There are five classes of antibodies based on the amino acid sequences present in the heavy chain of an immunoglobulin, these are IgG, IgA, IgM, IgD, IgE. Due to the presence of different light chain types, kappa and lambda, each antibody class can also exist at two types.
IgG and IgA are further divided into subclasses based on minor differences in amino acid sequences in the constant regions of heavy chains. There are four subclasses of IgG: IgG1, IgG2, IgG3, and IgG4, and two subclasses of IgA, IgA1, and IgA2.
