B cell specific to Streptococcus pneumoniae type 9V capsular polysaccharide antigen (null)

B cells specific to Streptococcus pneumoniae type 9V capsular polysaccharide antigen are a functional subset of B lymphocytes that recognize repeating carbohydrate structures (polysaccharides) forming the outer capsule of pneumococcal serotype 9V. Their activation leads to antibody-mediated immunity, which is critical for protection against invasive pneumococcal disease. The response is typically T-independent, mobilizing marginal zone and switched B cells, and is enhanced if the polysaccharide antigen is conjugated to a protein carrier. These B cells’ activity is essential for the efficacy of polysaccharide and conjugate vaccines, but their response can be suboptimal in specific populations (e.g., young children, immunocompromised patients). Measurement of antigen-specific IgG and phenotyping of B cell subsets are used as biomarkers for vaccine response. Safety concerns include the poor vaccine efficacy in infants with unconjugated antigens and variable immunogenicity depending on antigen stability and host immune status[1][2][3][5][6].

Other names

B cell targeting pneumococcal type 9V capsular polysaccharide9V-specific B cellanti-9V polysaccharide B cellmarginal zone B cell responding to 9V polysaccharide

Active immunization triggers these B cells to undergo clonal expansion and differentiation into plasma cells that secrete specific antibodies (IgG, IgM) against the 9V polysaccharide T-independent (TI) activation for polysaccharide antigens, especially mobilizes marginal zone B cells in humans Isotype switching (from IgM to IgG) requires conjugation to a protein carrier (e.g., tetanus toxoid)