title: CD45RO enriches for activated, highly mutated human germinal center B cells.
abstract: To date, there is no consensus regarding the influence of different CD45 isoforms during peripheral B-cell development. Examining correlations between surface CD45RO expression and various physiologic processes ongoing during the germinal center (GC) reaction, we hypothesized that GC B cells, like T cells, that up-regulate surface RO should progressively acquire phenotypes commonly associated with activated, differentiating lymphocytes. GC B cells (IgD(-)CD38(+)) were subdivided into 3 surface CD45RO fractions: RO(-), RO(+/-), and RO(+). We show here that the average number of mutations per IgV(H) transcript increased in direct correlation with surface RO levels. Conjunctional use of RO and CD69 further delineated low/moderately and highly mutated fractions. Activation-induced cytidine deaminase (AID) mRNA was slightly reduced among RO(+) GC B cells, suggesting that higher mutation averages are unlikely due to elevated somatic mutation activity. Instead, RO(+) GC B cells were negative for Annexin V, comprised mostly (93%) of CD77(-) centrocytes, and were enriched for CD69(+) cells. Collectively, RO(+) GC B cells occupy what seems to be a specialized niche comprised mostly of centrocytes that may be in transition between activation states. These findings are among the first to sort GC B cells into populations enriched for live mutated cells solely using a single extracellular marker.
authors.affiliation: Molecular Immunogenetics Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Jackson
authors.forename: Natessa
authors.initials: N
authors.lastname: Harp
authors.forename: Darshna
authors.initials: D
authors.lastname: Patel
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Zhang
authors.forename: Savannah
authors.initials: S
authors.lastname: Willson
authors.forename: Yoon J
authors.initials: YJ
authors.lastname: Kim
authors.forename: Christian
authors.initials: C
authors.lastname: Clanton
authors.forename: J Donald
authors.initials: JD
authors.lastname: Capra
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003564:Cytidine Deaminase / Q000276:immunology / Q000378:metabolism; D005260:Female; D018858:Germinal Center / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007072:Immunoglobulin D; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007223:Infant; D017493:Leukocyte Common Antigens; D008213:Lymphocyte Activation / Q000276:immunology*; D008297:Male; D012333:RNA, Messenger / Q000276:immunology / Q000378:metabolism; D027041:Somatic Hypermutation, Immunoglobulin / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D015854:Up-Regulation / Q000276:immunology; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
chemical_list: D015703:Antigens, CD; D007072:Immunoglobulin D; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D012333:RNA, Messenger; D017493:Leukocyte Common Antigens; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D003564:Cytidine Deaminase