title: Interleukin 15 is a potent stimulant of intraepithelial lymphocytes.
abstract: OBJECTIVE
  This study examined the effects of interleukin (IL)-15 on intraepithelial lymphocytes (IELs) because they resemble memory cells that react to IL-15 and are located next to epithelial cells that produce IL-15.
  
  
  METHODS
  Proliferative responses were measured by [3H]thymidine uptake; interferon (IFN)-gamma production by enzyme-linked immunosorbent assay; and cytotoxicity production by lysis of 51Cr-labeled HT-29 cells.
  
  
  RESULTS
  The proliferative response of IELs was much greater with IL-15 than with equivalent amounts of IL-2 or IL-7 (P < 0.001); the same level of blastogenesis was induced by 10(3)-fold less IL-15 than IL-2. Production of IFN-gamma was also highest when IELs were stimulated with IL-15. IELs lysed more 51Cr-labeled HT-29 cells when cultured for 72 hours with IL-15 (48% +/- 3% at 25:1 effector-to-target ratio) than with IL-2 (27% +/- 3%) or IL-7 (12% +/- 2%) (P < 0.0001). Similarly, limiting dilution analysis revealed a greater frequency of cytotoxic precursors in IELs that were stimulated by IL-15 rather than IL-2: 1/467 vs. 1/1900. But IL-15 did not alter the number of natural killer cells, as determined by quantitating CD16 and CD56 by immunofluorescence. Rather, it increased serine esterase content in IELs.
  
  
  CONCLUSIONS
  IL-15 is the most potent of the known cytokines for IELs, inducing the highest levels of proliferation, IFN-gamma production, and cytotoxicity.
authors.affiliation: Department of Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA.
authors.forename: E C
authors.initials: EC
authors.lastname: Ebert
mesh_terms: D002455:Cell Division; D003602:Cytotoxicity, Immunologic; D004848:Epithelium; D006801:Humans; D016130:Immunophenotyping; D019409:Interleukin-15 / Q000502:physiology*; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology / Q000502:physiology*
chemical_list: D019409:Interleukin-15