Main author: Auður Anna Aradóttir Pind
Institution or Company: Department of Immunology, Landspitali, The National University Hospital of Iceland, Faculty of Medicine, School of Health Sciences, University of Iceland
Co-Authors, Institution or Company:
Ingileif Jónsdóttir, Department of Immunology, Landspitali, The National University Hospital of Iceland, Faculty of Medicine, School of Health Sciences, University of Iceland. Stefanía P. Bjarnarson, Department of Immunology, Landspitali, The National University Hospital of Iceland, Faculty of Medicine, School of Health Sciences, University of Iceland.
Introduction: The neonatal immune system is immature and antibody responses to either infection or vaccination are low and transient. One of the reason for transient antibody responses in early life is limited survival of plasma cells (PC) in bone marrow (BM), likely due to decreased survival factors. The aim of this study was to assess age-dependent maturation of accessory cells of the PC survival niche and their expression of the survival factors APRIL and IL-6.
Methods: Frequency and number of survival niche accessory cells; eosinophils, macrophages, megakaryocytes, monocytes, basophils, lymphocytes, dendritic cells and neutrophils in BM and their expression of plasma cell survival factors APRIL and IL-6 in 1, 2 and 3 weeks old mice was assessed by flow cytometry and compared to adult mice.
Results: The frequency and number of eosinophils, megakaryocytes, monocytes and neutrophils in BM was lower in 1-3 weeks old than adult mice. Lymphocyte frequency and numbers reached adult levels at 3 weeks and macrophages reached adult levels at 2 weeks. APRIL expression of BM cells was limited in young mice. In particular, APRIL+ eosinophils, macrophages, megakaryocytes, monocytes and lymphocytes had not yet reached adult levels in 3 weeks old mice. However, IL-6 expression was higher in 1-2 weeks old mice than adult mice where IL-6+ macrophages, monocytes, neutrophils and lymphocytes were enhanced.
Conclusion: Our study revealed limitations in APRIL expression by accessory cells in neonatal BM which likely contributes to limited survival of PC in early life leading to transient antibody responses in this age group.
