Thymic endocrine activity in children with idiopathic growth-hormone deficiency

Experimental and clinical evidences suggest that thymic endocrine function is modulated by the neuroendocrine network and in particular by growth hormone. The plasma of thymulin has been found reduced in congenital hypopituitarism and increased in acromegalic conditions when compared with the values observed in age-matched controls. In the present paper we have investigated in congenital GH-deficient children the effect of one year therapy with GH on the plasma level of thymulin, IGF-1 and plasma zinc; this last parameter has been checked because zinc is required for thymulin activity and modulates IGF-1 production. The basal thymulin and IGF-1 values are lower in GH deficient children than age-matched controls whereas zinc levels show a slight reduction. GH therapy induces a significant increment both of thymulin and IGF-1 levels and a slight increase of plasma zinc. A positive correlation has been found between zinc values and thymulin activity but not between GH and thymulin. Whether the recovery of thymulin production in GH deficient children by GH therapy is mediated by IGF-1 or by bioavailability of zinc ions remains to be established.

Gross, histologic, cytochemical, and immunocytochemical study of medullary thyroid carcinoma in sixteen dogs

The gross, histomorphologic, cytochemical, and immunocytochemical findings in 16 dogs with medullary thyroid carcinoma were evaluated. Grossly, the neoplasms were encapsulated, firm, lobulated, and grey-white to tan. The typical histologic pattern was groups or sheets of round to polygonal cells with fibrovascular stroma, which was thickened and hyalinized in places. Variants of clear cell (two dogs), giant cell (one dog), and oxyphil cell (one dog) types were also seen. In all 16 dogs, Grimelius-stained sections of the neoplasms revealed intracytoplasmic silver granules; ten tumors contained amyloid and four contained mucin. Immunohistochemically, the neoplasms reacted to AE1/AE3 (n = 13), S-100 protein (n = 5), neuron specific enolase (n = 14), synaptophysin (n = 11), calcitonin (n = 16), somatostatin (n = 4), gastrin (n = 7), and serotonin (n = 6). Only one neoplasm was positive for vimentin. None of the neoplasms reacted to antibodies for neurofilaments, thyroglobulin, insulin, glucagon, or adrenocorticotrophic hormone. Eleven neoplasms contained multiple (two to four) peptides, in various combinations. It was concluded that in dogs, gross and histologic features can be used to distinguish medullary thyroid carcinoma from other thyroid malignancies. Cytochemical and immunocytochemical studies with neuron specific enolase, synaptophysin, and calcitonin can be used to establish the diagnosis of medullary thyroid carcinoma in dogs.

Administration of thyroxine in treated Graves' disease. Effects on the level of antibodies to thyroid-stimulating hormone receptors and on the risk of recurrence of hyperthyroidism

BACKGROUND

Antibodies to thyroid-stimulating hormone (TSH) receptors that stimulate the thyroid gland cause hyperthyroidism in patients with Graves' disease, and their production during antithyroid drug treatment is an important determinant of the course of the disease. One factor that might contribute to the persistent production of antibodies to TSH receptors is stimulation of the release of thyroid antigens by TSH during antithyroid drug therapy. We therefore studied the effect of the suppression of TSH secretion by thyroxine on the levels of antibodies to TSH receptors after thyroid hormone secretion had been normalized by methimazole.

METHODS AND RESULTS

The levels of antibodies to TSH receptors were measured during treatment with methimazole, either alone or in combination with thyroxine, in 109 patients with hyperthyroidism due to Graves' disease. The patients first received 30 mg of methimazole daily for six months. All were euthyroid after six months, and their mean (+/- SD) level of antibodies to TSH receptors decreased from 64 +/- 9 percent to 25 +/- 15 percent (P less than 0.01; normal, 2.9 +/- 1.4 percent). Sixty patients then received 100 micrograms of thyroxine and 10 mg of methimazole and 49 received placebo and 10 mg of methimazole daily for one year. In the thyroxine-treated group, the mean serum thyroxine concentration increased from 108 +/- 16 nmol per liter to 145 +/- 11 nmol per liter (P less than 0.01), and the level of antibodies to TSH receptors decreased from 28 +/- 10 percent to 10 +/- 3 percent after one month of combination therapy. In the patients who received placebo and methimazole, the mean serum thyroxine concentration decreased and the level of antibodies to TSH receptors did not change. Methimazole, but not thyroxine or placebo, was discontinued in each group 1 1/2 years after the beginning of treatment. The level of antibodies to TSH receptors further decreased (from 6.6 +/- 3.2 percent at the time methimazole was discontinued to 2.1 +/- 1.2 percent one year later) in the patients who continued to receive thyroxine, but it increased (from 9.1 +/- 4.8 percent to 17.3 +/- 5.8 percent during the same period) in the patients who received placebo. One patient in the thyroxine-treated group (1.7 percent) and 17 patients in the placebo group (34.7 percent) had recurrences of hyperthyroidism within three years after the discontinuation of methimazole.

CONCLUSIONS

The administration of thyroxine during antithyroid drug treatment decreases both the production of antibodies to TSH receptors and the frequency of recurrence of hyperthyroidism.

Neuroendocrine-immune interactions: a theoretical approach to aging

Among the systemic theories of aging, both a 'nervous-neuroendocrine' and an 'immune' hypothesis have been proposed. The discovery of the complex interactions working among the neuroendocrine and the immune systems suggests the revision of the systemic theories of aging, particularly in the light of the recent evidence that some age-associated alterations in the neuroendocrine and in the immune systems are mutually interdependent even at very old age, as revealed by the fact that experimental manipulation of one of the two systems modifies and sometimes restores the function of the other one. These findings clearly demonstrate that at least some of the age-related alterations of the nervous, neuroendocrine and immune networks are not per se intrinsic and irreversible and that the definition of the temporal priority in the age-related deterioration is rather is rather difficult to be assigned to one or other homeostatic apparatuses. As an alternative to pure, either 'neuroendocrine' or 'immune', theories of aging, it has been hypothesized that, due to the strict interactions existing among the nervous, neuroendocrine and immune systems during the whole life of the organism, it is the disruption of such interactions in old age which is responsible for most of the age-associated dysfunctions (Fabris, 1986). This theoretical approach is discussed in the light of a stochastic or single-cause oriented hypothesis of aging.

