Decreases in alpha beta T cell receptor negative T cells and CD8 cells, and an increase in CD4+ CD8+ cells in active Hashimoto's disease and subacute thyroiditis

Toenail and blood selenium mediated regulation of thyroid dysfunction through immune cells: a mediation Mendelian randomization analysis

Purpose

Specific nutrients found in food, such as minerals, antioxidants, and macronutrients, have a significant impact on immune function and human health. However, there is currently limited research exploring the relationship between specific nutrients, immune system function, and thyroid dysfunction commonly observed in autoimmune thyroid diseases, which manifest predominantly as hyperthyroidism or hypothyroidism. Therefore, the objective of this study was to investigate the connections between dietary traits and thyroid dysfunction, as well as the potential mediating role of immune cells, using Mendelian randomization (MR) analysis.

Methods

The two-step MR analysis used single-nucleotide polymorphisms as instruments, with a threshold of p < 5e-08 for nutrients and thyroid dysfunction, and p < 5e-06 for immune cells. Data from different GWAS databases and UK Biobank were combined to analyze 8 antioxidants and 7 minerals, while the data for 4 macronutrients came from a cohort of 235,000 individuals of European. The outcome data (hypothyroidism, N = 3340; hyperthyroidism, N = 1840; free thyroxin [FT4], N = 49,269; thyroid-stimulating hormone [TSH], N = 54,288) were source from the ThyroidOmics consortium. Immune trait data, including 731 immune phenotypes, were collected from the GWAS catalog.

Results

The results revealed that nutrient changes, such as lycopene, toenail and blood selenium, and α-tocopherol, impacted the immune system. Immune cells also affected thyroid function, with cDC cells promoting hypothyroidism and median fluorescence intensity (MFI) phenotypes correlating strongly with FT4 levels. Toenail and blood selenium reduce the relative cell counts (RCC) phenotypes of immune cells (CD62L- plasmacytoid DC %DC and transitional B cells %Lymphocyte), thereby diminishing its promoting effect on hypothyroidis. Furthermore, toenail and blood selenium mainly impacted phenotypes in three types of T cells (CD25 + ⁣ + CD8br, CD3 on CD45RA- CD4+, and CD45RA on Terminally Differentiated CD8br), reinforcing the negative regulation of FT4 levels.

Conclusion

The role of immune cells as mediators in the relationship between nutrients and thyroid dysfunction highlights their potential as diagnostic or therapeutic markers. Toenail and blood selenium levels can indirectly impact hypothyroidism by influencing the RCC levels of two types of immune cells, and can indirectly affect FT4 levels by influencing three types of T cells.

How Does Vitamin D Affect Immune Cells Crosstalk in Autoimmune Diseases?

Vitamin D is a secosteroid hormone that is highly involved in bone health. Mounting evidence revealed that, in addition to the regulation of mineral metabolism, vitamin D is implicated in cell proliferation and differentiation, vascular and muscular functions, and metabolic health. Since the discovery of vitamin D receptors in T cells, local production of active vitamin D was demonstrated in most immune cells, addressing the interest in the clinical implications of vitamin D status in immune surveillance against infections and autoimmune/inflammatory diseases. T cells, together with B cells, are seen as the main immune cells involved in autoimmune diseases; however, growing interest is currently focused on immune cells of the innate compartment, such as monocytes, macrophages, dendritic cells, and natural killer cells in the initiation phases of autoimmunity. Here we reviewed recent advances in the onset and regulation of Graves' and Hashimoto's thyroiditis, vitiligo, and multiple sclerosis in relation to the role of innate immune cells and their crosstalk with vitamin D and acquired immune cells.

