We analyzed the cell-cell adherence related to CD11/CD18 and CD18 mRNA in individuals with decreased CD11/CD18 expression on their neutrophil surface. Epstein Barr virus-transformed B cell lines were developed from one localized juvenile periodontitis (LJP) patient with decreased CD11/CD18 in the peripheral blood neutrophils and without systemic diseases; two siblings with generalized prepubertal periodontitis (GPP) caused by leukocyte adhesion deficiency (LAD); another LJP patient; one localized prepubertal periodontitis (LPP) patient; and two healthy subjects. Adhesion of leukocytes to each other was measured as cluster formation by aggregation assay. The length and the amount of CD18 mRNA expressed in the cell lines were analyzed by Northern blotting using the 32P-labeled CD18 cDNA. The coding region of the mRNA was analyzed by the reverse transcription-polymerase chain reaction method. Base-mismatches between CD18 mRNA and the 32P-labeled RNA probe synthesized from CD18 cDNA were analyzed by RNase protection assay. In the adherence assay, cells from the LJP patients with decreased CD11/CD18 formed more clusters of smaller size and fewer cells than those of the other subjects. The cells from GPP and LAD patients did not aggregate and did not form clusters either in the absence or presence of PMA. There were no differences in the length and the amount of mRNA between the LJP patients and the other subjects, while GPP-LAD patients expressed a small amount of long mRNA. The whole coding region (2,313 base pairs) of all subjects was amplified except for the GPP-LAD patients, and the 5'-region (1,119 base pairs) was amplified from all subjects.(ABSTRACT TRUNCATED AT 250 WORDS)