In particular, low-status individuals showed high levels of activity in genes associated with the production of various immune-related cells and chemical signalling factors, as well as those to do with inflammation (a general immune response that involves tissue swelling and increased immune-cell activity in the affected area).

ECONOMIST: Social status and health

In those with a milder form of the disease, they found a protein associated with a bacterial immune response - interferon-gamma.

BBC: 'Wrong' immune response aids TB

It is thought that several cancer types are associated with infections, and a weakened immune system - such as that found in a HIV patient - is less able to mop these up.

BBC: HIV patients at risk of cancer