Reduced helper (OKT4+): suppressor (OKT8+) T ratios in aplastic anaemia: relation to immunosuppressive therapy

Decreased blood natural killer cell activity and immunoglobulin synthesis in vitro in aplastic anemia

Natural killer (NK) cell numbers and T lymphocyte subpopulations in peripheral blood were evaluated in six patients with aplastic anemia (AA). The immunophenotyping results were correlated to in vitro tests of NK cell cytotoxicity against K562 cells and of immunoglobulin (Ig) production after pokeweed mitogen (PWM) stimulation. A significant decrease was found both in the percentage of Leu 11 positive cells and in NK cell activity as compared to age- and sex-matched healthy controls. The decrease in NK cell activity could not be entirely compensated by an increase in effector/target cell ratios, thus suggesting not only a quantitative but also a functional defect in NK cells of the AA patients. Three of four AA patients tested showed no major increase of Ig production after PWM stimulation. All these three patients also had fewer "functional T helper" cells (Leu3+/Leu8-) and increased numbers of T suppressor/cytotoxic cells (Leu2+) when compared to controls. No significant differences in numbers of B lymphocytes (B1+) could be found. Our findings suggest a possible linkage between quantitative and qualitative abnormalities in lymphocyte subsets in aplastic anemia. However, no evidence was found to support the hypothesis of increased NK cell activation behind the hemopoietic depression in this disease.

Very severe aplastic anemia appearing after thymectomy

Aplastic anemia is a rare complication of thymoma and is extremely infrequent after thymectomy. We present a case of a 60-year-old woman with very severe aplastic anemia appearing sixteen months after thymectomy for a thymoma. She underwent thymectomy for a thymoma in April 2000. Preoperative examination revealed no hematologic abnormality. About sixteen months after the operation, she was readmitted because of pancytopenia with cough and fever. Bone marrow aspiration revealed a very severe hypoplasia in all the three cell lines with over 80% fatty tissue, and chest CT revealed no recurrence of thymoma. Her aplastic anemia had responded to cyclosporine A and granulocyte-colony stimulating factor (G-CSF).

Immune suppression therapy in aplastic anemia: influencing factors on response and survival

OBJECTIVES

Immune suppression (IS) therapy has provided another opportunity of cure or improvement in the aplastic anemia patients who cannot receive bone marrow transplantation due to many causes. There are a few reports regarding the factors that affect response, survival and prognosis after IS therapy, including antilymphocyte globulin (ALG) in aplastic anemia. Therefore, we analysed our experience to determine the prognostic factors.

METHODS

Statistically analysed were 172 patients, from April 1982 to July 1992, who were diagnosed as severe aplastic anemia and treated with IS therapy, including ALG, at Catholic University Medical College, St. Mary's Hospital.

RESULTS

Among 172 severe aplastic anemia (SAA) patients who entered the study from April 1982 to July 1992, 144 patients were analysed for response and 122 patient for survival. 58.4% (84/144) responded after the first course of IS therapy. Among those who did not respond on the first course an additional 44% (11/25) responded after the second course of IS therapy. Prognostic factors that might affect the response to the treatment and survival were analysed. In a univariate analysis of patients with no previous history of treatment before is therapy, and a shorter interval between diagnosis and treatment, higher hemoglobin levels before IS therapy, and higher granulocyte counts and combined use use of cyclosporin A(CSA) were positively associated with response (p < 0.05). The combined use of CSA during IS therapy, younger age, lower monthly requirement of platelets transfusion before IS therapy, higher leukocyte counts, higher percent of polymorphonuclear leukocytes, lower percent of lymphocyte, higher bone marrow cellularity and response were positively associated with survival (p < 0.05). In a multivariate analysis, shorter interval between diagnosis and treatment, no combined use of hemopoietic stimulants, such as androgen, and lesser total amount of transfusion were positively associated with Response (p < 0.05). Higher leukocyte counts before IS therapy and the combined use of CSA during IS therapy were significantly associated with longer survival (p < 0.05). Patients with complete or partial response had excellent prognosis (96.7%-100% of 5 year survival rates). In contrast, patients with no response after IS therapy had 45.1% of 5 year survival rates.

CONCLUSIONS

With these results from the retrospective study of IS therapy, we find many valuable factors that have an influence on response or survival. IS therapy improves the survival of responded patients with SAA, and we confirmed that IS therapy is an important therapeutic tool for the SAA patients who are not feasible candidates for bone marrow transplantation.

