Lymphocyte subpopulations in patients with hydroxocobalamin responsive megaloblastic anaemia

High percentage of regulatory T cells before and after vitamin B12 treatment in patients with pernicious anemia

INTRODUCTION

In some previous studies, vitamin B12 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(reg)s), were examined before and after vitamin B12 treatment in PA patients.

PATIENTS AND METHODS

The percentages of CD4, CD8, Th1, Th2 and T(reg)s were examined in 23 PA patients before vitamin B12 treatment, in 23 other PA patients after vitamin B12 treatment and in 28 healthy controls.

RESULTS

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(reg)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).

CONCLUSIONS

The percentage of T(reg)s was significantly higher in PA patients than in normal subjects, and this high T(reg) percentage was not different before and after vitamin B12 treatment. Other immunological alterations also did not recover after vitamin B12 treatment, so that these immunological changes appear to be the cause of PA and are not induced by vitamin B12 deficiency.

Effects of cyanocobalamin on immunity in patients with pernicious anemia

OBJECTIVE

The aim of the study was to evaluate the role of vitamin B(12) in patients with pernicious anemia.

MATERIALS AND METHODS

This study was conducted prospectively at the Turgut Ozal Medical Center, Department of Hematology, between April and November 2002. Absolute numbers and ratio of the surface antigens of T and B lymphocyte subgroups, CD4/CD8 ratio were calculated in order to evaluate changes in leukocyte and lymphocyte numbers; natural killer (NK) cell count, serum C3, C4, and levels of immunoglobulins G, A, and M were also measured to evaluate vitamin B(12) effect on immunity. Values obtained before treatment with cyanocobalamin were compared with those found during peak reticulocyte count.

RESULTS

In vitamin B(12)-deficient patients, absolute numbers of CD4+ and especially CD8+ lymphocytes were found to be decreased; CD4/CD8 ratio increased, and NK cell activity was depressed. After cyanocobalamin treatment, absolute numbers and percentage of lymphocyte subgroups were elevated. Increased CD4/CD8 ratio and depressed NK cell activity were restored and levels of C3, C4, and immunoglobulins were elevated.

CONCLUSION

These findings suggest that vitamin B(12) has important immunomodulatory effects on cellular immunity, and abnormalities in the immune system in pernicious anemia are restored by vitamin B(12) replacement therapy.

The pathological examinations of gastric mucosa in patients with Helicobacter pylori-positive and -negative pernicious anemia

BACKGROUND

The basic histopathological finding in gastric mucosa is chronic atrophic gastritis in patients with pernicious anemia.

MATERIALS AND METHODS

We evaluated the frequency of Helicobacter pylori and pathological examinations of gastric mucosa in pernicious anemia (n = 30) by endoscopical findings and biopsy. The results were compared with gastric mucosa specimens of patients with H. pylori-positive nonulcer dyspepsia (n = 36) and H. pylori-negative nonulcer dyspepsia (n = 21).

RESULTS

H. pylori was diagnosed in 12 patients (40%) with pernicious anemia. Fundal biopsy examinations showed atrophic gastritis in 30 patients (100%), intestinal metaplasia in 13 patients (43.3%), lymphoid follicle in 15 patients (50%), and dysplasia in 6 patients (20%). Antral biopsy examinations showed atrophic gastritis in 8 patients (26.6%), intestinal metaplasia in 8 patients (26.6%), lymphoid follicle in 8 patients (26.6%), and dysplasia in 3 patients (10%). The frequency of fundal inflammation, atrophy, intestinal metaplasia, lymphoid follicle, and dysplasia and antral intestinal metaplasia and mild antral dysplasia were found to be higher in those in the pernicious anemia group than in the nonulcer dyspeptic patients. Antral inflammation, atrophy, and moderate and severe antral dysplasia were found to be higher in those in the nonulcer dyspeptic group.

CONCLUSIONS

Particularly, fundal precancerous lesions were found to be more frequent in patients with pernicious anemia independent of H. pylori.

