New research has uncovered a relationship between hormone levels in women and the production of antibodies in response to hepatitis B vaccination. The study, recently published in Adaptive Human Behavior and Physiology, found negative associations between testosterone and immune responses, and positive associations between estradiol and immune responses.
“The association between steroid sex hormones and immune responses is an exciting area of research as there is still so much to study,” said study author Javier I. Borráz-León of the University of Turku and The Institute for Mind and Biology at the University of Chicago.
“For this reason, we wanted to contribute with this research by studying the association between two sex hormones (i.e., testosterone and estradiol) and the production of antibodies against hepatitis B in young-healthy women, in whom, by the way, even less is known than is known in men regarding this association.”
The study examined 55 healthy young Latvian women to received two doses of a hepatitis B vaccine. To assess hormone levels and the production of antibodies, the researchers collected blood samples at three time points: Before the first vaccination, one month after the first vaccination, and one month after the second vaccination.
The researchers found that higher testosterone levels among the women were associated with a reduced immune response one month after the first vaccination. The findings are in line with previous research, which has suggested a “potential suppressive effect of T levels on antibody production, or a potential suppressive effect of immune response on T levels,” the researchers said. In contrast, higher estradiol levels were associated with a heightened immune response one month after the second vaccination.
“I think our findings allow us to highlight sex differences in immune function and its association with sex hormones,” Borraz-Leon told PsyPost. “Since women have significant hormonal fluctuations throughout their menstrual cycle, we consider it extremely important to consider the sex of the individual as an important factor when conducting an experiment of this type as well as when interpreting the results.”
The researchers also observed a tendency for a decrease in testosterone between the first vaccination and one month after the second vaccination, while significant changes in estradiol levels were not observed over the three time periods.
“We think it is very interesting to have been able to observe the changes in the concentration of testosterone (but not estradiol) with respect to the production of antibodies against hepatitis B in women,” Borraz-Leon said. “Why only testosterones but not estradiol? This is a question worthy of being answered in future studies.”
“One of the questions that we consider most interesting to answer is: how is the interaction between the endocrine system and the immune system?” the researcher added. “That is, how does the production of hormones directly affect the production of antibodies (and other immunological markers) and, in turn, how does the production of immunological markers regulate hormone production?”
The study, “Testosterone, estradiol, and immune response in women“, was authored by Javier I. Borráz-León, Severi Luoto, Indrikis A. Krams, Markus J. Rantala, Giedrius Trakimas, Sanita Kecko, and Tatjana Krama.