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.
Department of Immunology, University Hospital for Children and Youth, Wilhelmina's Children Hospital, Utrecht, The Netherlands. grijkers@wkz.azu.nl
G T
GT
Rijkers
E A
EA
Sanders
M A
MA
Breukels
B J
BJ
Zegers
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