B-cell receptor recognizing Streptococcus pneumoniae serotype 8 capsular polysaccharide (BCR-Spn8)

The B-cell receptor (BCR) recognizing Streptococcus pneumoniae serotype 8 capsular polysaccharide is a membrane-bound immunoglobulin complex found on the surface of B-lymphocytes that specifically identifies the Type 8 pneumococcal capsule. This receptor plays a pivotal role in the adaptive immune response against S. pneumoniae serotype 8, a pathogen frequently associated with invasive diseases such as pneumonia, bacteremia, and meningitis, particularly in adult populations. The capsular polysaccharide (CPS8) acts as a T-cell independent antigen that, upon binding, induces BCR clustering and cross-linking, thereby initiating a signaling cascade that drives B-cell activation and the production of protective antibodies. These antibodies are essential for the opsonization and subsequent phagocytic clearance of the bacteria. The signaling involves the recruitment of kinases such as Lyn and Syk, which activate downstream pathways like the PLC-gamma-2 and MAP kinase cascades. Therapeutic strategies, primarily in the form of polyvalent polysaccharide and conjugate vaccines, target these BCRs by presenting CPS8 epitopes to stimulate a robust and lasting humoral immune response. Modern conjugate vaccines, such as PCV20 and PCV21, enhance this response by coupling the polysaccharide to a carrier protein, thereby recruiting T-cell help and promoting the formation of high-affinity memory B cells. Monitoring the efficacy of these interventions often involves measuring serotype-specific IgG levels and opsonophagocytic activity in the serum.

Other names

Anti-Spn8 B-cell receptorSerotype 8-specific B-cell receptorB-cell receptor recognizing Streptococcus pneumoniae type 8 capsular polysaccharide epitopesPneumococcal serotype 8 B-cell receptor

Antigen-induced B-cell receptor cross-linking and activation