SERUM IGG2 LEVEL, GM(23) ALLOTYPE AND FC-GAMMA-RIIA AND FC-GAMMA-RIIIB RECEPTORS IN REFRACTORY PERIODONTAL-DISEASE

The purpose of this investigation was to compare the levels of serum I gG2, the frequency of detection of Gm(23)-negative allotype and freque ncy of detection of Fc gamma RIIa and Fc gamma RIIIb receptor haplotyp es in 32 refractory, 54 successfully treated and 27 periodontally heal thy individuals. Refractory subjects showed mean full mouth attachment loss and/or >3 sites with attachment loss >2.5 mm within 1 year after both scaling and root planing, and surgery plus systemically administ ered tetracycline. Successfully treated subjects showed mean attachmen t level gain and no sites with attachment loss >2.5 mm 1 year postther apy. Periodontally healthy subjects exhibited no pocket depth or attac hment level >3 mm, and no evidence of progressing disease during 1 yea r of monitoring. Blood was obtained from each subject at baseline. Ser um IgG2 and Gm(23) allotype were determined using radial immunodiffusi on. DNA was extracted from whole blood and the Fc gamma R genotypes de termined using PCR and allele specific oligonucleotide probes. Signifi cance of differences among clinical groups were sought using the Krusk al-Wallis or chi-square tests. Associations between 2 or more variable s were tested using regression analysis. Refractory subjects exhibited higher mean attachment loss and pocket depth than successfully treate d or periodontally healthy subjects. Smoking status did not differ sig nificantly among groups. No significant differences in serum IgG2 leve ls and frequency of detection of Gm(23)-negative allotype were observe d among the clinical groups. Serum IgG2 level was positively associate d with the number of serum antibody responses to subgingival species ( r = 0.51, p < 0.001). Subjects with the Gm(23)negative allotype exhibi ted lower mean levels of serum IgG2 (3.06 +/- 0.3 versus 3.9 +/- 0.2, p < 0.01) and mean number of serum antibodies to subgingival species ( 17.7 +/- 1.7 versus 23.3 +/- 1.4, p < 0.05) than allotype positive ind ividuals. No significant differences in Fc gamma R haplotype distribut ion were observed among the 3 clinical groups. Associations of serum I gG2 level, Gm(23) allotype, Fc gamma RIIa and Fc gamma RIIIb receptor haplotypes and smoking status were weakly related or not related to cl inical status. This lack of relationship may have been due to a realit y of no relationship, or the inadvertent pooling of subjects where the se factors were of primary importance with subjects in whom these fact ors played a less important role.