title: Proliferation assay amplification by IL-2 in model primary and recall antigen systems.
abstract: BACKGROUND
  It can be difficult to register a weak proliferative response of T lymphocytes to an antigen, particularly in a simple culture system of peripheral blood mononuclear cells (PBMC). Here we assess the usefulness of the cytokine IL-2 in amplifying such a response.
  
  
  METHODS
  PBMC from healthy donors were cultured in the presence or absence of keyhole limpet haemocyanin (KLH), an antigen to which people have not been previously exposed. IL-2 was added from the beginning or on the fifth day of culture. Proliferation was determined by incorporation of tritiated thymidine at eight days. The recall antigen, tuberculin PPD, provided a positive control.
  
  
  RESULTS
  IL-2 added at the beginning of culture can induce extremely high levels of proliferation even in the absence of antigen. However, when added on the fifth day it allowed the clear observation of a proliferative response to KLH that was barely detectable in its absence. Added late it was similarly able to boost low responses to PPD and to the mitogens lipopolysaccharide and poly(I:C), but it had no such effect with pokeweed mitogen.
  
  
  CONCLUSIONS
  IL-2 added late in culture is highly effective in increasing the sensitivity of T lymphocyte proliferative assays.
authors.forename: Amy S M
authors.initials: AS
authors.lastname: Kennell
authors.forename: Keith G
authors.initials: KG
authors.lastname: Gould
authors.affiliation: Department of Immunology, Imperial College School of Medicine, London, UK. m.salaman@imperial.ac.uk.
authors.forename: Myer R
authors.initials: MR
authors.lastname: Salaman
mesh_terms: D000941:Antigens / Q000276:immunology*; D049109:Cell Proliferation; D006801:Humans; D007156:Immunologic Memory; D007376:Interleukin-2 / Q000502:physiology*
chemical_list: D000941:Antigens; D007376:Interleukin-2