Results of a new study suggest that people with HIV who begin antiretroviral therapy soon after infection may better retain the ability to fight off other infectious diseases than people who begin treatment later.

“Our work…suggest[s] that more clinical trials should be aimed at comparing early-treated and chronic-treated patients by a variety of different immunologic parameters,” said Dr. Susan Moir, lead author of the study, in correspondence with The AIDS Beacon.

The findings shed light on a group of immune cells called B cells and how early initiation of antiretroviral therapy (ART) may help prevent irreversible damage to the immune system.

B cells are a type of immune cell. They make antibodies, proteins that help the immune system identify and fight infectious pathogens like bacteria and viruses.

Memory B cells are a special type of B cell that are formed after infection with a pathogen. Their role is to remember how to make antibodies to that particular kind of virus or bacteria.

Memory B cells are the reason a person who catches an illness, like the chicken pox, becomes immune to it thereafter. Vaccines work by prompting memory B cells to make antibodies to the virus or bacteria from the vaccine, creating immunity.

In contrast, “exhausted” B cells are nonfunctional and cannot produce antibodies.

In this study, scientists measured the amount and type of B cells in blood samples taken from three groups of men. The first (“early treatment group”) contained men who had been HIV positive for six months or less and had not yet started ART. The second group (“late treatment group”) had been HIV positive for a while, in some cases several years, but had also not yet started ART. The third group contained men who were HIV negative.

At the start of the study, all the men who had HIV started taking antiretroviral therapy.

Results showed that at the start of the study, both groups of HIV-positive men had fewer B cells in their blood than the HIV-negative men. Once the two groups of HIV-positive men began ART, the number of B cells in their blood began to rise in a similar manner.

However, the types of B cells in the two HIV-positive groups differed significantly throughout the study.

Men who started antiretroviral therapy early were able to achieve numbers of memory B cells similar to those in HIV-negative men; men who started treatment late, however, continued to have low levels of memory B cells. Furthermore, men who started treatment late had greater numbers of immature B cells, while men who started ART early were able to reduce their levels of undeveloped B cells to those of HIV-negative men.

The late-treatment group also had significantly more exhausted B cells than the other two groups of participants, even after one year of ART.

To investigate how these differences in the types of B cells present affected the immune system, researchers also examined how the two groups of HIV-positive men responded to an influenza vaccine at the start of the study and one year after beginning ART.

Results showed that one year after starting antiretroviral therapy, men who had started treatment early had a greater number of B cells that successfully made anti-influenza antibodies compared to the late-treatment group.

This suggests that starting antiretroviral therapy early in the course of HIV infection allows patients to better fight off other infections than if they start ART later.

Dr. Moir said follow-up studies are planned but noted that it is difficult to find eligible participants. Most people who have had HIV for a while stay current on their vaccines, while those who have just been diagnosed usually receive the vaccines when they start ART.

“[This] means we cannot measure the before and after effects of ART on vaccination response,” said Dr. Moir.

“We are nonetheless continuing to investigate these questions and trying to find simpler schemes. We also continue to measure responses to HIV itself, which also differed between the two groups,” she added.

The idea of starting ART early is a controversial one, due to possible long-term side effects of antiretroviral drugs. A different clinical trial testing the effects of starting HAART when a person’s CD4 (white blood cell) count drops below 500 cells per microliter – earlier than the current recommendation of 350 cells per microliter – is currently underway.

The study, named Strategic Timing of Antiretroviral Treatment (START), is a joint effort by the University of Minnesota, the National Institutes of Health, various European HIV institutes, and several pharmaceutical companies.

The study is currently recruiting participants.

For more information, please see the study in the journal Blood (abstract). For more details on the START study, please see the clinical description at the United States Clinical Trials registry.