A new immunoradiometric assay (IRMA) system for thyroglobulin measurement in the follow-up of thyroid cancer patients

A new commercially available kit for thyroglobulin (Tg) measurement [immunoradiometric assay (IRMA) system based on monoclonal antibodies] was used in 479 patients with thyroid carcinoma. The effective working range was 1 ng/ml, and results were strongly correlated with our homemade radioimmunoassay (RIA). This IRMA method is less susceptible to interferences of auto-antibodies than our RIA. During thyroxine (T4) treatment, the Tg level was undetectable in 98% of patients after total thyroid ablation, in 91% after total thyroidectomy and in 42% after lobectomy only. In this situation, Tg was found in all patients with large metastases and in 88% of those with small metastases. Following T4 withdrawal, Tg was detectable in all patients with neoplastic disease and in 13% of those in complete remission after total thyroid ablation. In conclusion, Tg measured with this IRMA method appears to be a reliable marker of differentiated thyroid carcinoma.

Influence of stress on the maturity of T-cells

Stress is known to influence the immune function via an effect on the central nervous system. We previously presented data showing that stress alters the population of T-cell subsets in mice. The variations of T-cell subsets in the thymus, peripheral blood, and spleen in mice similarly stressed by immobilization or by unavoidable and opioid-dependent stress were measured by flow cytometry using the monoclonal antibodies anti-L3T4, anti-Lyt 1, anti-Lyt 2 and anti-Thy 1, 2. Immobilization stress was applied for three days and T-cell subsets were measured on the days 1, 2 and 3, as well as on day 7 after release from immobilization. Lyt 2-positive cells in the thymus were the most sensitive to stress, showing significant variations. The proportion of immature T-cells increased in the thymus, blood and spleen of the stressed mice. When diazepam or naloxone were administered 30 min before the initiation of stress, these variations tended to decrease. Thus, the ratio of T-cell subsets varied with the duration of immobilization stress. This appeared to be partly mediated by the opioid system and the central nervous system.

Herpes simplex virus hepatitis in pregnancy. Two patients successfully treated with acyclovir

Two cases of herpes simplex virus hepatitis in pregnancy are presented. Each case was characterized by extremely high serum aminotransferase levels with minimal bilirubin elevation. In both cases, liver biopsy was instrumental in arriving at the diagnosis. In addition, computed tomography showed a radiographic appearance of the liver not characteristically seen in other hepatic disorders of pregnancy. A high index of suspicion in the second case led to early recognition and treatment. Despite the presence of fulminant liver failure and evidence of herpes encephalitis in the other case, institution of therapy with acyclovir was associated with complete recovery in both patients. The present cases are compared and contrasted with the literature. The incidence of two cases within a 6-month period suggests that herpes simplex virus hepatitis in pregnancy may occur more frequently than previously reported.

Effects of neonatal sexual differentiation, growth hormone and testosterone on thymic weights and thymosin-beta 4 in hypophysectomized rats

Experiments were conducted to analyze the effects of growth hormone and testosterone in conjunction with the effects of neonatal sexual differentiation (via castration of males at days 2 or 11 of age and androgenization of females at day 3 of age) on thymic weight and thymosin-beta 4 concentrations in hypophysectomized rats (day 30 of age). Ten days post-hypophysectomy, hormonal treatments were initiated on males, male castrates, females, and androgenized females. Growth hormone (25 micrograms daily), testosterone propionate (100 micrograms/day), and the combination of the two hormonal treatments were administered for seven days, then thymic weights and blood samples were collected. Administration of growth hormone to hypophysectomized rats increased thymosin-beta 4 concentration in a dose-dependent manner, but injection of testosterone had no effect on thymosin-beta 4 concentrations. Testosterone treatment decreased thymic weights whereas growth hormone increased thymic weights. Hypophysectomized males had increased thymosin-beta 4 concentrations compared with female and neonatally-androgenized female rats. However, hypophysectomy eliminated any thymic weight differences between males and females. The data support a possible endocrine role for the thymus gland and thymic peptides in that they are integrated into the control and support of other endocrine systems. Although differences in thymosin-beta 4 concentrations were noted between males and females, sexual differentiation of the immune system was unaltered by neonatal castration of males or testosterone treatment of females and may indicate sexual differences in immune function are established in utero.

Effective laboratory evaluation of thyroid status

This article focuses on recent developments in thyroid-related laboratory tests, including analytical methods, clinical utility, and limitations of TSH, FT4, T4, FT3/T3, thyroglobulin, and thyroid autoantibodies and the effective use of these tests in the diagnosis of various forms of hypothyroidism or hyperthyroidism, and the management of patients undergoing T4 replacement, T4 suppression, or antithyroid drug therapy.

Euthyroid low thyroxine (T4) and triiodothyronine (T3) states in prematures and sick neonates

This article reviews the ontogenesis of thyroid system function in the human fetus and newborn and characterizes thyroid function in the premature infant. Thyroid function disorders associated with neonatal adaptation and illness also are reviewed; these include transient hypothyroxinemia, transient primary hypothyroidism, and the syndrome of nonthyroidal illness.

Neonatal hepatitis and lymphocyte sensitization by placental transfer of propylthiouracil

A female newborn whose mother was taking propylthiouracil (PTU) for Graves' disease, presented with transient thyrotoxicosis (serum triiodothyronine 1,710 ng/dl) and signs of acute hepatic injury. Jaundice and choluria were evident on her fourth day of life. Serum total bilirubin reached 14 mg/dl, with a direct fraction of 11 mg/dl. Serum alanine aminotransferase and aspartate aminotransferase showed moderate elevations (110 IU/l and 61.5 IU/l, respectively), as well as the alkaline phosphatase which increased to about twice the upper limit of normal. When incubated with PTU, the patient's cultured peripheral lymphocytes underwent transformation to more than twice the values found in 2 controls, with a stimulation index (SI) of 3.19, compared to SI of 1.45 and 1.15 for the controls, suggesting a hypersensitivity mechanism involved in the hepatic injury. Although about 20 cases of PTU induced hepatic damage were reported in the medical literature, this is, as far as we know, the first description of neonatal liver injury probably caused by placental transfer of this drug.

Influence of pregnancy on human immunodeficiency virus disease

Over a period of 3 years (mean 16, extremes 3 and 36 months), we compared clinical and laboratory parameters of 128 female, human immunodeficiency virus (HIV)-infected patients, all in clinical stage II or III (CDC classification). 34 patients were pregnant and delivered a viable infant after at least 28 weeks of amenorrhea (group I), 29 patients were pregnant and had a spontaneous or induced abortion during the first or second trimester (group II), and 64 were non-pregnant female control patients (group III). The changes in the clinical stages over time were not statistically significant between the groups. The only laboratory parameters that were significantly higher in group I at the time of the delivery were: leucocyte count (p less than 0.001), lymphocyte count (p less than 0.05), and sedimentation rate (p less than 0.001). These changes are known to be related to pregnancy and not to HIV disease. All other laboratory parameters showed no significant differences within and between the groups. We conclude, that pregnancy--carried to term or interrupted--does not aggravate the natural evolution of HIV infection in clinical stage II and III patients.

