Hepatitis C: Postpartum Is Prime Time for Exhausted T-Cell Activation

Some women have an immunity boost against hepatitis C after giving birth, and two gene variants appear to be the reason why.

“Immunity is normally exhausted in people who have chronic hepatitis C. The liver produces about a trillion viruses per day, and the T-cells that should attack the virus don’t work,” lead author, Jonathan R. Honegger, MD, principal investigator at the Center for Vaccines and immunity in The Research Institute at Nationwide Children’s Hospital in Ohio, said in a news release.

However, women with particular forms of the interferon lambda 3 (IFNL3) and human leukocyte antigen-DP beta 1 (HLA-DPB1) genes have less hepatitis C virus in the blood three months postpartum.

Honegger was studying mother-to-child hepatitis C transmission when this idea came about. He saw that some mothers had a 10- to 1000-fold drop in hepatitis C viral levels after giving birth — they also had improved T-cell activity.

Along with colleagues in Ohio and Georgia, Honegger assessed 34 women — five of which had consecutive pregnancies, as described in the Proceedings of the National Academy of Sciences of the United States of America.

“The postpartum viral load decline was very similar with each consecutive pregnancy, which made you think it wasn’t just a random event — that some stable factor was controlling how viremia fell after delivery,” Honegger explained.

IFNL3 is a signaling protein which activates antiviral activity. It’s already known to influence hepatitis C control in those who aren’t pregnant. HLA brings small pieces of protein to T-cells so that they can recognize foreign pathogens. This new research showed that women with a variant of the HLA-DPB1 gene have greater T-cell recovery. This gene’s molecules present peptides to CD4+ T-cells — a type of “helper” T-cell. It’s been thought that these helper T-cells particularly struggle with chronic hepatitis C, but this evidence suggests that they recover postpartum.

The women in this study who did not have the gene variants did not show much change in viral levels after giving birth. And while this study specifically looked at hepatitis C, the team said that it may help identify immunity boosters with other infections.

The team already studied this area further; but this time they looked at this immune effect from IFNL3 in postpartum women who did not have hepatitis C. Those results are awaiting publication.

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