Features of peripheral CD8+CD57+ lymphocytes in patients with autoimmune hemolytic anemia

Autoimmune hemolytic anemia (AIHA) is an acquired condition characterized by the presence of autoantibodies recognizing erythrocyte-related antigens. Several components of the immune system are involved in disease pathogenesis. Among them, as for other autoimmune disorders, a role for specific CD8þCD57þ regulatory cells subset could be hypothesized. We evaluated this lymphocyte subset by flow cytometry in 18 AIHA patients randomly selected in a retrospective population of 29 cases. Secondary forms were observed in 65.5% of cases, whereas frequencies of warm, cold, mixed, and atypical forms were similar. Cold agglutinins and cryoglobulins tested positive in 44.8% and 10.3% of cases, respectively. These patients exhibited a higher frequency of peripheral vascular symptoms (odds ratio¼8.2, p¼.04) and complement consumption (odds ratio¼7.2, p¼.02). Frequency of CD8þCD57þ cells resulted significantly higher in AIHA patients than in control group (17.0 ± 15.8% vs 8.2 ± 5.0%, p¼.04). Regardless of therapeutic schedule, patients with partial or no response to therapy (8/18) showed higher frequencies of CD8þCD57þ cells as compared with controls (23.6 ± 21.3% vs 8.9± 4.9%, p¼.01), whereas 10/18 complete responders (CR) showed lower levels of CD8þCD57þ cells (11.7 ± 6.9%, p¼.11). CR and controls showed similar values (p¼.24). This study suggests that monitoring this lymphocyte subset before and after treatment administration might have a prognostic value. Moreover, CD8þCD57þ cells may represent a possible therapeutic target to restore the normal balance between lymphocyte populations.