The broad objective of this proposal is to identify the molecular mechanisms which PMN normally utilize to control specific periodontal pathogens and to examine factors which control the spectra of antimicrobial activity exerted by these mechanisms. the specific research aims are: (1) to determine how normal human PMN kill periodontal pathogens under aerobic and anaerobic conditions to classify which type of mechanism is involved in killing by intact cells: (2) PMN bactericidal proteins, peptides, and enzymes will be purified by fast protein liquid chromatography (FPLC) or high pressure liquid chromatography (HPLC); (3) monoclonal and polyclonal antibodies will be developed against bactericidal substances to detect bound ligand in binding analyses and to inhibit ligand binding and bactericidal activity in studies designed to verify the role of binding in the killing process. Binding will be analyzed by enzymatic, immunoenzyme, or radioimmuno procedures, (4) binding topography will be determined by electron microscopy and autoradiography of SDS-polyacrylamide gel electrophoresis of bacterial surface substances tagged using potoaffinity probes such as radioiodinated sulfosuccinimidyl - 2 - (p - azidosalicylamido) - ethyl - 1, 3'- dithiopropionate; (5) Interactions among the bactericidal substances will be determined by microdilution assay and isobologram analysis.