A novel biomarker for beryllium sensitization in humans. 1998 annual progress report

'Beryllium reactive T-lymphocytes can be used as an indicator of sensitization. Traditionally, their presence is detected by an in vitro proliferation assay. However, this test is capricious (results varying from day to day in the same laboratory) and insensitive (rarely positive before clinical symptoms ). The objective of this project is to obtain and characterize beryllium reactive T-cells from peripheral blood using the hprt T-cell mutation assay. T-cells are selected on the basis of their mutation of the hprt gene which renders them insensitive to 6-thioguanine in culture. Such mutant populations are expected to be enriched for cells which are proliferating in vivo as a result of the sensitizing process. This hypothesis has been verified in a number of studies. The seven specific aims of this study will: (i) identify the in vivo proliferating T-cell clones in sensitized individuals by selecting for hprt mutants, (ii) determine T-cell receptor (TCR) gene usages and commonalities among these clones, (iii) demonstrate reactivity to beryllium of these clones, (iv) generate beryllium sensitized T-cells in vitro from peripheral blood of the same individual, (v) determine TCR gene usages and commonalities for these in vitro derived cells, (vi) compare TCR gene patterns between the in vivo and in vitro derived clones, and (vii) develop a quantitative PCR (qPCR) method for amplifying the common (and therefore relevant) TCR genes directly from peripheral blood. The last of these is the novel biomarker of early beryllium sensitization. This report summarizes studies of the first 20 months of this project.