Hepatitis C virus infection and thyroid autoimmune disorders: A model of interactions between the host and the environment

The hepatitis C virus (HCV) infection is an important public health problem and it is associated with hepatic and extrahepatic manifestations. Autoimmune thyroid diseases are common in HCV infected patients and the standard interferon-based treatment is associated with an increase of the immune-mediated thyroid damage. Recent evidence in the literature analyzed critical points of the mechanisms of thyroid damage, focusing on the balance between the two sides of the interaction: The environment (virus infection with potential cross-reaction) and the host (susceptibility genes with consistent immune response). The spectrum of antiviral treatment for chronic HCV infection is rapidly expanding for the development of dual o triple therapy. The availability of interferon-free combined treatment with direct antiviral agents for HCV is very promising, in order to ameliorate the patient compliance and to reduce the development of thyroid autoimmunity.

Immunoregulatory T cells, LFA-3 and HLA-DR in autoimmune thyroid diseases

AIM

The aim of the present study was to examine the changes in the expression of T-cell activation markers, namely CD4+ CD25+ and CD8+ in patients with AITD, namely Graves' disease and Hashimoto's thyroiditis as well as colloid nodular goitre. HLA-DR, LFA-3, and peripheral total lymphocytic count are also measured.

MATERIALS AND METHODS

We compared the expression of CD4, CD25, and CD8 surface markers in peripheral blood lymphocyte in Graves' disease and Hashimoto's thyroiditis as autoimmune thyroid diseases, as well as colloid goitre in comparison with healthy controls. Also, LFA-3 and HLA-DR were measured in the same groups using three-color flow cytometry. Total lymphocytic count in peripheral blood, thyroid function tests, antithyroid antibodies were also included in the laboratory investigations. The total number of participants was 65. All were recruited from endocrine clinics in a tertiary care hospital in the southern region of Saudi Arabia. All participants underwent history taking, clinical examination, laboratory workup, and radiological investigations. Neck ultrasound, technecium pertechnetate(ψψ) thyroid uptake, and fine-needle aspiration and cytology (FNAC) of the thyroid were done when indicated. The study was approved by the Hospital Research Isthics Committee and informed consents were obtained from all participants before enrollment in the study.

RESULTS

In comparison with thecontrol group, activation markers CD4, CD25, and CD8 were lower in the autoimmune thyroid diseases. Lymphocyte function antigen-3 (CD58) and total lymphocytic count were higher in the AIT diseases whereas HLA-DR was lower than that in the control group. The CD4/CD8 ratio was lower in the AITD compared with the healthy euthyroid subjects. No difference was found between patients with colloid nodular goitre and the healthy control in any of the study variables except for LFA-3 which was significantly higher in the colloid goitre group.

CONCLUSION

Our findings indicate downregulation of CD4+ CD25+ Treg as well as CD8+ T cells in autoimmune thyroid diseases. Downregulation of suppressor T lymphocytes helps initiation, progression, and maintenance of the autoimmune thyroid diseases. Lower HLA-DR and higher CD58 in AITDs indicate their role in the expression of the autoantigen and its escape from the immune surveillance. High levels of LFA-3 in colloid goitre indicate that the autoimmune process needs interacting factors, and not only the high level of LFA-3.

Immunological changes and increased expression of myxovirus resistance protein a in thyroid tissue of patients with recent onset and untreated Graves' disease

BACKGROUND

Few studies have systematically examined the immune cells that infiltrate thyroid tissue at the time of the onset of Graves' disease (GD). The role of viruses in the pathogenesis of autoimmune thyroid diseases is controversial. The present study analyzed inflammatory responses with respect to signs of virus infection.

METHODS

Thyroid tissue was obtained from 22 patients with newly diagnosed and untreated GD, 24 patients with chronic GD, and 24 controls. Inflammation was assessed by immunostaining for CD4+ and CD8+ T cells, plasma cells (CD138+), and plasmacytoid dendritic cells (PDCs). The production of interferon-inducible myxovirus resistance protein A (MxA) was analyzed as a sign of virus infection.

