In: Biology
The current estimate is that mammalian b cells are capable of producing 1010 different immunoglobulins, each with a different hypervariable region. Explain the immunological consequence of this generation of diversity.
B cells secrete immunoglobulins (antibodies) which defend us against infections. In mammals, B cells produce five classes of antibodies which differ in their biological properties, functional locations and mediates a specific biological response following antigen binding. Hypervariable region (HVR, sites within the nuclear or mitochondrial DNA which have nucleotide repeats or substitutions) forms the antigen binding site, are found in both light and heavy chains and contributes to the specificity of each antibody.
Antibodies are proteins encoded by genes. Mammalian B cells are able to produce several different immunoglobulins due to the presence several genes in B cells. Moreover, the production of HVR of light and heavy antibody genes by DNA rearrangement also results in antibody diversity. Immunoglobulin light chains are encoded by V and J gene segments. Immunoglobulin heavy chains are also encoded by V and J gene segments, with additional diversity provided by D gene segment. Hence, the recombination of V, J, and D gene segments produce many variable domains.
Immunoglobulin diversity is achieved by following mechanisms:
Thus, combination of all these diversity mechanisms results in a vast repertoire of antibody specificity from limited number of genes which results in the several variations and possible combinations having vast diversity of unique antigen-binding sites. Hence, even with relatively small number of antibody genes successful recognition and eradication of different varieties of microbes is made possible.