Lymphocyte subsets in the blood: a diagnostic window on the lymphoid system?

The assessment of peripheral blood lymphocyte numbers and ratios has been performed in almost every conceivable disease state, but do these values give any useful information about immune status? Jürgen Westermann and Reinhard Pabst try to answer this question and to put peripheral blood population assessments into the whole-body context.

Usefulness of the combined antithyroglobulin antibodies and thyroglobulin assay in the follow-up of patients with differentiated thyroid cancer

A total of 1050 patients with differentiated thyroid cancer (DTC) have been followed in the Thyroid Center of Padua by means of serum thyroglobulin (Tg) measured with IRMA method and anti-Tg antibodies (TgAb) assays. Circulating TgAbs were detected in 102 (9.7%) patients. In 32 of these 102, TgAbs were evaluated before and after total thyroidectomy and 131I ablation. In these patients no relationship was found between preoperative serum TgAb levels on the one hand and tumor stage at diagnosis or outcome of the disease on the other. During the follow-up, TgAb serum levels decreased or disappeared in 21 cases considered tumor-free, while they remained unchanged or even increased, in comparison with the preoperative ones, in 11 patients, 5 with proven metastases and 6 considered tumor-free. Evaluating the whole group of 102 TgAb-positive patients, we observed that TgAb serum levels, measured after thyroid ablation, were significantly higher in cases with metastases than in those considered tumor-free (653.0 +/- 196.9 vs 157.7 +/- 116.5 U/ml, m +/- SD, p less than 0.0001). In the group of patients with metastases and circulating TgAbs, Tg serum levels were elevated in 27% of cases on TSH-suppressive therapy and in 44% off therapy when nodal metastases were present, and in 67% of cases on TSH-suppressive therapy and in 83% off therapy when distant metastases were present.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical localization and identification of members of the pancreatic polypeptide (PP)-fold family in human thyroid C cells and medullary carcinomas

An increasing number of regulatory peptides not coded by the calcitonin genes are known to occur in the thyroid C cells. We have now carried out light and electron microscopic immunocytochemical analyses on specimens of normal human thyroids and medullary carcinomas to establish the occurrence of members of the PP-PYY-NPY family in the C cell system. By means of site-directed immunocytochemistry we provide the first evidence that a molecule closely related to proNPY is present in normal and pathologic C cells, and is co-stored with calcitonin in the cytoplasmic dense-core granules. Preliminary observations also suggest that high levels of expression of NPY-gene products help to define a subset of tumours with a less aggressive behaviour.

Immunocytochemical localization and identification of prosomatostatin gene products in medullary carcinoma of human thyroid gland

Thirty-three cases of histologically proven calcitonin-positive medullary thyroid carcinoma were studied immunocytochemically for the occurrence of prosomatostatin-related peptides. Positive cells, identified with a panel of antisera raised against four different regions of the prosomatostatin molecule, were found in 100% of the tumors. Most but not all somatostatin-positive cells were also immunoreactive for calcitonin. Notably, seven patients harboring somatostatin-rich tumors revealed a more favorable clinical course. The results (1) indicate that somatostatin production is a universal concomitant of thyroid medullary carcinoma, (2) suggest that these cells are likely to produce a somatostatin precursor molecule similar to mammalian prosomatostatin, and (3) imply that somatostatin-reactive cells may have as yet unknown roles in these tumors, possibly in the realm of paracrine and autocrine regulation of cell growth.

Maternal and perinatal issues regarding HIV infection

A review of the information available regarding maternal and fetal factors involved in both protection from and infection with HIV raises more questions than answers. Although providing prevention of HIV infection in women and infants is the ultimate goal, the recent increases in HIV seroprevalence among women of childbearing age gives little hope that this approach will have an effect in the near future. Early detection of HIV infection in pregnant women may provide the opportunity to counsel, provide routine obstetric care, and consider early therapeutic intervention with antiretroviral therapy and active or passive immunotherapy. Identification of HIV-infected infants before they are symptomatic is an equally important goal, as similar therapeutic options may be used.

Long-term treatment of metastatic medullary thyroid carcinoma with the somatostatin analogue octreotide

Three patients with symptomatic metastatic medullary thyroid carcinoma (MTC), one with sporadic form and two with MEN IIa, were treated with the long-acting somatostatin analogue octreotide (SMS 201-995, Sandoz) for 3 to 17 months. Octreotide was administered subcutaneously in a starting dose of 0.6 to 1.0 mg/day by automatic pump (Travax ASH6, Travenol). Symptoms of diarrhoea, weight loss and malaise improved in all patients. Maximal percentage decrease in mean serum calcitonin was 47, 52 and 81% of the basal values, and was observed 1-3 months from the beginning of treatment. Likewise, carcinoembryonic antigen (CEA) levels initially dropped to 45, 60 and 63% of the levels before therapy. A continuing effect was seen in the two patients with MEN IIa after 15 and 17 months of treatment. However, after the initial decrease, calcitonin (CT) levels went up again to 67 and 68% of the basal values and the dose of octreotide had to be increased to 1.5 mg and 2.0 mg/day. CEA also returned to 84 and 105% of the pretreatment titres. Response to 1.5 mg/day octreotide was lost in the patient with the sporadic form of disease after 3 months. Side-effects were minimal. Effects on tumour size could not be evaluated. These suggest that octreotide might be a valuable adjuvant in the long-term management of metastatic MTC. Tachyphylaxis may occur.

The value of neonatal serum thyroglobulin determinations in the follow-up of patients with congenital hypothyroidism

Serum thyroglobulin was determined in 68 newborn infants with positive screening tests for congenital hypothyroidism. In 38 infants the diagnosis was confirmed (patients), but the remaining 30 were euthyroid at follow-up (controls). The mean thyroglobulin concentration at the age of 2 weeks did not differ significantly between the patients and the controls (179 vs. 125 micrograms/l). Thyroid scintigraphy was performed in 15 patients. All seven with thyroid aplasia, based on 99mTc pertechnetate scintigraphy, had measurable thyroglobulin (greater than 2 micrograms/l) and thyroid hormones in their serum. This indicates that total absence of thyroid tissue is very rare in Swedish patients with congenital hypothyroidism. Scintigraphy based on 99mTc does not permit detection of small amounts of thyroid tissue. The neonatal concentrations of thyroglobulin did not correlate with the results of Griffiths test at 3 years and are therefore not useful for prognosis of psychomotor development. We conclude that neonatal measurement of thyroglobulin is of limited value in the follow-up of patients with congenital hypothyroidism.

