Analysis of CVC1302-Mediated Enhancement of Monocyte Recruitment in Inducing Immune Responses

Monocytes (Mos) are believed to play important roles during the generation of immune response. In our previous study, CVC1302, a complex of PRRs agonists, was demonstrated to recruit Mo into lymph nodes (LNs) in order to present antigen and secret chemokines (CXCL9 and CXCL10), which attracted antigen-specific CD4⁺ T cells. As it is known that Mos in mice are divided into two main Mo subsets (Ly6C⁺ Mo and Ly6C^- Mo), we aimed to clarify the CVC1302-recruiting Mo subset and functions in the establishment of immunity. In this study, we found that CVC1302 attracted both Ly6C⁺ Mo and Ly6C^- Mo into draining LNs, which infiltrated from different origins, injection muscles and high endothelial venule (HEV), respectively. We also found that the numbers of OVA⁺ Ly6C⁺ Mo in the draining LNs were significantly higher compared with OVA⁺ Ly6C^- Mo. However, the levels of CXCL9 and CXCL10 produced by Ly6C^- Mo were significantly higher than Ly6C⁺ Mo, which plays important roles in attracting antigen-specific CD4⁺ T cells. Under the analysis of their functions in initiating immune responses, we found that the ability of the Ly6C⁺ monocyte was mainly capturing and presenting antigens, otherwise; the ability of the Ly6C^- monocyte was mainly secreting CXCL9 and CXCL10, which attracted antigen-specific CD4⁺ T cells through CXCR3. These results will provide new insights into the development of new immunopotentiators and vaccines.