Immunity in humans (Introduction)

by David Turell , Friday, October 21, 2016, 18:20 (2955 days ago) @ David Turell

The human mechanism is amazing. The immune system cells build up a library of answers (antibodies) to all sorts of foreign attacks (infections)by altering their DNA as the person's life proceeds from childhood until death! Here is a newly found mechanism of detection:

https://www.sciencedaily.com/releases/2016/10/161020141101.htm

"Our cells regularly break down proteins from our own bodies and from foreign bodies, such as viruses and bacteria. Small fragments of these proteins, called epitopes, are displayed on the surface of the cells like little flags so that the immune system can scan them. If they are recognised as foreign, the immune system will destroy the cell to prevent the spread of infection.

"In a new study, researchers have discovered that around one third of all the epitopes displayed for scanning by the immune system are a type known as 'spliced' epitopes. These spliced epitopes were thought to be rare, but the scientists have now identified thousands of them by developing a new method that allowed them to map the surface of cells and identify a myriad of previously unknown epitopes.

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"Prior to the new study, scientists thought that the machinery in a cell created signalling peptides by cutting fragments out of proteins in sequence, and displaying these in order on the surface of the cell. However, this cell machinery can also create 'spliced' peptides by cutting two fragments from different positions in the protein and then sticking them together out of order, creating a new sequence.

"Scientists knew about the existence of the spliced epitopes, but they were thought to be rare. The new study suggests that spliced epitopes actually make up a large proportion of signalling epitopes: they make up around a quarter of the overall number of epitopes, and account for 30-40 per cent of the diversity -- the number of different kinds of epitopes.

"These extra epitopes give the immune system more to scan, and more possibilities of detecting disease. However, as the spliced epitopes are mixed sequences, they also have the potential to overlap with the sequences of healthy signallers and be misidentified as harmful."

Comment: The complexity of the immune system defies any explanation that proposes chance development.