The six immune function tests usually include immunoglobulin A, immunoglobulin G, immunoglobulin M, complement C3, complement C4, rheumatoid factor, and C-reactive protein. If the values test abnormal, autoimmune diseases such as congenital immunodeficiency disease, systemic lupus erythematosus, rheumatoid arthritis, and chronic liver disease can be detected. Because normal immunoglobulin and complement values usually indicate normal immunity, the presence of abnormalities can determine the presence of abnormal immune responses in the body. Immunoglobulin G is the most abundant and major immunoglobulin in the body, accounting for 70%-80% of the total immunoglobulins. It is a re-immune response antibody and has antibody activity against viruses, bacteria and parasites. If immunoglobulin G, immunoglobulin A, and immunoglobulin M are elevated, and complement C3 and complement C4 are decreased, it means that B cells and plasma cells in the patient’s body are proliferating abnormally and producing large amounts of immunoglobulins, suggesting that the patient may have an autoimmune disease. This is because when a patient suffers from an autoimmune disorder, abnormal immune response occurs in the body with abnormal inter-antigen-antibody reactions to complement C3 and complement C4, and this immune response depletes the complement in the body, with a subsequent decrease in complement. In addition, if elevated C-reactive protein or rheumatoid factor is detected at the same time, it indicates a greater likelihood of autoimmune disease. If immunoglobulin G, immunoglobulin A, and immunoglobulin M are significantly lower in the immune panel 6, it suggests that immunodeficiency diseases such as congenital immunodeficiency disease, heavy chain disease, light chain disease, nephrotic syndrome, and infections may also be present. Immunoglobulin A and immunoglobulin M may also be significantly decreased in patients after immunosuppressive treatment, such as glucocorticoid or immunosuppressive therapy.