Decreased serum and pharyngeal antibody levels specific to streptococcal lipoteichoic acid in children with recurrent tonsillitis.

OBJECTIVE: Streptococcus (S.) pyogenes is a common cause of primary as well as recurrent tonsillitis (RT). Lipoteichoic acid (LTA) has been proposed as a possible candidate for vaccine formulation against streptococcal infections, because LTA is a common constituent of streptococci and the antibody to LTA inhibits bacterial attachment to epithelial cells in vitro. Streptolysin-O and streptococcal whole cell body are highly immunogenic and the antibodies to these antigens are reported to be better parameters for streptococcal infections The objective of the present study is to investigate how systemic and local immune activities against S. pyogenes may be associated with RT.
METHODS: Sera from 178 children with or without RT aged 1-15 years with a median age of 5 years were investigated for the levels of total immunoglobulins and antibodies specific to streptococcal antigens such as whole cell body, LTA, and streptolysin-O. Pharyngeal secretions from 67 children with or without RT aged 2-14 years with a median age of 6 years were subjects to secretory IgA (SIgA) antibody levels to streptococcal LTA. The antibodies to whole cell body and LTA were measured by enzyme-linked immunosorbent assay. Total immunoglobins and the anti-streptolysin-O antibody were assayed by nephelometry.
RESULTS: An age-matched comparison revealed that either levels of serum IgG antibody or pharyngeal SIgA antibody to streptococcal LTA at 2-5 years of age were significantly lower in RT children than in non-RT children (1.39 vs. 5.14 microg/ml, P=0.001; 10.6 vs. 29.9 units/ng/ml total SIgA, P=0.015; respectively) and correlated inversely to episodes of tonsillitis (r=-0.242, P=0.024; r=-0.3, P=0.024; respectively). Either serum total immunoglobulin levels of IgG or IgA correlated positively to episodes of tonsillitis in children aged 2-5 years (r=0.293, P=0.011; r=0.361, P=0.002; respectively). No difference was found on either serum levels of IgG antibody to streptococcal whole cell body or antibody to streptolysin-O between RT and non-RT children in any age-matched comparisons. High serum antibody levels to whole cell body was associated with high antibody levels to streptococcal LTA in non-RT children (r=0.198, P<0.05), but no association was found between these antibody levels in RT children.
CONCLUSIONS: Selective immunologic failure in systemic and pharyngeal antibody response to streptococcal LTA may be a potential cause of RT in young children.