News Excerpt:

An analysis of blood samples from 55 patients diagnosed with Long COVID has revealed that they experienced prolonged elevated levels of an anti-viral protein interferon-gamma, which persisted for 180 days post-infection.

• This effect was induced by CD8 “killer” T cells in response to antigens present in the patients’ CD14 cells. 

More About the news:

• The findings highlight an immune response to SARS-CoV-2 infection associated with long COVID’s debilitating symptoms.

About Long COVID:

• Long COVID is defined as symptoms or conditions that last more than 12 weeks after initial infection with COVID-19. 
• It has become a growing burden for public health systems since the emergence of the coronavirus pandemic four years ago. 
• Sufferers report an array of symptoms, including acute fatigue, shortness of breath and cognitive impairment or “brain fog”.

About anti-viral protein interferon-gamma (IFN-γ):

• The researchers found that COVID-19 infection triggered IFN-γ production by white blood cells, which persisted in the long Covid patient cohort.
• IFN-γ is important in regulating the body’s response to pathogens. 
• It is used clinically to damp infections in people whose immune systems have been compromised by chronic granulomatous disease, a genetic disorder that makes people susceptible to dangerous bacterial and fungal infections.

About T cells:

• T-cells are a type of white blood cell called lymphocytes. 
• They help our immune system fight germs and protect us from disease. 
• There are two main types -
  • Cytotoxic T-cells: 
    • Cytotoxic T-cells are also called CD8+ cells because they have a CD8 receptor on their membranes. 
    • These cells get their name from “cyto,” which means cell, and “toxic,” which means poisonous or harmful. 
    • Cytotoxic T-cells kill cells infected with viruses and bacteria and destroy tumour cells.
  • Helper T-cells: 
    • Helper T-cells are called CD4+ cells because they have a CD4 receptor on their membranes. 
    • Unlike cytotoxic T-cells, helper T-cells don’t kill cells directly. 
    • Instead, they send signals that tell other cells in our immune system how to coordinate an attack against invaders. 
    • Helper T-cells signal cytotoxic T-cells, B-cells, and another type of white blood cell called a macrophage.

• Location of T-cells: T-cells start in our bone marrow, mature in our thymus and eventually relocate to our lymph tissue or bloodstream.

• Bone marrow: 
• T-cells start in the spongy tissue inside our bone called marrow. 
• Like all blood cells, they start as hematopoietic stem cells. 
• These cells have the potential to develop into any type of blood cell.
• Thymus: 
• T-cells move to an organ called our thymus (located in our upper mid-chest) to mature. 
• At this stage, the immature T-cells are called thymocytes. Our thymus is like a boot camp for T-cells. 
• They also receive the right receptor, either CD4 (helper T-cells) or CD8 (cytotoxic T-cells). 
• Only T-cells that pass all these tests go out into our body.
• Lymph tissue and bloodstream: 
• Fully mature T-cells travel to tissue and organs in our lymph system, like our spleen, tonsils and lymph nodes. 
• They may also circulate in our bloodstream. T-cells remain on standby in our body until we need them to protect us.