A study of antibody-producing B cells from patients who recovered from COVID-19 reveals a new cross-reactive antibody and what makes some B cells more effective at neutralizing the virus.
“[The adaptive immune system] has this special feature of memory, which is what you exploit in vaccines,” said Prof Danny Altmann, an expert in immunology of infectious disease at Imperial College London.
It involves two main types of white blood cells, known as lymphocytes. B cells produce antibody proteins that can stick to the virus to prevent it from entering cells. T cells kill virus-infected cells and make proteins called cytokines.
In this work, we demonstrate that spike-specific memory B cells, capable of reactivation following antigen encounter, persist in the blood of vaccinated subjects 6 months after the administration of the BNT162b2 SARS-CoV-2 mRNA vaccine. Concomitant to antibody reduction, spike-specific memory B cells, mostly IgG class-switched, increase in the blood of vaccinees and persist 6 months after vaccination.
We've seen many studies of antibody titers and the like over time, but this is going to a deeper level and looking at the actual memory B cells. Those, you may well recall or already know, are the ones that persist and stay on guard should the same antigens reappear. They can go on for decades as an inbuilt surveillance system, ready to expand and start the antibody production process again if a similar immunologic threat shows up again.
Antibodies are great and all, but macrophages, B cells, and helper T cells deserve some attention too.
In the 1960s, immunologists found that chickens which had their bursa – a major immune organ in birds – destroyed with radiation, lacked certain cells necessary to produce antibodies. These became known as Bursa-derived cells or B cells. By the mid 1970s, it was discovered that these cells form in humans in the bone marrow, before migrating to the lymph nodes or the spleen.