Quantitation of soluble HLA class I heterodimers and beta 2-microglobulin in patients with active pulmonary tuberculosis.

Beta 2m serum levels have been shown to be increased in patients with tuberculosis and HIV infection. We determined the stability of beta 2m and of sHLA-I dimers in serum, and then determined the levels of both molecules in 60 non-HIV-infected patients with active pulmonary tuberculosis and in 55 adult controls. The levels of sHLA-I in samples kept at room temperature declined by 8% at 30 minutes, 16% at 60 minutes, and 36% at 120 minutes. Beta 2m levels remained stable at all times tested. Mean sHLA-I levels were 0.99 +/- 0.16 micrograms/ml in controls and 1.34 +/- 0.11 micrograms/ml in patients with tuberculosis (P < 0.0001). Beta 2m levels were 1.23 +/- 0.26 micrograms/ml in controls and 2.26 +/- 0.64 micrograms/ml in patients with tuberculosis (P < 0.0001). All patients with tuberculosis had elevation of sHLA-I and/or beta 2m above 1 standard deviation of normal values. However, there was no correlation between sHLA-I and beta 2m levels in individual samples. Evaluation of sHLA-I holds the promise of further understanding of the biology and genetic regulation of the immune response to mycobacterial infection.