Immune cell clones grow unevenly after infection

Natural killer cells (NK cells) are part of the innate immune system. They recognise and eliminate infected cells without prior exposure to the pathogen. But in mice infected with cytomegalovirus (a common herpesvirus), NK cells do something notable: they expand in an antigen-specific manner, similar to T cells from the adaptive immune system. The researchers published their findings in eLife and studied how this growth profile arises.

Maturation and division work together

The analysis shows that variation in clone size is not random. Mature NK cells with the CD27-negative marker divide faster than less mature variants. A specific subgroup (CD27-negative and Ly6C-negative) was particularly active in division. The interplay between cell division, cell death and maturation together determines how a clone expands.

The researchers also found that viral infection increases only the division rate of NK cells, not the rate at which they mature. This differs from T cells, where the maturation tempo also changes during infection.

What does this mean for immune aging?

The study was conducted in mice and focuses on a specific infection. Translation to humans requires further research. Even so, the finding is relevant to longevity science, because the immune system changes substantially with age. NK cells progressively lose part of their function as we get older, contributing to increased vulnerability to infections and cancer in later life.

Understanding the rules that govern how NK cell clones grow and mature is a first step toward explaining why that process changes with aging. Whether this type of knowledge will eventually lead to interventions that improve NK cell responses in older people remains speculative for now.

Read the original article