA binding. Trypsin or neuraminidase treatment of erythrocytes had no effect on LTA binding. Deacylation of [ 3 H]LTA abolished binding ability and binding was restored by esterification of the deacylated material with stearoyl chloride, indicating that ester-linked lipids are necessary for membrane binding.

Stimulation of monokine production by lipoteichoic acids

“…Removal of fatty acids entirely abolishes all stimulatory effects, and the deacylated products are unable to block the action of whole LTAs. LTAs have been reported to bind to, and in some cases influence the function of, several cell types, including epithelial cells (3,7,13), platelets (4), polymorphonuclear leucocytes (15), lymphocytes (5), and erythrocytes (6), and binding to granulocytes and monocytes apparently stimulates the respiratory burst (26,31). A requirement for fatty acids in mediating cell binding of LTA was previously shown (15,41).…”

Virulence of enterococci

“…Several biological characteristics of enterococcal lipoteichoic acids have been investigated. Beachey et al (13) noted that enterococcal lipoteichoic acid reversibly bound human erythrocytes as well as lipoteichoic acid from S. pyogenes. The acyl moiety of lipoteichoic acid was essential for binding (13).…”

“…Beachey et al (13) noted that enterococcal lipoteichoic acid reversibly bound human erythrocytes as well as lipoteichoic acid from S. pyogenes. The acyl moiety of lipoteichoic acid was essential for binding (13). Lipoteichoic acid is continually released from S. pyogenes independent of stage of growth cycle (2).…”

THE MITOGENIC PROPERTIES OF LIPOTEICHOIC ACID FROM STAPHYLOCOCCUS AUREUS

“…Beachey et al ( 6 ) found that removal of the lipid part from the LTA molecule abolished mitogenesis, and Hamada et al. (14) found that the mitogenic activity of dLTA from Streptococcus pyogenes was significantly lower than that of LTA.…”