Diffuse sclerosing variant of papillary thyroid carcinoma. S-100 protein immunocytochemistry and prognosis

The recently published second edition of the WHO classification of thyroid tumours describes the diffuse sclerosing papillary carcinoma (DSPC) as a specific variant of papillary thyroid cancer (PC). Besides several histological hallmarks, this rare tumour is characterized by its occurrence in young individuals and is thought to have a less favourable prognosis than PC in general. The observations on two examples of this tumour presented herein, however, are at variance at this assumption. The neoplasms occurred in a 10 year old girl and a 34 year old woman. Each time, diffuse involvement of both thyroid lobes and bilateral cervical lymphadenopathy were seen. In one case, the carcinoma extended into the cervical soft tissue. Follow-up disclosed both patients to be without evidence of disease 2 and 13 years, respectively, after thyroid surgery. Immunocytochemically, both thyroid primaries as well as 7 other cases of DSPC reported in the literature showed dense accumulations of S-100 protein positive dendritic/Langerhans cells. Such infiltrations have been demonstrated to be correlated with a benign clinical course of PC. It is thus suggested that DSPC behaves similarly or even less aggressively than PC in general, at least if prominent Langerhans cell infiltration is present.

Effects of repeated stress on T cell numbers and function in rats

Although stress has been reported to affect various functions of the immune system, the mechanism that mediate these effects remain unclear. Thus we examined the effects that 1, 7, and 14 days of stress could have on various aspects of immune and endocrine function in rats. Rats subjected to repeated stress (7 and 14 days) showed significant decreases in the total number of mononuclear cells, particularly suppressor/cytotoxic (CD8) T cells, in the spleen and blood. The mitogenic responses of T cells to phytohemagglutinin (PHA) and concanavalin-A (Con A) were also significantly diminished at these times, as well as after acute (1 day) stress in the case of PHA stimulation. The mechanisms of this impaired T cell mitogenesis were explored by assessing the effects of stress on T cell interleukin 2 (IL-2) production and T cell responsiveness to IL-2. T cells from repeatedly stressed rat showed a decreased production of IL-2 in response to PHA, although their proliferative response to exogenous IL-2 was normal. Repeated stress also decreased body weight and spleen weight, increased adrenal weight, and decreased plasma levels of triiodothyronine and testosterone. These results suggest that lower levels of IL-2 production during stress could be one reason for the decreased mitogen responsiveness of T cells, often seen with stress. This is important because defective IL-2 production could also lead to significant impairment of immunoregulatory T cell generation and thus a predisposition to malignancy or autoimmune disease that some have associated with stress.

Thyroid carcinoma in Graves' disease

The pathogenesis of thyroid carcinoma in Graves' goiter is still obscure and the methods for preoperative diagnosis of such carcinomas is not well established. We studied the incidence, clinical features, and pathological findings of thyroid carcinoma in Graves' goiter. From October, 1983 to September, 1985, a total of 739 patients with Graves' disease underwent subtotal thyroidectomy at Ito Hospital, Tokyo. All of these patients underwent roentgenography of the neck before surgery. Thyroid carcinoma was revealed in the resected specimen in 15 (2.0%) of 739 patients. During the same period, another 4 patients underwent surgery for thyroid carcinoma who had had Graves' disease previously and these 4 cases were included in the present study. The incidence of thyroid carcinoma associated with Graves' disease was 2.6% (19 of 743 cases). Histological examination revealed 15 papillary and 4 follicular carcinomas. The size of the carcinoma foci was 13.8 +/- 15.6 mm in diameter (range: 1-60 mm), 10 (52.6%) foci being 10 mm or greater. Invasive growth into the surrounding thyroid tissue was predominant and regional lymph node metastasis was noted in all 6 patients who underwent cervical dissection. Preoperative roentgenography revealed calcification in 5 (26.3%) of 19 cases. Our present study indicates that thyroid carcinoma in Graves' goiter may show markedly invasive growth with lymph node metastasis even though the primary tumor is small in size, and it is suggested that the detection of calcification may serve as a part of the diagnostic measures when the carcinoma focus is difficult to palpate in the diffusely-enlarged Graves' goiter.

Zinc and thymic hormone-dependent immunity in normal ageing and in patients with senile dementia of the Alzheimer type

Plasma zinc levels were measured in young controls, aged controls, patients with dementia of the Alzheimer type and patients with non-Alzheimer type dementia. Zinc levels decreased with age; however, no difference was found between patients with dementia and age-matched controls. Plasma levels of active or inactive thymulin, a nonapeptide produced and released by the thymus gland, were also determined in young controls, aged controls, patients with dementia of the Alzheimer type and patients with non-Alzheimer type dementia. Basal levels of active thymulin were decreased in aged controls and in patients with dementia. In vitro reactivation of thymulin after zinc addition to plasma samples was decreased in aged controls. A further impairment of thymulin reactivation was present in patients with dementia. A significant age-dependent decrease in lymphocyte proliferation after mitogen stimulation was found; however, no difference was present between aged controls and patients with dementia of the Alzheimer type. Interleukin-2-induced cell activation and its effect on mitogen-induced proliferation were also measured; once again only an age-associated decrease was found. The endocrine function of the thymus of patients with dementia appears to be more compromised than that from aged controls.

Ophthalmopathy in early thyrotoxicosis--relationship to thyroid receptor antibodies and effects of treatment

A prospective study of 25 newly diagnosed thyrotoxic patients was undertaken to determine the incidence and severity of ophthalmopathy in the early stages of the disease. A quantitative analysis of the ocular muscle changes was made using B scan ultrasonography, and the effects of treatment for the thyroid disease on the course of the eye changes was assessed. Although the majority (75%) of patients showed only mild clinical signs of ophthalmopathy (Werner Class 3 or less), 92% had ultrasonographic evidence of ocular muscle enlargement. Clinical involvement of the extraocular muscles was seen in 12% of the cases. There was an inverse correlation between the serum level of thyroid stimulating hormone receptor antibody (TR Ab) and the size of the extraocular muscles. Recovery of the euthyroid state with treatment was accompanied by a decrease in orbital infiltration in some cases, both clinically (reduced amplitude of intraocular pressure rise on elevation of the globe) and by ultrasonography, but the improvement was not statistically significant.