RESULTS

The degree of thyroid inflammation and fibrosis was significantly higher in both patient groups compared with that in controls. The number of CD4+ T cells and plasma cells (activated B cells) was significantly higher in both patient groups. CD8+ cells were only present in patients with chronic disease. MxA expression and the number of PDCs increased only in patients with newly diagnosed GD. There was a strong positive correlation between the number of PDCs and the number of MxA+ leucocytes.

CONCLUSION

The increase in CD8+ T cells during the chronic stage of GD suggests that they may play a role in progression of the autoimmune process from early to chronic thyroiditis. Upregulation of MxA expression during the early stages of the disease, and the positive correlation between the number of PDCs and the number of MxA+ leucocytes, suggests that activated PDCs secrete type I IFNs at the lesion site, possibly in response to viral infection.

Phenotypic and functional plasticity of gamma-delta (γδ) T cells in inflammation and tolerance

Gamma-delta T cells (γδ T cells) are an unique group of lymphocytes and play an important role in bridging the gap between innate and adaptive immune systems under homeostatic condition as well as during infection and inflammation. They are predominantly localized into the mucosal and epithelial sites, but also exist in other peripheral tissues and secondary lymphoid organs. γδ T cells can produce cytokines and chemokines to regulate the migration of other immune cells, can bring about lysis of infected or stressed cells by secreting granzymes, provide help to B cells and induce IgE production, can present antigen to conventional T cells, activate antigen presenting cells (APC) maturation, and are also known to produce growth factors that regulate the stromal cell function. γδ T cells spontaneously produce IFN-γ and IL-17 cytokines compared to delayed differentiation of Th1 and Th17 cells. In this review, we discussed the current knowledge about the mechanism of γδ T cell function including its mode of antigen recognition, and differentiation into various subsets of γδ T cells. We also explored how γδ T cells interact with different types of innate and adaptive immune cells, and how these interactions shape the immune response highlighting the plasticity and role of these cells-protective or pathogenic under inflammatory and tolerogenic conditions.

CD8+ T-Cell Deficiency, Epstein-Barr Virus Infection, Vitamin D Deficiency, and Steps to Autoimmunity: A Unifying Hypothesis

CD8+ T-cell deficiency is a feature of many chronic autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, dermatomyositis, primary biliary cirrhosis, primary sclerosing cholangitis, ulcerative colitis, Crohn's disease, psoriasis, vitiligo, bullous pemphigoid, alopecia areata, idiopathic dilated cardiomyopathy, type 1 diabetes mellitus, Graves' disease, Hashimoto's thyroiditis, myasthenia gravis, IgA nephropathy, membranous nephropathy, and pernicious anaemia. It also occurs in healthy blood relatives of patients with autoimmune diseases, suggesting it is genetically determined. Here it is proposed that this CD8+ T-cell deficiency underlies the development of chronic autoimmune diseases by impairing CD8+ T-cell control of Epstein-Barr virus (EBV) infection, with the result that EBV-infected autoreactive B cells accumulate in the target organ where they produce pathogenic autoantibodies and provide costimulatory survival signals to autoreactive T cells which would otherwise die in the target organ by activation-induced apoptosis. Autoimmunity is postulated to evolve in the following steps: (1) CD8+ T-cell deficiency, (2) primary EBV infection, (3) decreased CD8+ T-cell control of EBV, (4) increased EBV load and increased anti-EBV antibodies, (5) EBV infection in the target organ, (6) clonal expansion of EBV-infected autoreactive B cells in the target organ, (7) infiltration of autoreactive T cells into the target organ, and (8) development of ectopic lymphoid follicles in the target organ. It is also proposed that deprivation of sunlight and vitamin D at higher latitudes facilitates the development of autoimmune diseases by aggravating the CD8+ T-cell deficiency and thereby further impairing control of EBV. The hypothesis makes predictions which can be tested, including the prevention and successful treatment of chronic autoimmune diseases by controlling EBV infection.

