Hypersensitivity to beryllium (Be) is found in 1-16% of exposed workers undergoing immunological screening for beryllium disease using the beryllium lymphocyte proliferation test (BeLPT). However, only approximately 50% of BeLPT-positive workers present with lung granulomas (i.e. berylliosis). As berylliosis is associated with the human leukocyte antigen (HLA)-DP supratypic marker DPGlu69, the authors asked whether this marker is differentially associated with disease presentation. A population of 639 workers from a beryllium factory undergoing BeLPT screening was evaluated in a nested case-control study for the prevalence of HLA-DPGlu69, the HLA-DPB1, HLA-DQ and HLA-DR alleles and of the biallelic tumour necrosis factor (TNF)-alpha polymorphism TNF-alpha-308 in 23 individuals presenting as "sensitized" (i.e. BeLPT-positive without lung granulomas) and in 22 presenting as "diseased" (i.e. BeLPT-positive with granulomas in the lung biopsy). The HLA-DPGlu69 marker was associated with "disease" (odds ratio (OR) 3.7, p=0.016, 95% confidence interval (CI) 1.4-10.0), whilst the high TNF-alpha production-related TNF-alpha-308*2 marker was associated with both a positive BeLPT (OR 7.8, corrected p<0.0001, 95% CI 3.2-19.1) with no difference between "sensitization" and "disease". Furthermore, the HLA-DRArg74 marker was associated with "sensitization" without disease (OR 3.96, p=0.005, 95%, CI 1.5-10.1). The data indicate that tumour necrosis factor-alpha, human leukocyte antigen-DR and human leukocyte antigen-DP markers play different roles in beryllium sensitization and granuloma formation in beryllium-exposed workers.