Functional Enrichment and Analysis of Antigen Specific Memory B Cell Antibody Repertoires in PBMCs
Phenotypic screening of antigen specific antibodies in human blood is a common diagnostic test for infectious agents and a correlate of protection after vaccination. In addition to long lived antibody secreting plasma cells residing in the bone marrow, memory B cells are a latent source of antigen experienced, long term immunity that can be found at low frequencies in circulating PBMCs. Assessing the genotype, clonal frequency, quality, and function of antibodies resulting from an individual's persistent memory B cell repertoire can help inform the success or failure of immune protection. We have applied ELISPOT cell culture methods to functionally expand the memory repertoire from PBMCs and clonally map monoclonal antibodies from this population. We show that combining deep sequencing of stimulated memory B cell repertoires with retrieving single antigen specific cells is a promising approach in evaluating the latent, functional B cell memory in PBMCs.