Abstract Body

Based on cytokine expression T_h-cells can be subdivided in multiple subsets. This has helped to further unravel the pathogenicity of many immune-mediated diseases. However, the distinction between subsets is rather artificial and, therefore, there is a need for an holistic view on the T_h-cell compartment. Since successful mechanisms seem to be conserved in nature, analogies were searched for and found in the form of clouds of starling and schools of herrings. Also for the T_h-cell compartment it might be better to consider it as a continuum that is able to move freely within well-defined limits in order to optimize immunity and prevent excessive pathogenic responses. Neighboring cells will, like the starlings and herrings, influence the direction of T_h-cell differentiation. The limits of movement may be typically controlled by T_reg. The challenge of this model is to define a grading system that, first, represents the skewing of the T_h-cell compartment, and, second, that indicates if the T_h-cell compartment has passed the limits of plasticity and homeostasis.