Objective: To investigate the effects of stopping smoking on cervical Langerhans' cells and lymphocytes.
Design: Prospective intervention study.
Setting: A large family planning clinic in central London.
Population: Women volunteers prepared to attempt to give up smoking for six months. Their most recent cervical smear showed no abnormality greater than mild dyskaryosis.
Methods: The women were seen at three-month intervals for six months. Reduction in smoking was assessed by self-reporting and validated by salivary cotinine concentrations. Colposcopy and a biopsy of a normal area were performed at the first and last visits. Any area of abnormality was also biopsied at the final visit. Langerhans' cells and lymphocytes were counted.
Main outcome measures: Proportional changes in counts of Langerhans' cells and lymphocytes with reduction in smoking.
Results: Reduction in smoking by 20 to 40 cigarettes per day was significantly associated with a reduction of between 6% and 16% in counts of Langerhans cells, CD8 and total lymphocytes. Heavy smoking was significantly associated (P = 0.02) with an increased chance of persistent human papillomavirus infection. The presence of candida was associated with significantly higher counts of between 41% and 47% in total lymphocytes and CD8 lymphocytes. In contrast, the presence of anaerobic vaginosis was associated with significantly lower counts of between 16% and 30% in Langerhans cells, CD4 and CD8 lymphocytes.
Conclusions: This large intervention study has demonstrated a clear relationship between reduction in smoking and changes in cervical immune cell counts. Future studies need to take into account cytokine interactions, which recent studies suggest may be significant in the immune response to both human papillomavirus and cervical intraepithelial neoplasia and the ever-increasing complexity of the cell-mediated immune system of the cervix.