Infant B cell responses to polysaccharide determinants.
Newborns and infants up to the age of 1.5-2 years of age are unable to produce antibodies to bacterial capsular polysaccharides. As a consequence, children up to the age of 2 years have an increased susceptibility for infections with encapsulated bacteria. Capsular polysaccharides are classified as so-called T cell independent type 2 antigens and induce IgG2 antibodies. The mechanism of B lymphocyte activation by polysaccharides differs from that of protein antigens and involves co-stimulation by CD21 (type 2 complement receptor). Reduced expression of CD21 on neonatal B lymphocytes can explain unresponsiveness to polysaccharides. Polysaccharide protein conjugates have the ability to overcome unresponsiveness to polysaccharides early in life. The response induced is predominant IgGl.
Rijkers
G T
GT
Department of Immunology, University Hospital for Children and Youth, Wilhelmina's Children Hospital, Utrecht, The Netherlands. grijkers@wkz.azu.nl
Sanders
E A
EA
Breukels
M A
MA
Zegers
B J
BJ
D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D002675:Child, Preschool; D000939:Epitopes / Q000276:immunology* / Q000494:pharmacology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000276:immunology* / Q000494:pharmacology
D000939:Epitopes; D011135:Polysaccharides, Bacterial