There are several types of immunoglobulins.

Immunoglobulins are antibody molecules produced by antibody-generating cells and are a crucial component of the human immune system. There are five types of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, each serving distinct functions. IgA is the most common type of immunoglobulin and is primarily distributed in mucosal surfaces of the digestive tract, respiratory tract, and urinary tract, where it blocks the invasion of external pathogens and reduces inflammatory responses. IgD is mainly found on the surface of B cells and plays a key role in regulating immune responses. IgE is primarily located in the lungs, skin, and intestines. It can recognize specific antigens and transmit these antigen-recognition signals to eosinophils, thereby triggering an immune response. IgG is the most abundant immunoglobulin after IgA and primarily functions as an antigen-binding antibody, antimicrobial antibody, antitoxin antibody, and precipitation antibody. IgM is mainly present in serum and lymphatic fluid and is the first antibody released by the body in response to viral infections and foreign antigen invasion, providing effective early-stage protection.