soumadoc
Forum Newbie
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what s the allelic exclusion and how can somatic mutation in variable Ig chains increase their affinity?
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| simi
Forum Elite
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even i have some confusion about allelic exclusion....immunology is my weakest area...and i am doing my first read of immunology.
according to kaplan...the cell produces functional heavy and light chains by rearranging the gene segments of homologous chromosomes.Once functional product has been achieved by one of these rearrangements,the cell shuts off the rearrangement and expression of other allele on the homologous chromosome- a process known as ALLELIC EXCLUSION.This process ensures that B and T lymphocytes synthesize only one specific antigen -receptor per cell.
when the cell shuts off the rearrangement and expression of other allele ...how can it be allelic exclusion?? since it is homologous chromosome the alleles r identical isn't it?
According to other source....In HETEROZYGOUS individuals who have ,for example, inherited two alternative forms of the constant region gene for IgG1(i.e...IgG1m(1) and IgG1m(2), both forms will be found in the individuals total complement of Igs, but any one given B cell will express only Igs of one allotype.This phenomenon is known as allelic exclusion, and it indicates that only one of two parental chromosomes express that gene in any given B cell.
Please any one throw some light on it......i think allelic exclusion occurs in heterozygous individuals...any guidance would be highly appreciated.
Somatic hypermutation generates antibody diversity....this mechanism operates to introduce point mutations at a very high rate into the V regions of heavy and ligt chains.Some of the mutations produce antibody molecules that are a better fit for antigen than the original antibody.These new antibodies tend to bind antigen witha higher affinity and B cells expressing them are preferentially selected for maturation into plasma cells.
Please correct me if i am wrong.
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