-gene assembly via somatic recombination

-~110 V gene segments

-~15 J gene segments

-less junction diversity

-somatic hypermutation

-development in bone marrow

-gene assembly via somatic recombination

-~120 V gene segments

-~74 J gene segments

-greater junction diversity

-no somatic hypermutation

-development in thymus

-first class of Ig to be produced after B cell activation

-secreted as a pentamer

-large size so in blood

-interacts with complement in C1

-activates classical complement pathway

-blood stream and extracellular spaces in tissues

-most studied/measured

-interacts with complement component C1

-activates classical complement pathway

-monomer

-dimer

-found in blood

-mucosal surface defense: gut, respiratory tract, milk

-defense against parasites

-allergic reactions such as asthma

-monomer

-mature naive B cells express ONLY IgM or IgD as membrane bound receptors

-activated B cells can switch class or isotype of Ig being produced

-happens outside of the bone marrow

-stimulated by antigen binding to BCR