CD40LG and infection: Immunoglobulin mainly includes IgA, IgM, IgG, immunoglobulin E (IgE), and Immunoglobulin D (IgD), among which IgA is mainly divided into serotype and secretory immunoglobulin A (SIgA), which can reduce the adhesion rate of pathogenic bacteria, anti-inflammation, and anti-infection; IgG has the functions of antibacterial, antiviral, and immune regulation; IgE is related to allergy, and has a high affinity for basophils and mast cells [28,29].