Systemic lupus erythematosus and the maternal-fetal dyad

Since systemic lupus erythematosus most frequently affects women of childbearing years, the management of patients during pregnancy is an important and common problem facing the clinician. This review concerns the effects of pregnancy on the course of maternal disease and fetal well-being. On the maternal side are the problems of renal disease which may exacerbate and be difficult to differentiate from pre-eclampsia especially when occurring in the third trimester. An active urinary sediment, falling C3 and CH50 and elevated complement split products of the alternative pathway and terminal attack complex may serve as useful parameters of lupus activity. In general, maternal disease is not an imposing threat and prospective studies suggest that the exacerbation rate is not significantly greater in the pregnant lupus patient than in the non-pregnant patient. On the fetal side are the problems of placental insufficiency and in utero attack on developing organs. Maternal antibodies such as those reactive with negatively charged phospholipids are associated with second trimester miscarriages and suggested, but not firmly established, thrombosis of placental vessels. The placental transfer of maternal antibodies against components of the rapidly expanding group of SSA/Ro-SSB/La ribonucleoproteins is strongly implicated in the transient and permanent manifestations of neonatal lupus. Using various techniques for defining the specificity of the antibody response most associated with heart block, the data suggest that mothers whose sera contain antibodies which recognize antigens of SSA/Ro-SSB/La on SDS-immunoblot are at greatest risk. In the absence of antibodies to SSB/La, mothers whose sera contain antibodies reactive only to bovine SSA/Ro by ELISA do not appear to be at high risk. A rational approach to in utero treatment of autoantibody mediated fetal myocarditis includes plasmapheresis and the use of dexamethasone. Finally, the safety of the commonly used medications for the treatment of lupus such as the nonsteroidal anti-inflammatory agents, glucocorticoids and anti-malarials during gestation and breast feeding, is addressed.

Severe hyperthyroidism due to metastatic papillary thyroid carcinoma with favorable outcome

A case of extremely severe hyperthyroidism due to bone metastasis of papillary thyroid cancer is described. Hyperthyroidism began in this patient soon after the discovery of pelvic metastasis and worsened after total thyroidectomy and after the first dose of radioiodine. The administration of methimazole, prednisone and multiple, fractioned and small doses of radioiodine cured the hyperthyroidism and stabilized the neoplastic growth. Hyperthyroidism lasted for at least six months and hypothyroidism appeared only after seven months. Thus, the fractionation of the doses of radioiodine together with antithyroid drugs appears to be an effective treatment in patients with hyperthyroidism due to metastatic thyroid cancer.

Measurement of serum thyroglobulin is of value in detecting tumour recurrence following treatment of differentiated thyroid carcinoma by lobectomy

Serum thyroglobulin was measured in 243 samples from 84 patients (20 men and 64 women, with a mean age of 48.9(14) years) with differentiated thyroid carcinoma treated by lobectomy, and in 58 patients treated by total thyroidectomy. Both groups were given thyroxine to suppress thyroid stimulating hormone (TSH). Three patients in the lobectomy group and eight in the thyroidectomy group had evidence of tumour recurrence. Serum thyroglobulin concentration was elevated in the presence of known recurrent tumour (P less than 0.001) irrespective of the type of operation, and in its absence tended to be higher in the lobectomy than in the thyroidectomy group (median 4 micrograms/l versus 2 micrograms/l, P less than 0.05). Serum thyroglobulin levels of less than 10 micrograms/l could confirm the absence of otherwise known tumour recurrence in both groups with a specificity of 100 per cent, and sensitivities of 80 per cent and 86 per cent in the lobectomy and thyroidectomy groups respectively. Exclusion of samples liable to spurious elevation of thyroglobulin improved the sensitivity in the lobectomy group to 92 per cent. Despite the presence of residual thyroid tissue, measurement of serum thyroglobulin can exclude the presence of significant metastases in most patients following lobectomy for thyroid carcinoma.

Thymic hormones and prostaglandins. II. Synergistic effect on mouse spontaneous rosette forming cells

Prostaglandins (PGs) have been assumed to play a role in the biological activity of thymic hormones (TH). Indeed, it has been shown that type E-PGs are able to mimic the action of several TH. Moreover, indomethacin interferes in the rosette assay, which still represents the most commonly used bioassay for the evaluation of TH and, in particular thymulin levels, in biological fluids. Previously, our attempt to modulate PG production by different TH showed that none of the TH tested affect PGE2, 6-keto-PGF1 alpha, PGF2 alpha and TXB2 production by spleen cells from control and thymectomized (Tx) mice, while indomethacin was able to inhibit the spontaneous PG production. Here, we investigated a possible role for each endogenously produced PG in the experimental conditions of the rosette assay, in order to define: 1) whether or not there was a specificity of action of a given PG; and 2) to analyze the pattern of action between thymulin and the endogenously produced PGs. We demonstrated that PGE2 and 6-keto-PGF1 alpha are the PGs which are physiologically involved in the rosette assay, according to their levels of endogenous production, and that they are able to synergize with thymulin. This synergy was demonstrated in two ways: 1) by adding anti-PGE2 and anti-6-keto PGF1 alpha-antibodies, which prevent part of the thymulin effect, or 2) by simultaneous addition of PG and thymulin, at concentrations far lower than those which correspond to their thymulin-like effect. Moreover, PGE2 addition, at concentration close to that found to be endogenously produced, partially reversed the indomethacin-induced effect in the rosette assay. In conclusion, if PGs do not act as mediators of thymulin, they are able to synergize in one of its biological action.

Transthyretin--an explanation of "anomalous" serum thyroid hormone values in severe illness?

The following serum analytes were measured in 464 patients with defined carcinomas and other tumours as well as those with chronic obstructive lung disease and under regular haemodialysis, and in 261 healthy controls: thyrotropin (TSH), thyroxine (T4), triiodothyronine (T3), free thyroxine (fT4), thyroxine binding globulin (TBG) and transthyretin (TTR). The following ratios were constructed: fT4 x TTR, defined as the thyroxine availability index fT4/TTR, defined as the thyroid hormone compensation index 100 x T3/TBG as the free T3 index (fT3I) and fT3I x TTR, defined as the triiodothyronine availability index. Significantly elevated thyrotropin values (p = 0.05) were only found in patients with breast cancer when compared with age matched controls, although elevated T4 and fT4 values were found in all experimental groups except the haemodialysis patients (p less than 0.01). The thyroxine availability index and triiodothyronine availability index values were not significantly different from the age matched controls (greater than 60 a) in the cancer groups, showing that the transthyretin concentrations compensated for changes in fT4 or vice versa. These findings are reflected in the euthyroid thyrotropin values. The T4 and fT4 values in the dialysis patient group were significantly lower than in the age matched controls (p less than 0.01), while the transthyretin values were significantly higher (p less than 0.01), which accounted for the normal thyroxine availability index and euthyroid thyrotropin values.

