Immunity affects Pap smears in HIV-infected women

Human papillomavirus (HPV), a virus that has been linked to Cervical cancer, can lie dormant for a long time, but re-emerge if the immune system is weakened, new research shows.

The likelihood that HPV will be detected on a Pap smear in HIV-infected women depends on the patient's immune status, according to the study. In particular, HPV is unlikely to be detected if HIV levels are low and CD4+ T cells, a type of immune cell, are abundant.

"Our data suggest that undetectable HPV infections become active much more frequently in HIV-positive women, which helps explain the extremely high rates of HPV infection in these women," lead author Dr. Howard D. Strickler, from the Albert Einstein College of Medicine in New York, said in a statement.

"By extension, our findings suggest that HIV-positive women and other women with poor immune status, such as transplant patients, may benefit from continued (Pap testing) even if they've long been celibate, since old HPV infections can rise again," he added.

Strickler's team analyzed data from 1848 HIV-positive and 514 HIV-negative women to assess factors that influence HPV detection. The findings are published in the Journal of the National Cancer Institute.

As noted, the HIV level and the CD4+ cell count were strongly linked to HPV detection. Also, pre-cancerous lesions were less likely to be found among women with low HIV levels and high CD4+ cell counts, an indication that the immune system is still working.

Consistent with previous reports, in all women, the likelihood of detecting HPV rose as the number of recent sexual partners increased, the authors point out.

SOURCE: Journal of the National Cancer Institute, April 20, 2005.