Disturbed PMN/monocyte chemotactic function has been consistently demonstrated in K localized juvenile periodontitis (LJP) or generalized juvenile periodontititis (GJP) syndromes, but molecular pathogenic mechanisms underlying these cellular abnormalities have not been fully elucidated. Recent studies have identified a newly recognized genetic disorder characterized by recurrent soft tissue infections (including severe prepubertal generalized periodontitis), and severe deficits of PMN/monocyte chemotaxis and other adherence-dependent cellular functions which are causally related to a deficiency of a family of "adhesive' glycoproteins (Mac-1 [IC3b receptor], LFA-1, and p150, 95) expressed on leukocyte surfaces. The proposed studies will evaluate: (1) potential intrinsic abnormalities of expression/function of Mac-1 glycoproteins of LJP of GJF leukocytes, and (2) possible pathologic effects of microbial products on Mac-1 proteins. Adherence-dependent PMN/monocyte functions (chemotaxis, aggregation, IC3b phagocytosis or cytotoxicity) will be assessed under chemotactic conditions designed to maximize Mac-1 and p150,95 surface expression. These studies will be related to quantitative assessments of surface protein expression employing specific monoclonal antibodies (MAb) in immunofluorescence flow cytometry and 125I immunoprecipitation techniques. Since our preliminary studies indicate impaired stimulated Mac-1 expression and hyperadherence of LJP PMNs, additional techniques will be used to quantitate intracellular pools of Mac-1 proteins in cellular fractions (conconavalin A - immunoblot technique) or biosynthesis of these molecules in EBV-transformed lymphocytes (35S methionine labeling). Applications of anti-Mac-1 MAbs will attempt to identify affected patients or heterozygotes among LJP kindreds which may allow an elucidation of the genetic transmission of disease. Possible secondary influences of "periodontopathic" microorganisms on Mac-1 glycoprotein expression will also be evaluated; normal PMN/monocytes will be incubated with culture filtrates or sonicates of Actinobacillus actinomycetemcomitans, Bacteroides and Capnocytophaga sp. in chemotaxis and other adherence-dependent functional assays, and concurrently assessed with respect to expression, function or induction of Mac-1. Our studies should extend previous experimental observations by: (1) providing a molecular basis for impaired chemotaxis and other abnormalities of leukocyte function among LJP kindreds, (2) delineating intrinsic (genetic) and/or secondary pathologic mechanisms and (3) providing a molecular marker for identification of affected individuals or heterozygotes for LJP or GJP traits.