Positive antibodies indicate the presence of an immune response against an antigenic component in the body. Antibodies are essentially immunoglobulins, a type of globulin produced by the body’s immune system in response to antigenic stimulation, when B-cells proliferate and differentiate into plasma cells, which can bind specifically to the corresponding antigen. There is a wide variety of antibodies that can be detected clinically, due to the presence of a corresponding diversity of antigenic components, against which an immune response can be generated, resulting in a positive antibody in the serum. Positive antibodies can be detected when the body is infected with pathogenic microorganisms such as viruses and bacteria. IgM is the earliest antibody to appear in the initial humoral immune response, and the detection of IgM in the serum suggests that the infection is recent and can be used for the early diagnosis of the infection, while a positive IgG antibody suggests that the infection is a previous one. Autoantibodies may be positive if the body has an immune response against its own antigenic components, such as antinuclear antibodies and rheumatoid factor.