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Engagement of FCRL5 enhances the development of human naïve B cells to plasmablasts

Friday, November 08, 2013 — Poster Session IV

2:00 p.m. – 4:00 p.m.

FAES Academic Center (Upper-Level Terrace)




  • HF Li
  • M Tolnay


Fc receptor-like 5 (FCRL5) is a B cell specific membrane protein that belongs to the FCRL family. FCRL5 has been shown to bind intact IgG, therefore an immune complex is expected to link FCRL5 to the B cell antigen receptor (BCR). FCRL5 has both ITAM and ITIM motifs in its cytoplasmic region. It has been shown that upon co-crosslinking of FCRL5 and BCR, SHP-1 phosphatase is recruited to the ITIM motif, and Lyn kinase to the ITAM motif. Therefore, FCRL5 potentially exerts binary influence on BCR signaling. Our lab has shown that FCRL5 expression is significantly induced upon BCR stimulation in human naïve B cells, but its biological function is elusive. In this study, FCRL5 was induced in human naïve B cells, and then stimulated together with BCR. We found that engagement of FCRL5 promoted B cell viability 5 days but not 3 days after BCR/FCRL5 co-stimulation. Three major B cell populations (CD19+/CD38high, CD19high/CD38+, CD19low/CD38low) emerged from the culture 5 days after BCR/FCRL5 co-stimulation. Compared to BCR stimulated cells, BCR/FCRL5 co-stimulated cells contained higher percentage of CD19+/CD38high (also CD27+) cells, defined as plasmablasts, and CD19high/CD38+ cells, while the percentage of CD19low/CD38low was decreased in FCRL5 engaged cell cultures.

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