Fully human monoclonal antibodies from antibody secreting cells after vaccination with Pneumovax®23 are serotype specific and facilitate opsonophagocytosis

Abstract

B lymphocyte memory generates antibody-secreting cells (ASCs) that represent a source of protective antibodies that may be exploited for therapeutics. Here we vaccinated four donors with Pneumovax23 and produced human monoclonal antibodies (hmAbs) from ASCs. We have cloned 137 hmAbs and the specificities of these antibodies encompass 19 of the 23 serotypes in the vaccine, as well as cell wall polysaccharide (CWPS). Although the majority of the antibodies are serotype specific, 12% cross-react with two serotypes. The Pneumovax23 ASC antibody sequences are highly mutated and clonal, indicating an anamnestic response, even though this was a primary vaccination. Hmabs from 64% of the clonal families facilitate opsonophagocytosis. Although 9% of the total antibodies bind to CWPS impurity in the vaccine, none of these clonal families showed opsonophagocytic activity. Overall, these studies have allowed us to address unanswered questions in the field of human immune responses to polysaccharide vaccines, including the cross-reactivity of individual antibodies between serotypes and the percentage of antibodies that are protective after vaccination with Pneumovax23.

Large-scale sequence and structural comparisons of human naive and antigen-experienced antibody repertoires

“…We observed signatures of convergent light-chain genes among public antibodies expressing the same CDR-H3 amino acid sequence (SI Appendix, Fig. S6B), contributing additional evidence to the hypothesis that public antibodies can be elicited in response to common immune stimuli (SI Appendix, Table S3) (40,(42)(43)(44)(45)54).…”

“…S6B), reinforcing the hypothesis that public antigen-experienced CDR-H3 antibodies can be functionally selected for binding to common antigens (42)(43)(44)(45).…”

“…Public VH sequences have been reported to arise in individuals infected with certain pathogens and also at a low frequency in healthy donors (10,40,(42)(43)(44)54). However, the question of whether the light chains paired with public heavy chains are also shared among individuals had not been addressed.…”

Structures of Preferred Human IgV Genes–Based Protective Antibodies Identify How Conserved Residues Contact Diverse Antigens and Assign Source of Specificity to CDR3 Loop Variation

“…and their clearance by complement-dependent phagocytosis (17). Vaccination with PPS or protein-conjugated PPS containing up to 23 different serotypes is recommended for small children, the elderly, and other susceptible populations.…”

“…We also present the structure of the L-rhamnose complex of the Fab fragment of another anti-23F Ab, pn132p2C05 (C05). Using methodology described by Smith et al (17), this authentic human Ab with naturally paired H and L chains was isolated after vaccination with Pneumovax 23 from a donor different from the one providing 023.102. Finally, as a second representative of an anti-HCMV Ab, we show the crystal structure of the AD-2S1 Ag complex of the KE5 Fab, an Ab that also utilizes IGKV3-11 and IGHV3-30 genes but IGHD and IGKJ genes different from those used by a previously crystallized anti-HCMV Fab, 8F9 (24).…”