title: Effects of surfactant protein-A on the interaction of Pneumocystis murina with its host at different stages of the infection in mice.
abstract: We examined the effects of surfactant protein A (SP-A), a collectin, on the interaction of Pneumocystis murina with its host at the beginning, early to middle, and late stages of infection. Pneumocystis murina from SP-A wild-type (WT) mice inoculated intractracheally into WT mice (WT(S)-WT(R)) adhered well to alveolar macrophages, whereas organisms from SP-A knockout (KO) mice inoculated into KO mice (KO(S)-KO(R)) did not. Substitution of WT mice as the source of organisms (WT(S)-KO(R)) or recipient host macrophages (KO(S)-WT(R)) restored adherence to that found with WT(S)-WT(R) mice. In contrast, when immunosuppressed KO and WT mice were inoculated with P. murina from a homologous source (KO(S)-KO(R), WT(S)-WT(R)) or heterologous source (WT(S)-KO(R), KO(S)-WT(R)) and followed sequentially, WT(S)-KO(R) mice had the highest levels of infection at weeks 3 and 4; these mice also had the highest levels of the chemokine macrophage inflammatory protein-2 and neutrophils in lavage fluid at week 3. Surfactant protein-A administered to immunosuppressed KO(S)-KO(R) mice with Pneumocystis pneumonia for 8 wk as a therapeutic agent failed to lower the organism burden. We conclude that SP-A can correct the host immune defect in the beginning of P. murina infection, but not in the middle or late stages of the infection.
authors.affiliation: Research Service, Department of Veterans Affairs Medical Center, Cincinnati, Ohio 45220, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Linke
authors.forename: Alan A
authors.initials: AA
authors.lastname: Ashbaugh
authors.forename: Judith V
authors.initials: JV
authors.lastname: Koch
authors.forename: Linda
authors.initials: L
authors.lastname: Levin
authors.forename: Reiko
authors.initials: R
authors.lastname: Tanaka
authors.forename: Peter D
authors.initials: PD
authors.lastname: Walzer