What cell type is primarily lost in cats suffering from lymphopenia due to Feline Leukemia Virus (FeLV) or Feline Immunodeficiency Virus (FIV) infection?

In cats suffering from lymphopenia caused by Feline Leukemia Virus (FeLV) or Feline Immunodeficiency Virus (FIV) infection, the primary cell type that is lost is the CD4+ T cells. CD4+ T cells are a crucial component of the immune system, serving as helper cells that assist in orchestrating the immune response. They are key players in recognizing antigens and helping activate other immune cells, including B cells and CD8+ T cells.

Both FeLV and FIV target and infect the immune system, leading to a decline in CD4+ T cell populations. This depletion contributes to the compromised immune function observed in infected cats, making them more susceptible to opportunistic infections and diseases. Understanding this loss of CD4+ T cells is vital for diagnosing and managing the health of cats affected by these viral infections.

Other cell types mentioned, such as CD8+ T cells, B cells, and natural killer cells, may also be affected by these infections, but the notable loss of CD4+ T cells is particularly significant and directly impacts the overall immune response. The decline in CD4+ T cells not only leads to lymphopenia but also results in a dysregulated immune status, emphasizing the importance