Diagnostic relevance of the lymphocyte transformation test for sensitization to beryllium and other metals (IUPAC Technical Report)

The lymphocyte transformation test (LTT) has been proven useful especially in the diagnosis of drug-induced allergic disorders. It is an in vitro test which is based on the fact that lymphocytes, which have been sensitized by a certain antigen, transform into blasts and proliferate when they are again exposed to this antigen. This proliferation is determined by measurement of the incorporation of [H-3]-thymidine or bromodeoxyuridinc into replicating DNA. The test has the advantage over skin tests of avoiding re-exposure of individuals, and it was, therefore, hoped that it may also help to diagnose metal allergies and especially sensitization toward beryllium. However, the LTT measures only the sensitization of lymphocytes, but not the effector reaction, i.e., there may be positive results in exposed individuals even in the absence of clinical symptoms. There are several reports evaluating the LTT toward gold salts (An), amalgam (Hg), nickel (Ni), beryllium (Be), and several other metals. With metals other than Be, the LTT appears to be of little use. In contrast, the LTT with Be may, indeed, define patients at risk of developing chronic beryllium disease (CBD), which affects mainly the respiratory tract and may even cause death. Beryllium sensitization progresses to CBD at a rate of 7-11% per year. Since the Be-LTT can detect sensitization in workers who have not yet developed a disease it is an important diagnostic tool to detect individuals at risk. In conclusion, the LTT can detect a cell-mediated immunological response of an individual to metals. However, for most metals its usefulness is questionable, with the exception of Be; a positive Be-LTT can identify not only patients with CBD, but also persons at risk of developing CBD in later years.