Lymphocyte transformation test

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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LTT; lymphocyte transformation test; Lymphocyte transformation test

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In vitro test with stimulation of lymphocytes by mitogens for the clarification of immune defects or with allergens for the detection of specifically sensitized lymphocytes, e.g. in case of drug allergies. After stimulation, conversion of small resting lymphocytes to large activated lymphoblasts, as demonstrated by the increased incorporation of radioactively labelled nucleic acids. The lymphocyte transformation test detects a very early phase of the immunological reaction (antigen presentation and antigen recognition).

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  • The lymphocytes are separated from the blood cells by centrifugation and several washing processes.
  • Then a nutrient solution and the antigen to be tested are added.
  • Same procedure as the control sample, but without the addition of antigen.
  • Then incubation of the cultures for several days.
  • 16 hours before evaluation addition of radioactive thymine.
  • Thymine is necessary as a substrate in the synthesis of DNA.
  • Measurement of the radioactivity of the lymphocyte culture and calculation of a stimulation index.
  • A stimulation index > 3 is usually considered positive in practice and indicates that sensitized lymphocytes were present in sufficient quantities in the blood and have undergone a transformation.

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  1. Bussa S et al (1993) Evaluation of a new whole blood cytometric lymphocyte transformation test for immunological screening. J Clin Lab Immunol 40: 39-46
  2. Kano Y et al (2007) Utility of the lymphocyte transformation test in the diagnosis of drug sensitivity: dependence on its timing and the type of drug eruption. Allergy 62: 1439-1444
  3. Merk HF (1988) In vitro diagnostics for drug allergies. Allergology 11: 57-59


Last updated on: 29.10.2020