Effect of Micropolyspora faeni cells and cell wall fractions on rabbit alveolar macrophages.

The reactivity of alveolar macrophages (AM) to cells and cell wall fractions (CWF) of Micropolyspora faeni was investigated. Exposure of cultured AM to M. faeni and its CWF caused the AM to form clumps or aggregates which remained attached to the culture dish surface. Other gram-positive and gram-negative bacteria as well as yeast, zymosan, latex microspheres, and isolated peptidoglycan from Listeria monocytogenes did not cause this response. The response was independent of species source and antibody content of the serum used in culture. The use of heat-inactivated sera negated the role of complement activation in the aggregation of AM. AM cultures required a period of culture before exposure to cells or CWF for this response to occur. This response was both time and dose dependent. Rabbit peritoneal macrophages also exhibited the clumping response. Degradation of a purified CWF, fraction 3, with lysozyme greatly diminished the clumping response. Chemical purification of fraction 3 with periodate, formamide, or trichloracetic acid also decreased this activity. These data suggest that the major active component causing this response is peptidoglycan but that other materials associated with the cell wall may also be important. A soluble-factor chemotactic for normal rabbit AM was found in the culture fluid of AM exposed to fraction 3. M. faeni cells and CWF also caused normal rabbit AM to chemiluminesce.