Decrease of intrathyroidal CD161+Valpha24+Vbeta11+ NKT cells in Graves' disease

To clarify changes in the intrathyroidal natural killer T (NKT) cell subset, which prevents autoimmunity in patients with Graves' disease (GD), we examined intrathyroidal and peripheral lymphocytes in 11 patients with GD and peripheral lymphocytes in nine healthy volunteers using three-color flow cytometry. The proportion of CD161 (+) T cell receptor Valpha24 (+) Vbeta11 (+) cells, which represent the NKT cell subset, was lower in the thyroid of patients with GD than in the peripheral blood of the same patients and in the peripheral blood of healthy subjects. These results indicate that the proportion of intrathyroidal NKT cells is decreased in patients with GD and that this decrease may contribute to incomplete regulation of autoreactive T cells in GD.

Decrease of CD154 intensity on peripheral CD4+ T cells in autoimmune thyroid disease

To clarify immunological differences among patients with Graves' disease (GD) and Hashimoto's disease (HD) at various levels of severity, we examined the expression of the CD154 molecules on peripheral T cells, which regulate B cell activation, B cell differentiation, and T-cell survival. We found decreases in the intensities of CD154 on peripheral CD4(+) cells from euthyroid patients with GD and HD, but we did not find any differences between patients with different disease severities. CD8(+) cells did not express CD154 molecules. Thus, CD154 expression on CD4(+) cells may be related to the pathogenesis of the autoimmune thyroid diseases, not to the disease severity.

Relation of CD30 molecules on T-cell subsets to the severity of autoimmune thyroid disease

The prognosis of patients with autoimmune thyroid disease (AITD) varies. To clarify the immunologic differences among patients with various severities of AITD, we examined two types of molecules on peripheral T lymphocytes: CD195 (CCR5), which express dominantly on CD4(+) type 1 helper T (T(H)1) cells, and CD30, which is known as a marker of CD4(+) type 2 helper T (T(H)2) cells and a regulatory molecule of CD8(+) autoreactive cytotoxic T cells. We found presence of patients with high proportion (> 9%) of CD30 expression in CD4(+) cells in a group of patients with Graves' disease (GD) in remission compared to the patients with intractable GD and a decrease in the intensity of CD30 expression on CD8(+) cells from patients with severe Hashimoto's disease (HD) treated for hypothyroidism compared to patients with untreated and euthyroid HD. There was no difference in CD195 expression between these patients with GD or HD with different severities, but there was a decreased intensity of CD195(+) cells in thyrotoxic patients with GD. These results indicate that CD30 molecules on CD4(+) and CD8(+) cells may be related to the severities of GD and HD, respectively.

Independent involvement of CD8+ CD25+ cells and thyroid autoantibodies in disease severity of Hashimoto's disease

Hashimoto's disease (HD) is well known as an autoimmune thyroid disease caused by the destruction of the thyroid follicles, and can be diagnosed in the subclinical stage with thyroid-specific autoantibodies. However, some patients with HD develop hypothyroidism and are treated with thyroxine (severe HD), but most do not throughout their lives (mild HD). To clarify the immunologic differences between these two groups of patients with HD, we examined serum thyroid autoantibodies (antithyroid peroxidase antibodies and antithyroglobulin antibodies), CD4+ CD25+ cells that contain regulatory T cells and activated helper T cells, and CD8+ CD25+ cells that are activated cytotoxic T cells. There was no significant difference in CD4+ CD25+ cells between these HD groups, although the proportion of CD25+ cells within CD4+ cells increased in both groups as compared to normal controls. The serum titers of the thyroid autoantibodies and the proportion of CD25+ cells within CD8+ cells were higher in patients with severe HD than in those with mild HD. There was no correlation between these two parameters, and a two-dimensional analysis with these parameters differentiated these two groups of patients with HD more clearly. These results indicate that both thyroid autoantibodies and CD8+ CD25+ cells are independently involved in the disease severity of HD and CD4+ CD25+ cells are not related to the severity of HD.

