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.
IgE is one of the five isotypes of human immunoglobulins and plays role in helminthic infestations and allergic reactions.
Based on the location of antigenic determinants sites, immunoglobulins are divided into, isotypes, allotypes, and idiotypes.
IgA is the second most abundant class of immunoglobulin. sIgA is a dimer and is confers mucosal immunity.
Antibodies are Y-shaped tetra-peptide molecules consisting 2H and 2 L chains. There are 5 classes of immunoglobulins IgG, IgA, IgM, IgE, and IgD.
These are antibodies derived from a single clone of a plasma cell. Monoclonal antibodies are used in the treatment of various diseases and cancers.
Neutralization of pathogens, phagocytosis, mucosal immunity, ADCC and complement mediated lysis are major functions of antibodies.
IgG antibody crosses the placenta and plays an important role in protecting the developing fetus. IgG is the most abundant Ig in serum.