[Immunological principles of polysaccharide-protein conjugate vaccination].
Haemophilus influenzae and Streptococcus pneumoniae are bacteria with a polysaccharide capsule. The production of specific antibodies against capsular polysaccharide plays a pivotal role in the defence against these organisms. However, children under the age of two years do not at all or only poorly respond to an infection with encapsulated bacteria or after vaccination with purified capsular polysaccharide antigen. In contrast, protein antigens, e.g. tetanus- and diphtheriae-toxoid, are good immunogens in this age group. The difference between polysaccharide antigen and protein antigen is that the former are T-dependent antigens whereas the latter are T-independent. The reason for this age dependent "immunodeficiency" is not clear. A functional immaturity of a B-cell population seems to be the reason for the unresponsiveness of young children against Ti-2 antigens. The Haemophilus conjugate vaccine contains the capsular polysaccharide chemically conjugated to a carrier protein. This results in an immune response against the polysaccharide with characteristics of a T dependent antigen, giving high immunogenicity even in children under the age of two years, resulting in high antibody-production and the induction of immunological memory.
Meyer
M
M
Universitäts-Kinderklinik Göttingen.
Gahr
M
M
D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D016667:Bacterial Capsules; D001428:Bacterial Vaccines / Q000276:immunology*; D002675:Child, Preschool; D000939:Epitopes / Q000276:immunology; D005260:Female; D018073:Haemophilus Vaccines / Q000276:immunology*; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D011247:Pregnancy; D013296:Streptococcus pneumoniae / Q000276:immunology*
D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D000939:Epitopes; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D011135:Polysaccharides, Bacterial