Peritoneal macrophages of pathogen-free rats but not of conventional rats secrete elastolytic activity.

Elicited peritoneal macrophages from Sprague-Dawley rats conventionally bred and housed failed, as we have reported, to produce detectable elastolytic activity in culture. They did produce lysozyme and plasminogen activator. We now show that in contrast to these cells, macrophages from pathogen-free, barrier-sustained rats produced readily demonstrable elastolytic activity. Rats raised pathogen-free and subsequently housed conventionally for 2-4 wk appeared to lose the capacity to afford macrophages producing elastase. At the same time they acquired infections with several rat pathogens including Spironucleus muris, Kilham rat virus, sialodacryoadinitis virus, and mycoplasma pulmonis. The acquisition by the rats of one or more of these infections, conditions conducive to infection, or both factors may have suppressed their capacity to yield elastolytic activity.