Patients with out-of-hospital cardiac arrest show decreased human leucocyte antigen-DR expression on monocytes and B and T lymphocytes after return of spontaneous circulation.

Immune disorders are an important feature of patients with out-of-hospital cardiac arrest (OHCA) after return of spontaneous circulation (ROSC). However, the precise immune alterations in patients with OHCA that occur immediately after ROSC are unclear. In this study, we investigated human leucocyte antigen-DR (HLA-DR) expression on circulatory monocytes and B and T lymphocytes. Sixty-eight consecutive patients with OHCA with ROSC >12 hours were enrolled. Clinical data and 28-day survival were recorded. Peripheral blood samples after ROSC days 1 and 3 were analysed to evaluate HLA-DR expression. Fifty healthy individuals were enrolled as controls. Compared with levels in healthy individuals, HLA-DR expression on monocytes and B lymphocytes, but not on T lymphocytes, decreased on days 1 and 3 after ROSC. No significant difference in HLA-DR expression was detected between survivors and non-survivors on day 1. For 41 patients with expression data for days 1 and 3, HLA-DR expression on monocytes and B lymphocytes in non-survivors was lower than that in survivors on day 3. In non-survivors, the mean fluorescence intensities of HLA-DR on B lymphocytes and percentages of HLA-DR+ T lymphocytes were lower on day 3 than on day 1. On days 1 and 3, there were significant correlations between HLA-DR expression on monocytes and B lymphocytes and clinical indicators, such as time to ROSC, adrenaline dose, acute physiology, chronic health evaluation II and the sequential organ failure assessment. The decreases in HLA-DR expression on circulatory monocytes and B and T lymphocytes after ROSC may be involved in the observed immunosuppression in patients with OHCA.