Page 203 - Veterinary Immunology, 10th Edition

of the complement fragment, C5a. The cytokines and C5a in turn
VetBooks.ir trigger the activation of more T cells and the release of more

cytokines, leading to even greater cell destruction. This “cytokine
storm” can cause severe illness or death. The most important of

these cytokine storms results from massive tissue trauma or burns.
However, many viruses such as influenza and dengue, can also
trigger cell destruction, leading to excessive cytokine release and
death. (Box 7.2).

Box 7.2

Immune Reconstitution Inflammatory

Syndrome!

When bats hibernate their body temperature drops and they may

become immunosuppressed. This permits the causal agent of white
nose syndrome, a filamentous fungus called Pseudogymnoascus
destructans, to colonize and erode the skin of their wings, ears, and
muzzle. About a week after infected bats emerge from hibernation,

they develop an intense inflammatory response that leads to their
death. It has been suggested that the sudden reversal of immune
suppression that occurs when their body temperature rises results
in the development of immune reconstitution inflammatory

syndrome (IRIS). This syndrome was first reported in humans
following the abrupt reversal of immunosuppression. (For
example, in AIDS patients following the onset of effective
antiretroviral therapy.) It is believed that the recovery of T cell

function drives an exaggerated immune response against the
underlying infection that results in significant tissue damage. Thus
in white nose syndrome, cold-loving P. destructans is present in
infected tissues. When body temperature returns to normal, T cell

function is rapidly restored, leading to a massive neutrophil influx
and resulting in tissue destruction.

Meteyer CU, Barber D, and Mandl JN. Pathology in euthermic bats with white nose
syndrome suggests a natural manifestation of immune reconstitution inflammatory
syndrome. Virulence 3:10-16, 2016.

Bacterial Septic Shock

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