Identification of activated T cells and the suppressor/inducer subset in patients suffering from severe aplastic anemia

In patients with severe aplastic anemia (SAA), lymphocyte subpopulations were examined for the presence of HLA-DR and 2H4 (suppressor/inducer subset) antigen-expressing cells by flow cytometric analysis. Investigations were performed on peripheral blood lymphocytes before and after therapy with antithymocyte globulin (ATG) and methylprednisolone (MP), as well as on bone-marrow lymphocytes before therapy. Before treatment, only the absolute numbers of CD4+ T cells and the CD4+HLA-DR+/CD8+HLA-DR+ activated T cell ratio were significantly decreased (p less than 0.01 and p less than 0.001, respectively). Following successful ATG/MP treatment, a decrease in the CD4+/CD8+ T cell ratio was found. Regarding the suppressor/inducer subset, only absolute numbers of CD4+/2H4+ cells were somewhat higher in treated patients; the percentages were the same in all groups of patients. Studies performed on bone-marrow lymphocytes showed significantly decreased percentages of CD4+ and CD8+ T lymphocytes, which also express HLA-DR antigen. No significant changes in the distribution of activated T cells following ATG/MP therapy were found, suggesting that these cells play no major role in the pathogenesis of the disease.

Circulating activated suppressor T lymphocytes in hepatitis-associated aplastic anaemia

Lymphocyte subpopulations were measured in the blood of 21 children with severe aplastic anaemia (SAA). Five children with hepatitis-associated AA appeared to constitute a unique group. Compared with children with idiopathic AA, four of five children had a striking increase in percentage of activated suppressor T lymphocytes, which were defined by binding of both anti-Leu 2a and anti-HLA DR monoclonal antibodies (children with hepatitis-associated AA, 21.8 +/- 19.9% [mean +/- SD], children with idiopathic AA, 2.9 +/- 1.2%). However, there was no difference in the mean absolute number of the activated suppressor T lymphocytes between the two groups, because the mean number of lymphocytes was markedly less in children with hepatitis-associated AA (0.28 +/- 0.06 x 10(9)/l) than in those with idiopathic AA (1.64 +/- 0.74 x 10(9)/l). The mean helper: suppressor T lymphocyte ratio was significantly lower in children with hepatitis-associated AA (0.58 +/- 0.74) than in those with idiopathic AA (1.22 +/- 0.44). On the other hand, we did not find such a remarkable alteration of lymphocyte subpopulations in children with non-A non-B hepatitis who did not develop AA. These findings suggested that an imbalance of lymphocyte subpopulations and T lymphocyte activation may have pathogenetic relevance in some of the children with hepatitis-associated AA.

Immunomodulation therapy for severe aplastic anemia--ALG versus ALG plus cyclosporin A

Immunosuppressive treatment of aplastic anemia has been increasingly used as an alternative treatment to bone marrow transplantation. In this study, the additive effect of Cyclosporin A (CSA) (5mg/kg/day, at least 3 months) for maintenance of immunosuppression after antilymphocyte globulin (ALG) therapy (40mg/kg/day for 4 days) was compared to the previous ALG alone treatment (15mg/kg/day for 10 days). A high dose of methylprednisolone (20mg/kg/day for 5 days and 10mg/kg/day for 5 days) to the ALG group and a low dose of methylprednisolone (2mg/kg/day for 5 days) to the ALG plus CSA group were administered simultaneously. The results were as follows: 1) Sixteen (69.6%) out of twenty-three patients treated with ALG plus Cyclosporin A showed higher responses (CR: 48%, PR: 22%). On the contrary, nine out of nineteen in the ALG group showed lower responses (CR: 21%, PR: 26%). 2) Our data showed a tendency that male patients in age ranging from sixteen to thirty years showed an excellent response to ALG therapy (12/23: 52.2%). 3) The ALG plus CSA group revealed a faster response compared to the ALG alone group (15/16 within 6 months). 4) We speculate that ALG plus CSA therapy might be the treatment of choice for patients with a moderate degree of aplastic anemia. 5) Adding CSA to ALG increased the chance of infection, such as those with URI-like symptoms, but it did not affect the mortality rate. Our data suggest that the ALG plus CSA regimen may be a more useful therapeutic modality for patients with severe aplastic anemia who cannot be candidates for bone marrow transplantation and a randomized multicenter study is needed for confirmation of our preliminary study.

Does histologic grading of inflammation in bone marrow predict the response of aplastic anaemia patients to antithymocyte globulin therapy?

