PURPOSE: Elevated levels of HLA proteins in peripheral blood and other body fluids have been reported in several pathologic conditions that are associated with increased concentrations of white blood cells such as infections, inflammation and lymphoproliferative disorders.In this investigation we measured soluble HLA class II proteins (sHLA II) in peripheral blood of patients with Alpha 1 antitrypsin deficiency (A1ATD) with and without co-existing COPD.
METHODS: Three groups of patients were investigated: 1. Fifty-five patients with A1ATD and COPD, 22 females, 33 males, age: age: 50.2 ± 1.2 years. 2. 18 patients with COPD and normal A1AT, 9 females, 9 males, age: 49.3 ± 2.4 years. 3. 9 patients with A1ATD and no COPD, 8 females, 1 male, age: 45.9 ± 6.1 years. 4. 37 normal blood donors, 16 females, 21 males, age: 37.8 ± 2.6 years. A sensitive ELISA was developed to measure sHLA. As standard we used a secreted class II HLA-DRB1*0103 produced by PURE Protein, LLC.
RESULTS: We found sHLA II plasma levels in patients with A1ATD and COPD (Group 1) and those with A1ATD alone (Group 3) to be 0.11 ± 0.03 ng/ml and 0.07 ± 0.03 ng/ml respectively, and significantly (p=0.0013 and p=0.0084) above the levels of the healthy controls (Group 4) and the COPD patients(Group2). The sHLA II levels in COPD patients (group 2) and healthy blood donors were both low 0.01 ± 0.005 ng/ml and 0.01 ± 0.003 ng/ml, and not significantly different from each other(p=0.76).
CONCLUSION: Our results suggest that in A1ATD elastase and other proteinases may cut HLA proteins from cell surfaces and contribute to the plasma levels of HLA proteins. This effect would be expected to be greater in the absence or with low levels of the antiproteolytic protection by A1AT.
CLINICAL IMPLICATIONS: Elevated soluble HLA protein levels may be an indicator of cell damage in A1ATD.
DISCLOSURE: Friedrich Kueppers, No Financial Disclosure Information; No Product/Research Disclosure Information