Usefulness of surface phenotype study of intrathyroidal lymphocytes obtained by fine needle aspiration cytology in autoimmune thyroid disease and malignant lymphoma of the thyroid

OBJECTIVES

The surface phenotypes of intrathyroidal lymphocytes have been studied in various thyroid diseases. In most of the previous reports, intrathyroidal lymphocytes were obtained by surgical operation. We evaluated the usefulness of surface phenotype study of intrathyroidal lymphocytes obtained by fine needle aspiration in the diagnosis of Graves' disease, chronic thyroiditis, and malignant lymphoma of the thyroid.

PATIENTS AND DESIGN

Eighty-seven untreated patients including 24 with Graves' disease, 59 with chronic thyroiditis, and 4 with malignant lymphoma of the thyroid, and 2 treated patients with malignant lymphoma of the thyroid were studied. Surface phenotypes of the peripheral lymphocytes and the intrathyroidal lymphocytes obtained by fine needle aspiration were analyzed using a FACScan and the monoclonal antibodies: anti-Leu5b/CD2, Leu4/CD3, Leu3a/CD4, Leu2a/CD8, and Leu12/CD19. Percentages of cells positive for each monoclonal antibody were calculated. In one case with malignant lymphoma, monoclonal antibodies to surface-immunoglobulin markers were also studied.

RESULTS

In peripheral lymphocytes, the percentage of positive cells in each phenotype was almost normal in each disease. In intrathyroidal lymphocytes, the percentage of CD19 positive cells was increased, and the percentage of CD2 and CD3 positive cells was reduced compared to those of peripheral lymphocytes in each disease. The percentage of intrathyroidal CD19 positive cells was remarkably high in malignant lymphoma, constituting more than 70% of cells. In Graves' disease, a relative decrease in the percentage of intrathyroidal CD4 positive cells and an increase in CD8 positive cells compared to peripheral lymphocytes were observed. In 2 treated patients with malignant lymphoma of the thyroid, the intrathyroidal CD19 positive cells almost disappeared in a patient shortly after successful treatment, and reappeared to constitute 76% of cells in a patient in relapse. In one case with malignant lymphoma in which monoclonal antibodies to surface-immunoglobulin markers were studied, the clonality of the affected cells could be demonstrated; more than 70% of the cells were positive for kappa light-chain and mu and delta heavy-chain. This finding was proved by subsequent immunohistochemical study based on open biopsy.

CONCLUSIONS

Surface phenotype study of intrathyroid lymphocytes obtained by fine needle aspiration has limited utility in the evaluation or diagnosis of Graves' disease and chronic thyroiditis. However, this simple rapid method is very helpful in the diagnosis and follow up of malignant lymphoma of the thyroid.

Serial analysis of circulating T gamma/delta lymphocyte subpopulations in Graves' disease

In the present paper the distribution of peripheral blood T gamma/delta lymphocytes in Graves' disease patients is analyzed in order to correlate them with disease activity and with prognosis. Eighteen patients with Graves' disease, 24 patients with Hashimoto's thyroiditis and 32 sex- and age-matched healthy control subjects were studied. Peripheral blood CD3+ alpha/beta and gamma/delta T lymphocytes as well as CD4+ and CD8+ T cells, and CD19 (B) lymphocytes were analyzed by cytofluorometry. At diagnosis, patients who required a radical treatment for thyrotoxicosis control showed a significant decrease of T gamma/delta lymphocytes and an increase of B cells when compared with those who maintained the euthyroid state after methimazole. No correlation was detected between the percentages of these subpopulations and serum free thyroxine. This decreased proportion did not normalize after methimazole or radical treatments. These results suggest that the cytotoxic T gamma/delta compartment of the immune system is altered in patients with Graves' disease.

