Perforin is the substance T and NK cells use to drill into an infected cell and kill it. Selin and Gill’s studies suggest that ME/CFS and long-COVID patients’ T cells produce almost no perforin
https://www.healthrising.org/wp-content/uploads/2025/05/Perforin_Selin_Webinar_25.gif
[alt text: graphs of perforin in two classes of cell. The healthy controls are tall grey bars, compared to 1/10 to 1/3 as tall bars for Long COVID and ME/CFS groups.]
they also found
a huge increase in a distinct type of T-cell called double-positive T-cell (CD4+ CD8+) in people with ME/CFS and/or long COVID. Instead of being differentiated into the two usual major T-cell subsets CD4 (helper/regulatory) and CD8 (killer) T-cells, these hybrid T-cells look like both CD4 and CD8 T-cells at the same time.
Selin found that these cells increased 8-9 fold in ME/CFS and long-COVID patients.
which compensates in part for the lower perforin, but also led to
a “highly dysregulated” cytotoxic T-cell immune response [...] That suggested that the immune system was kind of flailing around, trying to come up with an answer.
from https://www.healthrising.org/blog/2025/05/15/t-cell-exhaustion-chronic-fatigue-long-covid/
#COVID #COVID19 #MECFS #LongCOVID #CovidIsNotOver #TCells #NKCells #CD8 #CD4
