Correlation of organism burden and alveolar macrophage counts during infection with Pneumocystis carinii and recovery.
Changes in the number of alveolar macrophages were correlated with organism burden during Pneumocystis carinii infection. The lungs of healthy, dexamethasone-treated, and dexamethasone-treated and P. carinii-infected rats were lavaged with phosphate-buffered saline. Counting of alveolar macrophages in the lavage fluids revealed that P. carinii infection caused a 58% decrease in the number of alveolar macrophages and that higher P. carinii organism burdens caused a more rapid decrease in alveolar macrophage number. As a control, healthy rats were challenged with the same number of organisms as that normally used to generate P. carinii infections in dexamethasone-treated rats. Thirteen days after challenge, these rats had a profound (54%) increase in alveolar macrophage number in response to the challenge, while the number of alveolar macrophages in immunosuppressed and P. carinii-infected rats had decreased significantly by this time point. These experiments created the first animal model to mimic human pneumocystis pneumonia in alveolar macrophage number alterations. Reduction of P. carinii organism numbers by treatment of rats with trimethoprim and sulfamethoxazole brought a slow rebound in alveolar macrophage number, while recovery from P. carinii infection by cessation of immunosuppression brought a rapid rebound in alveolar macrophage number. These results suggest that both the immune state of the host and P. carinii burden affect alveolar macrophage number.
Lasbury
Mark E
ME
Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA. melasbur@iupui.edu
Durant
Pamela J
PJ
Bartlett
Marilyn S
MS
Smith
James W
JW
Lee
Chao-Hung
CH
D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D002452:Cell Count; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology; D008168:Lung / Q000276:immunology; D016676:Macrophages, Alveolar / Q000166:cytology / Q000276:immunology* / Q000382:microbiology; D011010:Pneumocystis / Q000254:growth & development*; D011020:Pneumonia, Pneumocystis / Q000188:drug therapy / Q000276:immunology* / Q000382:microbiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology
D000890:Anti-Infective Agents; D005938:Glucocorticoids; D003907:Dexamethasone; D015662:Trimethoprim, Sulfamethoxazole Drug Combination