Immunomodulation by vitamin B12: augmentation of CD8+ T lymphocytes and natural killer (NK) cell activity in vitamin B12-deficient patients by methyl-B12 treatment

It has been suggested that vitamin B12 (vit.B12) plays an important role in immune system regulation, but the details are still obscure. In order to examine the action of vit.B12 on cells of the human immune system, lymphocyte subpopulations and NK cell activity were evaluated in 11 patients with vit.B12 deficiency anaemia and in 13 control subjects. Decreases in the number of lymphocytes and CD8+ cells and in the proportion of CD4+ cells, an abnormally high CD4/CD8 ratio, and suppressed NK cell activity were noted in patients compared with control subjects. In all 11 patients and eight control subjects, these immune parameters were evaluated before and after methyl-B12 injection. The lymphocyte counts and number of CD8+ cells increased both in patients and in control subjects. The high CD4/CD8 ratio and suppressed NK cell activity were improved by methyl-B12 treatment. Augmentation of CD3-CD16+ cells occurred in patients after methyl-B12 treatment. In contrast, antibody-dependent cell-mediated cytotoxicity (ADCC) activity, lectin-stimulated lymphocyte blast formation, and serum levels of immunoglobulins were not changed by methyl-B12 treatment. These results indicate that vit.B12 might play an important role in cellular immunity, especially relativing to CD8+ cells and the NK cell system, which suggests effects on cytotoxic cells. We conclude that vit.B12 acts as an immunomodulator for cellular immunity.

Functional defect of T cells in autoimmune gastritis

The functional response and phenotypic characterisation of peripheral blood T cells were studied in 41 patients with autoimmune gastritis--nine patients with autoimmune gastritis alone, 11 with untreated pernicious anaemia, and 21 with resolved pernicious anaemia who were taking vitamin B-12. Phenotypic analysis showed no changes in the CD4/CD8 ratio in any group of patients. CD3+ cells were significantly decreased and CD16+ cells were significantly increased in patients with autoimmune gastritis alone. Phytohaemagglutinin induced T cell proliferation, with or without interleukin 2, was reduced in the three groups. T cell proliferation induced by phorbol myristate acetate was normal. Interleukin 2 production of phytohaemagglutinin-stimulated lymphocytes was normal in the three groups. Five patients with pernicious anaemia treated with vitamin B-12 were followed and persistent hypoproliferation of T cells in response to phytohaemagglutinin was observed. The follow up study of the phenotype of these patients showed a significant increase of the CD2+ CD3- lymphocyte population after six months' treatment. In conclusion, the three groups of autoimmune gastritis patients studied have a functional defect in T cells that is independent of B-12 treatment and of the presence of pernicious anaemia.

Pure red cell aplasia following pernicious anemia

A rare case of pure red cell aplasia (PRCA) in association with pernicious anemia is reported. A 40-year-old man presented with typical clinical and laboratory features of pernicious anemia and received intramuscular injections of vitamin B12, with satisfactory response. Anemia recurred 6 months later despite continued therapy, and the patient was noted to have PRCA, which was treated successfully with two courses of high-dose bolus methylprednisolone therapy. His peripheral mononuclear cells before the therapy suppressed colony formation of early erythroid precursors (BFU-E) from normal bone marrow; such a suppressive effect was not found after recovery from anemia.

Longitudinal study of circulating gastric antibodies in pernicious anaemia

Temporal changes in gastric antibody response were investigated in 113 (51 men, 62 women) patients with confirmed pernicious anaemia. Their ages ranged from 31-92 years (mean (SD 13.2) 66). At diagnosis, parietal cell antibody and intrinsic factor antibody were detected in 90.9% and 39.1% of all patients, respectively. When the tests were repeated after a mean follow up of 70 months (range 14-137), parietal cell antibody and intrinsic factor antibody were positive in 82.8% and 58.7%, respectively. There was a definite but not significant trend for the organ specific parietal cell antibody to disappear; intrinsic factor antibody became more positive. These results may indicate that with progressive parietal cell destruction, the antigen is no longer available to sustain an immunological response. On the other hand, this hypothesis does not explain the increased prevalence of intrinsic factor antibody which is also a product of parietal cells.

Lymphocyte surface phenotypes in pernicious anemia

Because an immunological defect of an unknown nature is thought to be a factor in the pathogenesis of pernicious anemia, we studied lymphocyte surface phenotypes in 40 patients and compared them with 113 healthy controls. The only significant difference that emerged was in their slightly decreased number and proportion of surface immunoglobulin (lambda chain) -bearing cells. Of specific interest, the numbers of OKT4+ and OKT8+ lymphocytes and the T4+/T8+ ratios were not significantly different from control values. A sizable minority of patients had increased ratios, while a smaller number had decreased values. No explanation or identifying feature was apparent for those patients with either increased or decreased T4+/T8+ ratios. (One patient with a very low ratio, who was excluded from our analysis, developed acquired immune deficiency syndrome.) No differences were apparent in T4+/T8+ ratios or any other lymphocyte surface phenotypic characteristics when patients were segregated by presence of anti-intrinsic factor antibody or anti-parietal cell antibody, or by race, sex, or age. Our results in a racially heterogeneous group of patients do not support the suggestion that T4+/T8+ ratios are usually abnormal in prenicious anemia or that the presence of anti-intrinsic factor antibody is associated with such abnormality.