Neuroendocrine-thymus interactions. I. In vitro modulation of thymic factor secretion by thyroid hormones

Several in vivo experimental and clinical studies suggest that the production of thymic hormones, such as thymulin (Zn-FTS), is modulated by thyroid hormones. It was not determined in these studies, however whether such modulation is exerted directly on the thymic epithelial cells which synthesize and secrete thymic hormones. In order to discriminate between direct and indirect modulation, the effect of thyroid hormones on the in vitro production of thymulin by whole thymic organ culture, as detected by the rosette inhibition assay, has been investigated. Donors of thymuses were young 6N-propyl-2 thiouracil (PTU)-treated hypothyroid Balb/c mice and normal littermates. Thymuses from hypothyroid mice were shown to produce concentrations in vitro nearly undetectable of thymic hormone, when compared to thymuses from normal mice. The in vitro addition of triiodothyronine (T3) caused a complete recovery of the thymic hormone production by thymuses from hypothyroid mice and an increased synthesis even by normal thymuses over control values. The complete blockade of in vitro thymic hormone production with cycloheximide, which inhibits mRNA and protein synthesis but not thyroid hormone permissive actions, suggests that the T3 induced increment of thymic hormone level in the supernatant is due to de novo synthesis. Furthermore, the number of thymulin-producing cells, as detected by immunofluorescence using a specific antithymulin monoclonal antibody, which is quite low in thymuses from hypothyroid mice, is completely regained after in vitro incubation with T3. These findings support the idea that the modulation of thyroid hormones on thymic endocrine activity is directly exerted at thymic level.

The intratumoral immunoassayable somatostatin concentration is frequently elevated in medullary thyroid carcinoma. Results in 34 cases

The current work has been performed by the Cooperative French Group of Medullary Thyroid Carcinoma (GETC). A systematic evaluation of RIA somatostatin (SRIH) was performed in 34 medullary thyroid carcinomas (MTC) (25 inherited, seven sporadic). Plasma SRIH was measured by radioimmunoassay in parallel with calcitonin (CT) and carcinoembryonic antigen (CEA). Immunoassayable SRIH was tested in fresh tumoral tissue samples from the same 34 MTC and, for comparison, in 10 nontumoral thyroid extracts (less than 6 pmol/g wet). Although plasma SRIH was only slightly elevated in two of 20 cases, tumoral SRIH was elevated in 70.6% of our MTC (10 to 3973 pmol/g). The chromatography of two tumoral extracts showed that somatostatin 14 was the major molecular form. We found no correlation (P greater than 0.1) between tumoral SRIH and the following: (1) tumor size (r = 0.227); (2) epidemiologic form of MTC (r = 0.144); (3) plasma SRIH (r = 0.045), plasma CT (R = 0.095) or (4) plasma CEA (r = 0.032). Thus, in the authors' experience, SRIH appears as a major product of tumoral C-cell in human MTC, even when plasma SRIH is normal and SRIH immunohistochemical staining is scarce. Multiple hormonal production of these tumors may explain its presence but SRIH may act also as a regulator, since negative influence of SRIH on CT is demonstrated in normal as well in tumoral conditions.

Parathyroid cyst: report of case in the mediastinum

Though a rare lesion a parathyroid cyst is of clinical significance because it usually mimics a thyroid cyst and can be associated with hyperparathyroidism. The cyst can be ectopic with location in the lateral neck or in the mediastinum and therefore constitutes a differential diagnosis to a branchial or thymic cyst. A case report of a mediastinal parathyroid cyst without hyperparathyroidism is presented. Fine needle aspiration with parathyroid hormone assay on the cyst fluid will reveal the correct diagnosis. Surgical removal of the cyst is recommended, and hyperparathyroidism should be considered.

Changes in circulating levels of neuroendocrine and thymic hormones during aging in rats: a correlation study

It is well established that during early life the thymus gland and the neuroendocrine system influence each other's maturation. Furthermore, there is a growing body of evidence indicating that the immune and neuroendocrine systems also function as a bidirectional network during adult life. In order to assess possible changes in the thymic-neuroendocrine network during aging, we undertook to measure and correlate the circulating levels of several neuroendocrine and thymic hormones in young (3 month) and old (26 month) male Sprague-Dawley rats. Sequential plasma samples were obtained from chronically cannulated, nonstressed animals every 30 min for 5 h. Two days later rats were killed between 11:30 a.m. and 1:30 p.m. and trunk serum was obtained. All hormones were measured by radioimmunoassay. Growth hormone (GH), prolactin (PRL), thyrotropin (TSH) and corticosterone were measured in plasma, whereas thyroxine (T4), triiodothyronine (T3), thymosin alpha 1 (T alpha 1) and thymosin beta 4 (T beta 4) were determined in trunk serum. The circulating levels of T3, PRL, corticosterone and T beta 4 did not show significant differences between young and old rats, whereas GH, T4, T alpha 1, and thymus weight showed a significant age-related reduction. The anterior pituitary (AP) weight and plasma TSH were significantly higher in old than in young rats. Three pairs of parameters showed highly significant levels of linear correlation: AP weight vs. T alpha 1; thymus weight vs. T4 and T alpha 1 vs. T4 (p less than 0.01, p less than 0.001 and p less than 0.001, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Recovery of low thymic hormone levels in cancer patients by lysine-arginine combination

Thymic hormones are required for maturation and maintenance of the immune efficiency. It has been previously demonstrated that with advancing age there occurs a progressive reduction of the plasma level of one of the best known thymic peptides, i.e. thymulin, and that the administration of an amino acid combination (lysine-arginine, as present in the commercial preparation Lysargin, Baldacci, Italy) to elderly individuals is able to increase the synthesis and/or release of thymulin to values comparable to those recorded in young subjects. In the present paper we report evidence that cancer patients show much lower thymulin values than those recorded in healthy age-matched individuals and that the oral administration of the amino acid preparation is able to significantly increase thymulin levels even over the values of age-matched controls and to increase the number of peripheral T-cell subsets. It is suggested that such an effect is mediated through the known secretagogue activity of the amino acids on the pituitary release of growth hormone, which has a modulating effect on the thymic endocrine activity.

