This document discusses the role that antibody constant regions play in binding to pneumococcal polysaccharides. It summarizes that the constant region determines the antibody isotype, which can influence avidity and fine specificity. The author aims to express identical variable regions from human antibodies targeting pneumococcal polysaccharides with either IgG1 or IgG2 constant regions. Surface plasmon resonance will then be used to compare binding of the two isotypes to determine if constant region impacts affinity. Understanding this relationship could help design vaccines that direct the immune response towards the optimal isotype.