Immunological aspects of gastritis and pernicious anaemia

Pernicious anaemia (PA) and chronic atrophic gastritis (CAG) aggregate in families, occur more often in women, and are associated with various heritable traits such as fair skin and blue eyes. They are linked to certain HLA types. Linkages are relatively weak for A and B antigens, but somewhat stronger in the case of DR antigens. There are strong associations between PA and other organ-specific autoimmune diseases, particularly those affecting the thyroid. Discordance for PA in monozygotic twins has been reported, and it may well be that expression of the disease requires, in a genetically susceptible individual, initial injury to the gastric mucosa by some environmental agent such as a virus or some physical irritant, with perpetuation of injury then depending upon autoimmune mechanisms. Numbers of T cells are substantially increased in the gastric mucosa of patients with PA, but the ratio of T suppressor to T helper cells is normal. There is a relatively greater increase in numbers of cells not of T lineage, presumably B-cells. Gastric autoantibodies, both to different components of the parietal cell and to two sites on the IF molecule, are present in a majority of patients with PA. There is evidence that these autoantibodies, especially PCA, may be cytotoxic to parietal cells, and may also inhibit their maturation and proliferation. Antibodies to chief cells have not been described, and the parallel disappearance of these cells in atrophic gastritis is unexplained. The peripheral blood lymphocytes of some patients with autoimmune gastritis transform, or produce lymphokines, when exposed to gastric antigens, and patients with PA have been shown to have delayed type cutaneous hypersensitivity to gastric antigens. The relevance of these observations to the pathogenesis of their gastric mucosal lesion is unclear. There is a growing body of evidence to support the operation of humoral immune mechanisms in autoimmune gastritis, but this clearly does not preclude the coexistent involvement of cellular mechanisms. For example, impaired suppressor T cell function has been strongly implicated in certain other autoimmune disorders, but has received scant attention in PA. By generally accepted criteria, PA is an excellent example of an organ-specific autoimmune disease. As yet, there is no acceptable single unifying hypothesis which will account for all of the phenomena which have been described in the disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Peripheral blood lymphocyte subpopulations in patients with primary proliferative and secondary polycythaemia

Peripheral blood lymphocyte subpopulations were measured in 18 patients with primary proliferative polycythaemia and 13 patients with secondary polycythaemia. A decrease in numbers of suppressor T lymphocytes and an increase in the helper:suppressor T lymphocyte ratio was found in those with primary polycythaemia compared with normal subjects and patients with secondary polycythaemia. If other causes of an increased helper:suppressor ratio are excluded this variable may be useful in confirming the myeloproliferative nature of patients with erythrocytosis.

Restoration of decreased suppressor cells by vitamin B12 therapy in a patient with pernicious anemia

A unique case of pernicious anemia is described. Initially, the percentage of OKT8-positive blood cells was markedly decreased, resulting in an increase in the OKT4/OKT8 ratio. The level of OKT8-positive blood cells was, however, returned to normal after vitamin B12 therapy. The finding may propose a possible role of the imbalance of blood lymphocyte subpopulations on the pathogenesis of pernicious anemia and also a responsibility of vitamin B12 for such a selective reduction in the OKT8-positive blood cells.

Lymphocyte subpopulations in megaloblastic anaemia due to vitamin B-12 deficiency

Lymphocyte subpopulations were measured in the blood of 17 patients with megaloblastic anaemia due to vitamin B-12 deficiency. 14 patients had pernicious anaemia and 3 others were gastrectomized. By using monoclonal antibodies recognizing T cell surface markers and immunofluorescence microscopy, we found a significant decrease in the number of circulating suppressor T cells and an increase in the ratio of helper to suppressor T lymphocytes in pernicious anaemia patients. This finding may be related to other immune abnormalities found in pernicious anaemia, e.g. the presence of multiple autoantibodies.