Enhanced IgG1‐mediated antibody response towards thymus‐dependent immunization in CXCR1‐deficient mice

• Main Authors: Jennifer Jaufmann, Melanie Carevic, Leyla Tümen, Derya Eliacik, Fee Schmitt, Dominik Hartl, Sandra Beer‐Hammer
• Format: Article
• Language: English
• Published: Wiley 2021-03-01
• Series: Immunity, Inflammation and Disease
• Subjects: B‐1 cells; B‐2 cells; chemokine receptors; CXCR1; germinal center reaction; innate and adaptive antibody responses
• Online Access: https://doi.org/10.1002/iid3.380

Abstract Background Chemokine receptors and their corresponding ligands are key players of immunity by regulation of immune cell differentiation and migration. CXCR1 is a high‐affinity receptor for CXCL8. Differential expression of CXCR1 is associated with a variety of human pathologies including cancer and inflammatory diseases. While various studies have highlighted the importance of CXCR1‐mediated CXCL8‐sensing for neutrophil trafficking and function, its role in B‐cell responses remains unsolved. Therefore, our aim was to investigate innate and adaptive antibody responses in CXCR1‐deficient mice. Methods Cell populations of the spleen and the peritoneal cavity were identified and quantified via flow cytometry. To investigate thymus‐independent (TI) and thymus‐dependent (TD) antibody responses, mice were immunized intraperitoneally with TNP‐Ficoll, Pneumovax23, and TNP‐Chicken Gamma Globulin. Mice were bled before as well as 7 and 14 days after vaccination to collect serum. Serum antibody levels overtime were analyzed according to their specificity by enzyme‐linked immunosorbent assay. B‐1 cell functionality was examined by IL‐5/IL‐5Rα‐dependent stimulation of peritoneal and splenic cells in vitro. To analyze CXCR1/2‐expression, CD19+ splenocytes were enriched by magnetic‐activated cell sorting before isolation of total RNA contents, followed by reverse transcription and real‐time polymerase chain reaction. Results The distribution of natural B‐1 cell populations was disturbed in the absence of CXCR1, while their responsiveness towards TI antigens and in vitro stimulation remained functional. Besides, CXCR1‐deficiency was accompanied by increased frequencies of follicular B‐2 cells in the spleen. Interestingly, these mice produced elevated levels of antigen‐specific IgG1 upon TD immunization and harbored a significantly enlarged proportion of CXCR5‐expressing T helper (H) cells. CXCR1‐expression was detectable in CD19+ splenocytes derived from wild‐type, but not CXCR1‐deficient mice. Conclusion Our data demonstrate a previously unknown relevance of CXCR1 for the production of specific IgG1 in response to vaccination. These findings identify CXCR1 as a promising candidate for future studies on the regulation of adaptive antibody responses.