Inhaled platelet-activating factor causes pulmonary neutrophil sequestration in normal humans.
Inhaled platelet-activating factor (PAF) causes bronchoconstriction and transient peripheral neutropenia in humans. We studied eight normal subjects to investigate whether inhaled PAF caused pulmonary neutrophil sequestration. All subjects received autologous 99mTc-red cells as a blood pool marker, seven received 111In-neutrophils, and one received 111In-platelets. Six subjects inhaled 48 micrograms of PAF. There was immediate pulmonary sequestration of 111In-neutrophils, maximal (218% baseline) at 6 min (p less than 0.001), returning to normal by 3 h. There was no change in circulating platelet count or pulmonary 111In-platelet transit. Methacholine inhalation caused equivalent bronchoconstriction to PAF, but it had no effect on neutrophil count or pulmonary 111In-neutrophil activity. We have demonstrated pulmonary neutrophil, but not platelet, sequestration after PAF. This supports a role for PAF as an inflammatory mediator in humans. This may be a useful model for exploring pulmonary neutrophil kinetics and preinflammatory processes.
Tam
F W
FW
Department of Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, United Kingdom.
Clague
J
J
Dixon
C M
CM
Stuttle
A W
AW
Henderson
B L
BL
Peters
A M
AM
Lavender
J P
JP
Ind
P W
PW
D000280:Administration, Inhalation; D000328:Adult; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology; D001985:Bronchial Provocation Tests; D004912:Erythrocytes; D006801:Humans; D007205:Indium Radioisotopes; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D009942:Organometallic Compounds; D010972:Platelet Activating Factor / Q000008:administration & dosage / Q000494:pharmacology*; D010976:Platelet Count; D011877:Radionuclide Imaging; D013667:Technetium; D013997:Time Factors; D014334:Tropolone / Q000031:analogs & derivatives
D007205:Indium Radioisotopes; D009942:Organometallic Compounds; D010972:Platelet Activating Factor; C043895:indium tris(tropolonate); D013667:Technetium; D014334:Tropolone