VMC 221: Veterinary Immunology and Serology (1+1)

HEAVY CHAINS

• In general there are five types of Ig heavy chain denoted by the Greek letters: α, δ, ε, γ, and μ , which determines the class of antibody such as IgA, IgD, IgE, IgG, and IgM antibodies respectively.
• Distinct heavy chains differ in size and composition, α and γ contain approximately 450 amino acids, while μ and ε have approximately 550 amino acids.
• Each heavy chain has two regions, the constant region and the variable region .
• The constant region is identical in all antibodies of the same isotype, but differs in antibodies of different isotypes.
• Heavy chains γ, α and δ have a constant region composed of three domains, and a hinge region. Heavy chains μ and ε have a constant region composed of four domains.
• The variable region of the heavy chain differs in antibodies produced by different B cells, but they are same for all antibodies produced by a single B cell or B cell clone.
• The variable region of each heavy chain is approximately 110 amino acids long and is composed of a single Ig domain .