Opposite changes in serum soluble CD8 in patients at the active stages of Graves' and Hashimoto's diseases

Serum concentrations of soluble CD8 (sCD8) were examined by enzyme immunoassay in 154 patients with autoimmune thyroid diseases and 46 healthy controls. The numbers of peripheral CD8+ cells were also examined in the same subjects by flow cytometry. The serum concentrations of sCD8 were increased in patients with stimulative thyrotoxicosis caused by active Graves' disease, and decreased in patients with transient destructive thyrotoxicosis caused by the aggravation of Hashimoto's disease, and normal in euthyroid and hypothyroid patients with Graves' or Hashimoto's disease. The ratios of serum sCD8 levels to the numbers of CD8+ cells were increased in thyrotoxic patients with active Graves' disease, but not with active Hashimoto's disease, suggesting an increase in sCD8 production by CD8+ cells in active Graves' disease. The serum concentrations of sCD8 were correlated with the serum levels of thyrotropin receptor antibody (TRAb) and thyroid hormones in Graves' disease. These data indicate that serum sCD8 proteins change in opposite directions in the active stages of Graves' and Hashimoto's diseases, and may represent the disease activities.

131I dose-dependent thyroid autoimmune disorders in children living around Chernobyl

We assessed the major lymphocyte subsets in the peripheral blood, thyroid ultrasonography, levels of serum autoantibodies to thyroglobulin (AbTg), thyroid hormones, and thyroid-stimulating hormone (TSH) in 53 children without any chronic diseases living continuously around Chernobyl. The subjects ranged in age from 7 to 14 years and had different doses of 131I to their thyroid. Healthy children living on noncontaminated areas were assessed as controls. The majority of children with doses of 131I had normal levels of thyroid hormones. However, the percentages of positive sera for AbTg, TSH levels, ultrasonographic thyroid abnormalities, and abnormal echogenicity were significantly higher in children with doses of 131I than in controls. The dose of 131I to thyroid correlated positively with serum AbTg levels, percentage of CD3+CD4+ cells, and CD3+CD4+/CD3+CD8+ cell ratio and negatively with number of CD3+CD8+ and CD3-/CD16, CD56+ cells. Thus, our study demonstrates an association between dose of 131I and autoimmune thyroid disorders in this population of children.

Changes in T, B, and NK lymphocyte subsets during and after normal pregnancy

PROBLEM

Pregnancy affects the maternal immune system and the clinical course of maternal diseases. Here we report the changes in the detailed lymphocyte subsets of helper T cells, suppressor T cells, CD5+ B cells, T cell receptor (TCR) alpha beta-positive T cells (T alpha beta cells), TCR alpha beta-negative T cell (T gamma delta cells), and other during and after pregnancy through to one year postpartum, and discuss the significance of the changes.

METHOD

The absolute numbers of helper T cells, suppressor T cells, cytotoxic T cells, TCR alpha beta-negative T cells (T gamma delta cells), CD5- B cells, CD5+ B cells, and NK cell subsets were examined by two-color flow cytometry in peripheral blood from 51 healthy non-pregnant women, 106 healthy pregnant women, and 148 healthy postpartum women.

RESULTS

In early pregnancy, the numbers of suppressor T cells and NK cells with strong cytotoxicity (NK+3 cells) increased, and the number of cytotoxic T cells decreased. In late pregnancy, the helper T cell and NK+3 cell numbers decreased. T alpha beta, CD5- B and CD5+ B cells decreased during pregnancy. After delivery, helper T cells and cytotoxic T cells increased from 1 to 4 months postpartum, and suppressor T cells increased at 7 months postpartum. TCR alpha beta-negative T cells increased at 4 to 10 months postpartum. Both CD5- and CD5+ B cells decreased further at 1 month postpartum, but CD5+ B cells increased markedly at 7 to 10 months postpartum.

CONCLUSIONS

These data indicate that 1) early increases of suppressor T cells and NK+3 cells during pregnancy may be related to the mechanism to accept or reject the fetus in early pregnancy, respectively; 2) late decreases of helper T cells and NK+3 cells may be related to the maintenance of pregnancy: 3) postpartum increases of helper T cells, cytotoxic T cells, TCR alpha beta-negative T cells (T gamma delta cells), and CD5+ B cells may be related to the postpartum aggravation of autoimmune diseases; and 4) the immunological effects of pregnancy remains until about 1 year after delivery.

