# A mathematical model of the effects of aging on naive T-cell population and diversity

## TL;DR

This paper presents a mechanistic mathematical model to analyze how aging affects naive T-cell population and diversity, highlighting thymic output decline as a key factor in immunosenescence.

## Contribution

The paper introduces a novel quantitative model of T-cell dynamics that estimates diversity changes with age, addressing experimental challenges in full organismal analysis.

## Key findings

- T-cell diversity decreases with age due to reduced thymic output.
- Loss of small immunoclones significantly impacts overall T-cell diversity.
- The model provides quantitative estimates of T-cell population dynamics.

## Abstract

The human adaptive immune response is known to weaken in advanced age, resulting in increased severity of pathogen-born illness, poor vaccine efficacy, and a higher prevalence of cancer in the elderly. Age-related erosion of the T-cell compartment has been implicated as a likely cause, but the underlying mechanisms driving this immunosenescence have not been quantitatively modeled and systematically analyzed. T-cell receptor diversity, or the extent of pathogen-derived antigen responsiveness of the T-cell pool, is known to diminish with age, but inherent experimental difficulties preclude accurate analysis on the full organismal level. In this paper, we formulate a mechanistic mathematical model of T-cell population dynamics on the immunoclonal subpopulation level, which provides quantitative estimates of diversity. We define different estimates for diversity that depend on the individual number of cells in a specific immunoclone. We show that diversity decreases with age primarily due to diminished thymic output of new T-cells and the resulting overall loss of small immunoclones.