B-cell receptor specific for pneumococcal capsular polysaccharide (BCR-PPS)

B-cell receptors (BCRs) specific for pneumococcal capsular polysaccharide (PPS) epitopes are membrane-bound immunoglobulins that recognize the complex carbohydrate structures of the Streptococcus pneumoniae capsule (Source: PubMed, PMID: 22461495). These receptors are critical for the adaptive immune response, as they mediate the recognition of T-cell independent type 2 (TI-2) antigens, leading to B-cell activation and the production of serotype-specific antibodies (Source: NIH, StatPearls - Pneumococcal Vaccine). The interaction between the BCR and PPS epitopes is the fundamental mechanism by which pneumococcal vaccines, such as the 23-valent polysaccharide vaccine (PPSV23) and various conjugate vaccines (PCV13, PCV20), induce protective immunity (Source: CDC - Pneumococcal Disease). Binding of the vaccine antigen to the BCR triggers intracellular signaling pathways that result in the generation of plasma cells and, in the case of conjugate vaccines, memory B cells through T-cell recruitment (Source: Nature Reviews Immunology, doi:10.1038/nri3444). These receptors are primary targets for preventing invasive diseases like pneumonia, meningitis, and sepsis, particularly in vulnerable populations such as children and the elderly (Source: WHO - Pneumococcal vaccines). The specificity of these BCRs is determined by the unique chemical structure of the polysaccharide capsule, which varies across over 100 known serotypes of the pathogen. Effective engagement of these receptors is necessary to produce opsonizing antibodies that facilitate the clearance of the bacteria by phagocytes. Therapeutic challenges include the poor immunogenicity of pure polysaccharides in infants, which is overcome by conjugating the polysaccharides to carrier proteins to engage T-cell help.

Other names

Anti-PPS B-cell receptorPneumococcal polysaccharide-specific BCRPPS-specific B-cell receptorStreptococcus pneumoniae capsular polysaccharide-specific BCR

Antigen binding to the B-cell receptor triggers receptor clustering and intracellular signaling, leading to B-cell proliferation and differentiation into antibody-secreting plasma cells.