CD5 B cells in autoimmune and non immune-mediated thyroid dysfunctions

In a previous study we demonstrated a significant increase of CD5+ B subset in patients with Graves' disease (GD) compared with normal controls. The aim of this study was to compare the percentage of CD5+ B and CD5- B cells in GD with that in different forms of autoimmune and non immune-mediated thyroid diseases. Seventy-two patients were studied: 28 patients with GD, 20 with silent thyroiditis (ST), 12 with Hashimoto's disease (HD), and 12 subjects affected by hyperthyroidism due to toxic adenoma (TA). Eleven out of 28 patients with GD were also evaluated after six months of methimazole treatment. The study was performed by cytometric analysis. In GD the percentage and the absolute number of CD5+ B cells were significantly increased compared with normal controls (42.5 +/- 18.2% versus 19 +/- 6.3%, p < 0.0001; 142 +/- 153.3/cmm versus 46.9 +/- 22/cmm, p < 0.003, respectively. CD5+ B cells tended to normalise after six months of treatment. In ST the percentage of CD5+ B cells was increased (28.6 +/- 10.2%); conversely the absolute number was in the normal range. Patients affected by HD did not show any significant modification in B cells and their subsets in comparison with controls. In TA, CD5+ B were 7.6 /- 4.4% and 14.3 /- 10.9/cmm. Our results demonstrated a marked increase in both percentage and absolute number of CD5+ cells, only in active GD. The expansion of CD5+ B cells could play a role in the immune imbalance present in this disease.

The CD5+ B cells and myasthenia gravis

A high frequency of CD5+ B lymphocytes in the peripheral blood of patients with myasthenia gravis (MG) has been reported recently. These results seem to indicate an attractive linkage between CD5+ B lymphocytes and autoantibodies against Acetylcholine receptor in MG. We examined the frequency of CD5+ B cells in 20 patients with MG and 21 normal healthy controls by two-color flow cytometry. However, there were no significant differences in the percentages of CD5+ B lymphocytes between the two groups. We also examined the frequency of CD5+ B lymphocytes in the resected thymus of patients. The frequency of CD5+ B lymphocytes in the thymus was low and similar pattern to that in the peripheral blood. We checked the antibody (Ab) production against the human acetylcholine receptor in either CD5+ B or CD5- B lymphocytes using B lymphoblastoid cell line generated from the lymphocytes of 11 patients with anti-AChR Abs in the sera. Abs against the AChR in the human were mostly produced by CD5- B, not CD5+ B lymphocytes. The anti-AChR Abs (IgG) production of CD5+ B cells and CD5- B cells (mean +/- SD) were 6.8 +/- 2.4 fmol/ml and 18.5 +/- 17.6 fmol/ml, respectively. These results suggest that in MG, the frequencies of the CD5+ B lymphocytes in PBL may be genetic background and that there may be no strong linages between AChR Ab production and CD5+ B lymphocytes.

An in vitro model for the expansion of V gamma 9 delta 2 T lymphocytes during development

The gamma/delta T lymphocytes represent a minority of T lymphocytes in human peripheral blood. Although there have been reports of reactivity against (myco-) bacterial antigens and heat shock proteins, their function and antigen specificity remain ill defined. The biological role of gamma/delta T cells has been related to functions within the 'first line of defense'. Similar to gamma/delta T lymphocytes in the T-cell compartment, CD5 positive B cells represent a small subset of B lymphocytes, which is thought to be involved in the maintenance of natural immunity and autoimmunity. We provide evidence for the cooperation of gamma/delta T cells and CD5 positive B cells in the proliferative response of gamma/delta T cells to bacterial antigens. Our data indicate a strong proliferation of V gamma 9 delta 2 T cells in response to gram-negative bacteria, which is dependent upon the presence of CD5 positive B-CLL or activated normal B lymphocytes. The selective stimulation of the V gamma 9 delta 2 subpopulation by gram-negative bacteria is also confirmed by analysis of different gamma/delta T-cell clones. The interaction of gamma/delta T cells with activated B cells and gram-negative bacteria may prove to be a useful model similar to the expansion of the V gamma 9 delta 2 subpopulation during development. In addition, our in vitro system should provide new insights in the interaction of CLL B cells with the immune system and the antigens recognized by gamma/delta T cells.

