Immune repertoire

The immune repertoire encompasses the different sub-types an organism's immune system makes of immunoglobulins or T-cell receptors. These help recognise pathogens in most vertebrates. The sub-types, all differing slightly from each other, can amount to tens of thousands, or millions in a given organism. Such a wide variety increases the odds of having a sub-type that recognises one of the many pathogens an organism may encounter. Too few sub-types and the pathogen can avoid the immune system, unchallenged, leading to disease.
Development.
Lymphocytes generate the immune repertoire by recombining the genes encoding immunoglobulins and T cell receptors through V(D)J recombination. Although there are only a few of these genes, all their possible combinations can result in a wide variety of immune repertoire proteins. Through selection, cells with autoreactive proteins (and thus may cause autoimmunity) are removed, while cells that may actually detect an invading organism are kept. The immune repertoire is affected by several factors:
Size.
Due to technical difficulties, measuring the immune repertoire was seldom attempted. Estimates depend on the precise type or 'compartment' of immune cells and the protein studied, but the expected billions of combinations may be an over-estimation. The genetic spatio-temporal rule governing the TCR locus rearrangements imply that V(D)J rearrangements are not random, hence resulting in a smaller V(D)J diversity.
Future developments.
Next generation sequencing may have a large impact. This can obtain thousands of DNA sequences, from different genes, quickly, at the same time, relatively cheaply. Thus it may be possible, to take a large sample of cells from someones immune system, and look quickly at the range of sub-types present in the sample. The ability to obtain data quickly from tens or hundreds of thousands of cells, one cell at a time, should provide a good idea, of the size of the person's immune repertoire. These large-scale adaptive immune receptor repertoire sequencing (AIRR-seq) data require specialized bioinformatics pipelines to be analyzed effectively. Many computational tools are being developed for this purpose. The Immcantation framework provide a start-to-finish analytical ecosystem for high-throughput AIRR-seq data analysis. The AIRR Community is community-driven organization that is organizing and coordinating stakeholders in the use of next-generation sequencing technologies to study immune repertoires. In 2017, the AIRR Community published recommendations for a minimal set of metadata that should be used to describe an AIRR-seq data set when published and deposited in a public repository. 