Neuroendocrine control of thymic hormonal production. II. Stimulatory effects of endogenous opioids on thymulin production by cultured human and murine thymic epithelial cells

Data have now accumulated to strongly demonstrate that several neuropeptides, including endogenous opioids, can have immunomodulatory functions. Most of the studies have so far focused on the direct action of these substances on lymphocytes. We decided to investigate whether thymic epithelial cells (TEC) - the major component of the thymic microenvironment - could also be modulated by endogenous opioids. Primary cultures of human and murine TEC were subjected to several opioids (alpha-beta- or gamma-endorphins, as well as met- or leuenkephalins) applied in concentrations ranging from 10(-6) to 10(-9) M. On the following days we measured the levels of thymulin (a chemically-defined thymic hormone known to stimulate some steps of T-cell differentiation) in the culture supernatants, as well as the numbers of thymulin containing cells, evaluated by immunofluorescence with an anti-thymulin monoclonal antibody. After treatment of TEC cultures with beta-endorphin or leu-enkephalin a significant increase in the levels of thymulin in the culture media was observed, paralleled by a rise in the percentage of thymulin containing cells. In addition, this stimulatory effect was dose-dependent. Preincubation of the opioids with the specific antibodies abrogated the opioid-induced stimulatory effect on TEC. Moreover, naloxone, an opioid receptor antagonist, blocked the effect of beta-endorphin on thymulin production, suggesting that the effect of this neuropeptide on epithelial cells was mediated by an opioid receptor. Importantly, no effect on thymulin production was observed with the other opioids used, whatever the dose. These results suggest that, at least in vitro, beta-endorphin and leu-enkephalin stimulate the hormonal function of the thymic epithelium. These findings lead to the general concept that the modulatory role of endogenous opioids on the immune system is not restricted to lymphocytes but can also take place at the level of cells belonging to T-cell differentiating microenvironments.

Increased interleukin 2 receptor expression in post-gestational women: relationship to impaired glucose tolerance and islet cell antibodies in pregnancy

Fifteen women with positive islet cell antibodies were identified in a group of 115 consecutive patients found to have impaired glucose tolerance in pregnancy. These subjects were postulated to be at increased risk of later developing type 1 diabetes mellitus. They were examined post--partum for HLA types known to be associated with this disease and for any increase in Interleukin 2 receptor expression or alteration of T cell subsets of possible relevance to its pathogenesis. Fifteen women negative for islet antibodies and with normal glucose tolerance during previous pregnancy and 15 women with a normal fasting plasma glucose who had never been pregnant were studied as controls. Using flow cytometric techniques a significant increase in both the number and proportion of activated (Interleukin 2 receptor, CD25) lymphocytes in the peripheral blood of women who had islet cell antibodies and previous impaired glucose tolerance in pregnancy was found (0.14 +/- SE 0.03 x 10(9)/l; 7.1 +/- 1.1%) when compared with normal parous controls (0.09 +/- 0.01 x 10(9)/l; 4.2 +/- 0.6%), p less than 0.01 x 10(9)/l; showed significant increases when compared with nulliparous controls (0.04 +/- 0.01 x 10(9)/l; 2.1 +/- 0.2%), p less than 0.01. No differences were detected between the three groups with respect to total T-lymphocytes (CD3), helper T-lymphocytes (CD4), suppressor cytotoxic T-lymphocytes (CD8), or the inducer of suppressor (Leu 3+/Leu 8+) subset of T-lymphocytes. Three women persistently islet cell antibody positive, two of whom were HLA DR4, showed impaired glucose tolerance at the time of lymphocyte subset analysis, while two further patients, one DR3 and the other DR4, had developed type 1 (insulin-dependent) diabetes. No correlation between increased Interleukin 2 receptor expression and glucose intolerance was demonstrated. We conclude that islet cell antibody positive women with impaired glucose tolerance during pregnancy are at increased risk of later developing type 1 diabetes but that heightened immune activation present in these women is in part a post-pregnancy phenomenon.

Control of breathing in patients with short-term primary hypothyroidism

In 8 patients (3 men and 5 women) with short-term primary hypothyroidism before and during replacement therapy, and in an age-matched control group (9 men and 7 women), we assessed maximal inspiratory muscle force (Pimax) and the ventilatory control system at neural (EMG), muscular (P0.1), and ventilatory (VE and Vt/Ti) levels. While hypothyroid, patients exhibited a significantly lower Pimax. During a CO2 rebreathing test, hypothyroid patients exhibited similar diaphragmatic electromyographic (EMGd) and ventilatory (VE) response slopes to increasing end-tidal CO2 tension (delta EMGd/delta Pet CO2 and delta VE/delta PetCO2), but significantly less delta P0.1/delta PetCO2 (p less than 0.05) and delta(Vt/Ti)/delta PetCO2 (p less than 0.05) response slopes. During replacement therapy with L-triiodothyronine (L-T3), Pimax (p less than 0.05), delta P0.1/delta PetCO2, and delta(Vt/Ti)/delta PetCO2 response slopes were found to be significantly increased (p less than 0.05 for both) while neither EMGd nor VE response changed significantly. We concluded that short-term hypothyroidism does not seem to be associated with blunted neural inspiratory output (EMGd), the respiratory control system seems to be affected mostly at a peripheral (muscular) level, and L-T3 increases both force (P0.1 and Pimax) and velocity (Vt/Ti) of inspiratory muscle contraction.

Immunoheterogeneity of parathyroid hormone in parathyroid cysts: diagnostic implications

Parathyroid cysts are uncommon lesions of the neck leading to hypercalcemia in a significant percentage of cases. The distinction between parathyroid and thyroid cysts is difficult to make on a clinical basis alone and relies on the demonstration of elevated PTH levels in cyst fluid. We describe a case of a parathyroid cyst in which intact PTH (1-84) levels were misleadingly low while midmolecule 44-68 PTH was markedly elevated. To explain this discrepancy, we studied cyst fluid from this and two other patients using Sephadex G-75 gel chromatography. Fractions were analyzed using an immunoradiometric assay for intact hPTH (1-84) and a RIA specific for the midmolecular 44-68 region of hPTH. Immunoreactivity corresponding to hPTH (1-84) was absent in the first case but present in the remaining two. Immunoreactive peaks corresponding to PTH fragments were demonstrable in all three cyst samples. Patients with elevated hPTH (1-84) in cyst fluid were hypercalcemic; in contrast, the patient with a low cyst level of hPTH (1-84) was normocalcemic despite having markedly elevated levels of midmolecule PTH (44-68) in both serum and cyst fluid. Parathyroid cysts may thus produce fragments rather than intact PTH; reliance on an intact hPTH assay could lead to misdiagnosis. The measurement of PTH by a midmolecular assay may be preferable to the measurement of intact PTH in the evaluation of fluid from cystic neck masses.

