Vaccine For Pneumococcus Disease Possible, With New Immune System Finding

September 29, 2008

ScienceDaily (Sep. 27, 2008) — New research has shown how the immune system

detects and destroys the bug, pneumococcus, which could help in the

development of a new vaccine against the disease.

Pneumococcus is a bacterium which causes a lot of illness and disease in the

very young and the elderly, including pneumonia and meningitis. Large

numbers of pneumonia deaths occur in children every year especially in poor

countries. Existing vaccines are not ideal for use in such countries and are

also much too expensive.

Carriage of pneumococcus in the nose is a necessary first step for most

infections. As children age, they carry pneumococcus for shorter periods of

time and their risk of disease decreases also. The mechanisms underlying

this age-related decrease of carriage are not well understood.

As part of a continuing collaboration between labs at the universities of

Bristol and Harvard, researchers have shed new light on how the immune

system detects and destroys the bug when it colonises the nose. The study is

published in PLoS Pathogens.

American researchers led by Drs Malley and Marc Lipsitch have

produced evidence for a key role for the recently described cytokine

interleukin 17 in a mouse model of the infection. The Bristol group led by

Professor Adam Finn have shown that immune cells from children's tonsils,

removed at surgery, also produce IL17 when stimulated with pneumococci.

The researchers have identified the immune cells that are responsible for

this process, so-called TH17 cells, which release a factor that enables

human blood cells to kill pneumococcus more efficiently. They have shown

that these TH17 cells exist in adults and children, but not in newborn

babies, which suggests that they may arise as a consequence of humans being

exposed to pneumococcus.

Professor Finn said: " Understanding how children build up immunity to

pneumococcus will help the development of effective affordable vaccines for

use where they are most needed. "

In the past, immunity to pneumococcus was thought to be due entirely to

antibodies. This new research suggests that other mechanisms may be very

important too.

Adapted from materials provided by University of Bristol.

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