Intrathyroidal lymphocyte subsets, including unusual CD4+ CD8+ cells and CD3loTCR alpha beta lo/-CD4-CD8- cells, in autoimmune thyroid disease

Intrathyroidal lymphocyte subsets were analysed in 13 euthyroid patients with autoimmune thyroid disease by two-colour flow cytometry and compared with subsets in peripheral blood. In both Graves' and Hashimoto's diseases, proportions of intrathyroidal CD5- B cells were higher than in peripheral blood. The numbers of such cells were correlated with serum levels of anti-thyroid microsomal antibodies. Proportions of T cells bearing alpha beta chains of T cell receptors (TCR alpha beta+ T; T alpha beta) and CD16+CD57+ natural killer (NK) cells were lower in the thyroid, but proportions of CD3hiTCR alpha beta-TCR gamma delta+ (T gamma delta) cells were not different. Proportions of CD4+Leu-8- helper T cells and CD4+CD57+ germinal centre T cells were higher and proportions of CD4+Leu-8+ suppressor-inducer T cells and CD8+CD57+ or CD8+CD11b+ suppressor T cells were lower than in the blood in both diseases. Proportions of CD5+ B cells were high in Graves' disease, and proportions of CD8+CD11b- cytotoxic T cells were high in Hashimoto's disease. Unexpectedly, CD4+CD8+ cells and CD3loTCR alpha beta lo/-CD4-CD8- cells were present in thyroid tissues of both diseases. These findings suggest that: (i) an imbalance in the numbers of regulatory T cells and of NK cells that had appeared in the thyroid resulted in the proliferation of CD5- B cells, which were related to thyroid autoantibody production; (ii) CD5+ B cells and cytotoxic T cells are important for the different pathological features in Graves' and Hashimoto's diseases, respectively; and (iii) intrathyroidal CD4+CD8+ cells and CD3loTCR alpha beta lo/-CD4-CD8- cells may be related to the pathogenesis of autoimmune thyroid disease.

Autoimmunity and selected environmental factors of disease induction

Autoimmune diseases may be induced by physical and/or chemical environmental factors. A review of the available literature on mercuric chloride, iodine, silicone, anilides, L-tryptophan, vinyl chloride, and canavanine suggests three general mechanisms by which they may induce disease. First, oxidative damage probably is a frequent process involved in disease induction and pathogenesis. Second, certain compounds also may generate antigen-specific immune responses that could then cross-react with self-tissues. Other xenobiotics might bind to self-tissues and increase self-tissue immunogenicity. Third, physical and chemical agents may also modulate the immune system. Finally, in response to controversies surrounding the influence of human activities on global climate changes, the immunosuppressive effects of ozone and ultraviolet radiation are discussed.

Chinese medicine, Coix seeds increase peripheral cytotoxic T and NK cells

Coix seeds, a Chinese medicine have been used in Japan and reported to be effective in patients with verruca vulgaris and verrucae planae juveniles. We investigated the in vivo effects on lymphocyte subsets in seven healthy volunteers who took six tablets of Coix seeds three times a day (a typical dose) for four weeks. Leukocyte counts and the percentage of total lymphocytes did not change but the percentages of CD3+CD56+ cells and CD16+CD57- cells increased significantly. These results indicate that Coix seeds increase peripheral cytotoxic lymphocytes and may be effective to viral infection through the enhancement of cytotoxic activity.