High Percentage of Regulatory T Cells before and after Vitamin B<sub>12</sub> Treatment in Patients with Pernicious Anemia

Abstract

<b><i>Introduction:</i></b> In some previous studies, vitamin B<sub>12</sub> treatment showed immunomodulatory effects and restored the immunological abnormalities in patients with pernicious anemia (PA). In the present study, peripheral blood T cell subsets, including regulatory T cells (T<sub>reg</sub>s), were examined before and after vitamin B<sub>12</sub> treatment in PA patients. <b><i>Patients and Methods:</i></b> The percentages of CD4, CD8, Th1, Th2 and T<sub>reg</sub>s were examined in 23 PA patients before vitamin B<sub>12</sub> treatment, in 23 other PA patients after vitamin B<sub>12</sub> treatment and in 28 healthy controls. <b><i>Results: </i></b>The mean percentage of CD8+ T cells was significantly higher in the control group (23.0%; 95% CI, 20.4-25.6%) than in the pre- (16.0%; 95% CI, 12.1-20.0%) and posttreatment groups (15.2%; 95% CI, 11.8-18.6%; p < 0.05). The CD4/CD8 ratio was significantly lower in the control group (2.01; 95% CI, 1.66-2.34) than in the pre- (3.45; 95% CI, 2.55-7.80) and posttreatment groups (2.97; 95% CI, 2.22-3.72; p < 0.05). There was no significant difference in the mean Th1/Th2 ratio among these groups. There were significant increases in the mean percentage of T<sub>reg</sub>s in the pre- (6.29%; 95% CI, 5.04-7.54%) and posttreatment groups (7.77%; 95% CI, 6.34-9.20%) compared with the control group (4.18%; 95% CI, 3.92-4.47%; p < 0.05). <b><i>Conclusions:</i></b> The percentage of T<sub>reg</sub>s was significantly higher in PA patients than in normal subjects, and this high T<sub>reg</sub> percentage was not different before and after vitamin B<sub>12</sub> treatment. Other immunological alterations also did not recover after vitamin B<sub>12</sub> treatment, so that these immunological changes appear to be the cause of PA and are not induced by vitamin B<sub>12</sub> deficiency.