Is Pneumocystis a Cause of Asthma?

In a mouse model, Pneumocystis infection is associated with an allergic-type reaction in the lung; humans with severe asthma have elevated antibody levels to Pneumocystis antigen.

Pneumocystis is a fungus with a limited host range whose human species, P. jirovecii, is a cause of pneumonia in highly immunosuppressed patients, particularly those with HIV-1 infection and very low CD4+ lymphocyte counts. Considerable evidence indicates that humans are exposed to Pneumocystis at a very early age and then throughout life through airborne spread.

Hypothesizing that Pneumocystis could be a cause of asthma, investigators at the University of Pittsburgh exposed mice to P. murina, the murine species of the fungus. They noted an increase in expression of type II allergic cytokines, such as interleukin (IL)-4 and IL-5, in lung tissue. Depletion of CD4+ lymphocytes blocked these responses.

Subsequently, in human patients, the resear…

Reviewing Author

Neil M. Ampel, MD

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Editorial BoardsUpToDate

Leadership Positions in Professional SocietiesCoccidioidomycosis Study Group (Past President, Secretary, Treasurer)

Neil M. Ampel, MD

Disclosures

Editorial BoardsUpToDate

Leadership Positions in Professional SocietiesCoccidioidomycosis Study Group (Past President, Secretary, Treasurer)

Is Pneumocystis a Cause of Asthma?

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Reviewing Author