Immunological and Serological Aspects of Human Papillomavirus Infection in Finnish Mothers and Their Children

Human papillomavirus (HPV) infects cells of the cutaneous and mucosal epithelia. Most HPV infections are transient and subclinical as they are eliminated by an efficient host immune response. On the other hand, an insufficient immune response may result in persistency and progression of an HPV infection, which may even lead to development of cancer. As HPV infection can be transmitted vertically from a mother to her child, HPV infection may be acquired already at early age.

This thesis is part of the longitudinal Finnish Family HPV Study. The general objective of the present study was to further investigate HPV-related immunology and serology in Finnish mothers and their children. The specific aims of the present study were to characterize peripheral blood T lymphocyte immunophenotypic subsets regarding HPV16 infection status of the mothers and the corresponding effects on their children; to determine maternal antibodies against HPV6 early and late proteins and corresponding HPV seroconversion in children in their early infancy; and finally to evaluate the effect of pregnancy on the seropositivity and antibody levels for HPV types 6, 11, 16, 18, and 45.

Results on T lymphocyte immunophenotypic subsets revealed differences as related to the mother’s HPV16 infection status at either genital or oral site. Both genital and oral HPV16 infection were associated with alterations in the peripheral blood T lymphocyte subsets in the mothers. In the children, alterations in the T lymphocyte subsets were observed only in those children whose mother had the persistent oral HPV16 infection. Furthermore, results on HPV6 antibodies against both HPV early and late proteins indicated that there was a clear correlation between maternal and neonatal HPV6 antibodies. After the decay of maternal HPV6 antibodies, seroconversion against HPV6 L1, E2, E4, E6, and E7 proteins did occur in early childhood during the follow-up. Finally, the results of the present study showed that seropositivity for HPV types 6, 11, 16, 18, and 45 was less common in the women who developed second pregnancy than in those who did not.

These results support the view that the mother’s HPV infection affects the immune system of her offspring. In addition, these results are in line with that HPV infection may be acquired in early childhood, potentially via vertical or horizontal transmission.