In many people, antibodies may not be the superstars of lasting immunity against the virus that causes COVID, according to recently published research (January 2021) from a German university, which suggests T cells may be the key to lasting immunity.
In this study, 78% of volunteers for convalescent plasma donations, who had been confirmed positive via PCR testing for the SARS-CoV2 virus, did not have detectable antibodies in their blood. However, all of them did show T-cell immunity against this virus, suggesting that people are often immune to the virus even in the absence of antibodies.
In fact, they demonstrate this is quite common, suggesting T cell immunity may be more important than B cell immunity.
The absence of IgG antibodies against SARS-CoV2 may indicate that the virus was cleared effectively by a healthy, well-functioning cell-mediated immune system, namely T cells.
A short primer on T cell and B cell immunity is appropriate here for the non-medical folks. Both T and B cells are types of lymphocytes (white blood cells) that protect a person from viruses, although they work in very different ways. T cells work by signaling other cells how to handle a virus. For example, they tell some immune cells to release chemicals that kill infected cells or damage the virus directly. In a healthy person, T cells are highly adaptable and can adjust to their environment. They can both induce and quell inflammation, depending on what is needed to protect the host. Ideally, T cells should be able to multiply easily, thus increasing a person’s immunological army, so to speak. B cells, on the other hand, work by creating antibodies, which ultimately bind with a virus in order to inactivate it.
The key to lasting immunity is “cellular memory.” Both types of lymphocytes – T and B cells – have the ability to remember viruses. If a virus is re-introduced in the future, the cells already know what to do and can stop the virus in its tracks before it wreaks havoc on the body.
People tend to think of antibodies as the main protection against re-infection, but according to this study and other published data, antibodies often wane after a few months, and another mechanism of “cell memory” is at play. This “memory” comes from T cells, according to this study. The implication is that T cell health is a key factor in protection from COVID-19, perhaps more so than antibodies. In fact, the authors unequivocally state “immunity may be mediated through T cells” and that “SARS-CoV2 specific T cells were detectable in the majority of recovered patients.”
Spectracell measures T-cell function in a test called the Immunidex.
(Emerging Infectious Diseases, January 2021)
