Macrophage subpopulations in gingival overgrowth induced by nifedipine and immunosuppressive medication

The immunomodulating effects of both immunosuppressive and nifedipine medication have been associated with drug-induced gingival overgrowth. The aim of the study reported here was to evaluate the presence of macrophage subpopulations in normal human gingiva and in gingival overgrowth induced by nifedipine and immunosuppressive medication.

Gingival samples were taken from 11 nifedipine-medicated cardiac outpatients (nifedipine group), 11 triple-medicated organ-transplant recipients also taking nifedipine (immunosuppression plus nifedipine group), 12 triple-medicated organ-transplant recipients (immunosuppression group), and 20 generally healthy individuals (control group). Cryostat sections were stained with mAbs for inflammatory 27E10, reparative RM3/1, and resident 25F9 macrophages using an avidin-biotin enzyme complex method. Total numbers of mAb-labeled cells were determined in connective tissue beneath sulcular epithelium, connective tissue beneath oral epithelium, and middle connective tissue. Expression of 27E10 was determined in keratinocytes in the oral epithelium. Statistics analyses were undertaken using the chi-square test, the Mann-Whitney U test, the independent samples t test, analysis of variance, and analysis of covariance.

Greater numbers of inflammatory 27E10-positive macrophages were found in all 3 medicated groups and counting zones than in the control group except in connective tissue beneath sulcular epithelium in the immunosuppression group. The incidence of specimens expressing 27E10 antigen throughout the oral epithelium was significantly higher in the immunosuppression group (8 of 12) than in the control group (4 of 20) and the nifedipine group (2 of 11). Numbers of reparative RM3/1-positive macrophages were significantly greater in the immunosuppression group in connective tissue beneath oral epithelium than in the control group. The effect was markedly associated with degree of inflammation. Numbers of resident 25F9-positive macrophages were lower in connective tissue beneath sulcular epithelium in the immunosuppression group, and higher in middle connective tissue in the nifedipine group than in the control group.

Our results show that the nature of drug-induced gingival overgrowth differs somewhat between immunosuppressive and nifedipine medications.