Alveolar macrophage characteristics: effect of repeated lavages on cell activity

The effect of frequently repeated lavages on phenotypic and functional characteristics of alveolar macrophages (AM) from calves was studied. Following an interval of 48 h the proportion of AM expressing an Ia-like antigen increased from 10.3 +/- 1.9 to 21.3 +/- 3.2 (p less than 0.01). These cells exhibited a significant increase in antibody dependent cellular cytotoxicity (ADCC) (from 37.8 +/- 5.3% to 59.2 +/- 5.2%, p less than 0.01), whereas decreases in O2(-)-generation (from 28.0 +/- 1.8 to 19.7 +/- 1.1 nmol/5 X 10(5) cells/h) as well as in the intracellular rho-glucuronidase-content occurred. Small changes were also noted in ectoenzyme activities, PGE2- and interleukin 1-generation, whereas IgG-Fc-mediated phagocytosis was unaffected. By extending the lavage interval to six days, these dramatic changes were avoided, although a marginal effect was still seen on ADCC, binding of IgG- and C3b-sensitized particles as well as on ectoenzymes. After even longer intervals no effects were discernable. We conclude that it should be possible to perform repeated evaluations of AM phenotype and functional activities during immune and inflammatory processes in the same animal using a lavage-schedule of 6 days intervals, without adversely affecting the composition of the AM-population or cell activities.