Changes in the composition of canine respiratory cells obtained by bronchial lavage following irradiation or drug immunosuppression

Canine respiratory cells, obtained by bronchial lavage, and blood leukocytes were monitored to observe cellular changes following acute and chronic immunosuppression. Irradiation (350 R) produced bone marrow suppression and prompt peripheral blood leukopenia, but did not affect recovery of pulmonary alveolar macrophages or lymphocytes for 12 days after. Treatment for 6 weeks with daily methylprednisolone (1 mg/kg) caused a progressive decrease in the number of recoverable respiratory lymphocytes, whereas alternate day methylprednisolone (2 mg/kg) had less effect. Cyclophosphamide in combination with steroids generally augmented the progressive loss of blood and respiratory lymphocytes. Recovery of alveolar macrophages was not changed appreciably. Thus, the population of lung macrophages, sampled by pulmonary lavage, withstood acute and chronic forms of immunosuppression very well. In contrast, canine lymphocytes seem more susceptible to injury, especially to drug regimens containing steroids