We tested the hypothesis of teVelde and Haak that the degree of bone marrow inflammation in aplastic anaemia might correlate with an immunological process responsive to immunosuppressive therapy. 120 patients with aplastic anaemia but no suitable marrow donor were treated with horse antithymocyte globulin (ATG) and 53 who had matched sibling donors with bone marrow transplants. Pretreatment bone marrow histology in methacrylate and paraffin specimens was graded by degree of inflammatory infiltrate in a four-tiered system. High grade (II-III) was compared to low (O-I) as a correlate of response to ATG. Complete and partial response to ATG was seen in 50% of patients with high grade marrow and 31% of patients with low grade marrow (P = 0.099). Only one of four patients with grade III inflammation responded significantly to ATG treatment. Median survival following ATG therapy was similar in both groups as well. There was a significantly lower median age in the patients with low grade (24.5 years) versus high grade (37.5 years) inflammation (P = 0.016). Grade also had no prognostic value in the marrow transplant group.

No evidence for gamma-interferon mediated haematopoietic inhibition by T cells in aplastic anaemia: an observation in the course of immunosuppressive therapy

Two patients with aplastic anaemia were treated with immunosuppressive agents and peripheral blood T cells were cryopreserved serially. Inhibitory activity of T cells to autologous CFU-E, gamma-IFN production by T cells and T cell subpopulations were assayed after remission. Inhibitory activity to autologous CFU-E was not correlated with the numbers or ratios of T cell subpopulations. gamma-IFN production by T cells were within the normal range when inhibitory activity was found. In addition, gamma-IFN production increased after haematopoietic recovery. These findings suggest that gamma-IFN is not a soluble mediator of T cell-mediated haematopoietic inhibition in aplastic anaemia.

Regulation of hematopoiesis by T lymphocytes and natural killer cells

T lymphocytes and natural killer (NK) cells exert both stimulatory and suppressive effects that regulate growth and differentiation of hematopoietic cells. Activated T and NK cells have been demonstrated in different pathological states of bone marrow failure and are proposed to play a role in the pathogenesis of the disease. T and NK cells have also been shown to be responsible for bone marrow graft rejection in both allogeneic and syngeneic donor/recipient combinations. Lymphocytes can regulate hematopoietic cell growth by direct cellular contact or by releasing soluble factors, such as colony-stimulating factors, immune interferon, lymphotoxin, and tumor necrosis factor, active on hematopoietic precursor cells.

Lymphocyte subsets in children with aplastic anemia

Twenty-four patients with aplastic anemia (AA) were evaluated with immunologic studies. Patients with posthepatitis AA had decreased proportions of T4 cells, increased proportions of T8 cells, and decreased T4:T8 ratios. Patients with constitutional AA had varied immunologic findings. There were no significant abnormalities in lymphocyte subsets in patients with idiopathic AA. Of the 12 patients who were treated with antithymocyte globulin (ATG), six (50%) responded. Nine of these patients are living 3-27 months after treatment; three of the nine are transfusion dependent. T-cell subsets were not helpful in predicting the response to ATG. Measurements of other immunologic mediators may be more useful with regard to pathophysiology and prognosis in AA.

Physical discrimination between human T-lymphocyte subpopulations by means of light scattering, revealing two populations of T8-positive cells

Light-scattering properties of human T-lymphocyte subpopulations selected by immunofluorescence were studied. Based on differences in orthogonal light scattering, two subpopulations of T8-positive cells can be distinguished. The first population (T8a) has the same orthogonal light-scattering properties as T4-positive cells, whereas the orthogonal light scattering of the second population (T8b) was about 70% larger. Orthogonal light scattering of Leu7-positive lymphocytes resembles that of the T8b population. We have studied the occurrence of the subpopulation in healthy individuals and we discuss their possible functional identification. Light-scattering properties of lymphocyte subpopulations in two patients with B-cell chronic lymphatic leukemia suggest that this observation is of clinical interest.

T-lymphocyte subpopulations in the peripheral blood and bone marrow of patients with aplastic anemia

A decrease in the absolute number of total lymphocytes, OKT3+ and OKT4+ lymphocytes, and a normal number of OKT8+ lymphocytes were found in the peripheral blood of patients with aplastic anemia. The OKT4:OKT8 ratio was decreased in patients due to a reduction in the percentage of OKT4+ cells and 3 out of 18 patients had a ratio less than 1. The values of the OKT4:OKT8 ratio were not associated either with the severity of the disease or with treatment with androgens. There was no correlation between the OKT4:OKT8 ratio and the number of transfusions received by patients. On the other hand, studies performed with bone marrow lymphocytes showed that the OKT4:OKT8 ratio for both patients and controls was lower than that of the peripheral blood. Since the ratio of OKT4:OKT8 cells in aplastic and control bone marrow was similar no direct pathogenic role can be assigned to the marrow for the imbalance detected in the peripheral blood.