We quantify how the concentration of cytokine receptors in tissue affects the extent of cell-to-cell communication. We designed a novel in vitro assay where cells are confined in a small volume to simulate the high-density conditions that typify live tissue. In such conditions, interactions are mediated by an exponentially decaying concentration field around cytokine sources, which is characterized by a Screening Length ξ. This length scale is a quantitative description of the competition between the diffusion and the consumption of cytokine. As exposure to different cytokine types and concentrations determines the fates of individual cells, the relation between ξ and other scales in the system (tissue size, cell size, etc.) would have a role in shaping the response of the immune system to different threats. We show that in the case of Interleukin-2 (IL-2) and its receptor complex, ξ changes in the range of 10-100 microns (1-10 cell diameters) and follows the theoretically predicted relation   ξ  ~  (Concentration of receptors)^-1/2.