The histoimmunological response of 8 individuals was studied longitudinally in relation to the development of experimental gingivitis during pregnancy and post-partum. At day 0 as well as at day 14 of experimental gingivitis the mean periodontal pocket bleeding index (PPBI) was higher during pregnancy than post-partum, whereas the amount of plaque that accumulated was similar. The number of CD1 positive cells (mainly Langerhans) in the oral epithelium was found to be higher during pregnancy. In the sulcular epithelium, however, the number of these cells tended to decrease during pregnancy as compared to post-partum. The number of CD4 positive cells in oral and sulcular epithelium was increased during pregnancy (P < 0.05). It was speculated that this increase in the number of CD4 positive cells is confined to the Th-1 subset, since the number of CD14 positive cells (mainly macrophages and granulocytes) together with the number of B cells was found to be decreased during pregnancy. Th-1 cells are known to be cytotoxic against these HLA class II antigen bearing cells. Consequently, cytotoxicity directed against B cells and macrophages may result in diminished immunoresponsiveness in pregnancy gingivitis.

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