The significance of T suppressor cells in the development of autoimmunity

Despite intensive research, autoimmune-disease pathogenesis is still an enigma, but in the past decade Ts-cell defects have assumed a central role in this pathogenesis. Ts-cell dysfunctions have been reported in numerous autoimmune diseases (e.g. SLE, autoimmune thyroid disease, myasthenia gravis) and in animal models of autoimmune diseases. Therefore, it is currently believed that Ts cells are responsible for maintaining self-tolerance and that perturbations in suppressor functions may initiate development of autoimmune diseases. Ts-cell abnormalities can result from LCTA production, intrinsic biochemical alterations, genetic susceptibility, or environmental factors. Since Ts-cells dysfunctions are believed to initiate autoimmunity, it may be possible to treat autoimmune diseases by correcting the suppressor defects, and indeed, preliminary trials in this direction are promising.

Immunomodulatory effect of methimazole on inbred mice

The effects of antithyroid drug, methimazole (MMI, 1-methyl-2-mercaptoimidazole), on the immune system of inbred mice, C57BL/6, were studied. The proliferative response of splenic lymphocytes to concanavalin A (Con A) and allogeneic stimulator cells was reduced when the mice were provided with 0.1% MMI in tap water ad libitum for two to four weeks. The reduction of proliferative response was correlated with a lower frequency of proliferative spleen cells in the MMI-treated mice. The ability to produce macrophage activating factor of these spleen cells and the levels of hemolytic plaque-forming cells were also reduced. However, the mitogenic response of the splenic lymphocytes to lipopolysaccharide (LPS) was enhanced. In order to investigate whether the impaired cell-mediated and humoral immune systems would increase the susceptibility of the MMI-treated animal to the growth of tumor cells, mice were challenged with a lethal dose of Moloney virus-induced T cell lymphoma of C57BL/6 mice (MBL-2). The time required for 50% of the animals to die was reduced from 15 days for the normal mice to 10 days for the MMI-treated mice.

Immunosuppression in pregnant women infected with human immunodeficiency virus

One hundred two pregnant women at high risk of infection with the human immunodeficiency virus (62 who were drug abusers and 40 of Haitian origin) were prospectively examined for immunologic changes during and after pregnancy. Among the 63 human immunodeficiency virus-negative women, levels of CD4+ (helper) cells fell to a nadir at 8 weeks before delivery and rose rapidly just before delivery. The level of CD8+ (cytotoxic/suppressor) cells rose slowly from midpregnancy to delivery. Among the 37 human immunodeficiency virus-positive pregnant women, levels of CD4+ cells fell during pregnancy (except for a transient weak increase just before delivery) and did not recover in the postpartum period. Levels of CD8+ cells were consistently higher in human immunodeficiency virus-positive than human immunodeficiency virus-negative women. Post partum the CD8+ cells in human immunodeficiency virus-negative women stabilized at delivery levels, whereas they increased greatly in human immunodeficiency virus-positive women. The loss of CD4+ cells in human immunodeficiency virus-positive women appeared to be faster during pregnancy than in the postpartum period. These data support the hypothesis that pregnancy may accelerate human immunodeficiency virus-induced depletion of CD4+ cells and increase the risk of acquired immunodeficiency syndrome.

Clinical evaluation of serum thyroglobulin measurement using a commercial kit in the diagnosis of recurrent thyroid cancer

The value of serum thyroglobulin assay employing a kit manufactured by Diagnostic Products Corporation in the detection of recurrence of thyroid carcinoma in patients treated by thyroidectomy and ablative therapy was assessed by clinical follow-up and radioiodine scanning of 122 patients over a 2-year period. A total of 204 specimens were analysed. The assay was found to be sensitive and highly specific for the detection of recurrent thyroid carcinoma provided that lipemic sera are clarified by ultracentrifugation prior to measurement and that results from those patients who demonstrate positive serum antithyroglobulin antibodies are excluded. The predictive value of a serum thyroglobulin level above 20 pmol/L was 96% for recurrence of thyroid carcinoma. The predictive value for non-recurrence was 98% for serum thyroglobulin levels below 10 pmol/L. The specificity and sensitivity of the assay were poor for serum thyroglobulin levels between 10 and 20 pmol/L. In recurrence-free patients, the serum thyroglobulin levels were not changed by withdrawal of thyroid replacement therapy 4-7 weeks prior to sampling.

Male BXSB mice develop a thymic hormonal dysfunction with presence of intraepithelial crystalline inclusions

The thymus is morphologically abnormal in male BXSB mice with cortical involution densification of the epithelium and the presence of intraepithelial crystals. The thymic endocrine function in BXSB mice was appraised using a biological assay to measure the level of the zinc-dependent thymic hormone, thymulin, and an indirect immunofluorescence technique to evaluate the number of cells synthesizing the hormone within the thymus. Unlike the dramatically accelerated age-linked decline of thymulin production reported in females of other autoimmune strains (measured as early as 6 weeks of age), only male BXSB were affected, as compared to normal strains. The number of hormone-producing cells was significantly reduced in male BXSB thymuses, in parallel with this hormonal decrease. Thymulin inhibitory molecules were detected in male BXSB sera, as early as 8 weeks of age, as evaluated by their capacity to absorb in vitro and in vivo the biological activity of the hormone. These inhibitors are thymus dependent since they disappear after adult thymectomy. They are low MW molecules (less than 10 kDa), as previously found in normal aging mice, rather than autoantibodies, as evidenced in two autoimmune strains (B/W and db/db mice). These findings demonstrate that male BXSB mice develop thymic abnormalities very similar to those observed in other autoimmune strains. The presence of intrathymic crystals and of low MW inhibitors suggests the role of abnormal storage and the excretion of thymulin. This thymic dysfunction may play a role in the maintenance of B cell hyperactivity previously shown in BXSB males.

Studies on the thymus in Chagas' disease. I. Changes in the thymic microenvironment in mice acutely infected with Trypanosoma cruzi

Previous observations demonstrated severe thymocyte depletion in mice undergoing acute Chagas' disease. These data led us to investigate the status of the thymic microenvironment in these animals. Young adult C57BL/6 and C3H/HeJ mice were infected i.p. with 10(5) blood-derived trypomastigote forms of Trypanosoma cruzi (CL strain) and killed 7-14 days after infection. Sera were then analyzed for thymic hormone (thymulin) levels, and frozen thymus sections were studied by immunohistochemistry for the expression of functional antigens (thymulin and Ia), the distribution of distinct thymic epithelial cell subsets and extracellular matrix components. Infected mice exhibited a transient decrease in thymulin production and those with severe thymic atrophy showed a denser Ia-bearing cellular network. In addition, an abnormal localization of the TR5 and CK18 antigens restricted to the medullary and cortical TEC subsets, respectively, was observed. Furthermore, an increase in the basement membrane proteins was detected within thymic lobules. We suggest that the thymic microenvironment is also affected during T. cruzi infection, extending the concept that the thymus should be regarded as a target in Chagas' disease.