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PubMed2006

[Clinical features and diagnosis of langerhans cell hyperplasia].

BACKGROUND & OBJECTIVE: The incidence rate of langerhans cell hyperplasia (LCH) is increasing. Its clinical manifestation is so diversified that it is easy to be misdiagnosed. This study was to analyze its clinical features for the sake of early diagnosis and treatment. METHODS: Clinical data of 44 LCH patients, treated from Jan. 1990 to Dec. 2003 in the First Affiliated Hospital of Sun Yat-sen University, were retrospectively analyzed. RESULTS: Of the 44 LCH patients, 32 (72.7%) were children, 12 (27.3%) were adults. Of the 32 children patients, 15 (46.9%) were less than 2 years old. The involved organs were bone (20/44, 45.5%), lymph nodes (20/44, 45.5%), skin (16/44, 36.4%), liver and spleen (16/44, 36.4%), lung (14/44, 31.8%), bone marrow (6/44, 13.6%), ear (4/44, 9.1%), eyes (2/44, 4.5%), pituitary gland (2/44, 4.5%), and thymus gland (1/44, 2.3%). Of the 44 patients, 10 had 1 organ involved, 11 had 2 organs involved, 9 had 3 organs involved, 7 had 4 organs involved, 7 had no less than 5 organs involved; 22 children patients and 4 adult patients had multiple organs (liver, lung, bone marrow, and so on) involved; 26 (59.1%) were misdiagnosed as dermatosis (6 cases), hemopathy (7 cases), bone or bone marrow diseases (7 cases), lung tuberculosis (2 cases), diabetes insipidus (2 cases), ear or eye disease (2 cases). Six children patients had bronchopneumonia, and 4 of them had septicemia. Six patients died with 5 cases below the age of 2. CONCLUSIONS: LCH is easy to be misdiagnosed. Children below 2 years old tend to complicate with multiple organ failure (MOF) and bronchopneumonia which have high death rate. Pathology examination is helpful for early diagnosis, treatment, and prevention of severe complications.

Adolescent↗
PubMed1983

Immunological reconstitution of nude mice transplanted with human malignant tumours.

The effects of neonatal murine thymus grafts implanted in nude mice previously transplanted with three different human malignant tumours were studied. Reconstitution resulted in tumour rejection, which started 2-3 weeks after thymus implantation and was complete after 3-6 weeks. The rejection process showed a characteristic histologic picture with 3 phases, an early, an intermediate, and a late phase, which were similar in the 3 tumour types examined. Histological examination of lymphoid tissues of successfully thymus grafted mice showed reconstitution of varying degrees. Numbers of plaque forming cells (PFC) of the spleen of tumour transplanted, thymus grafted mice were equal to or higher than the numbers of PFC in normal BALB/c controls. Mice, thymus grafted only always showed intermediate PFC-values. Responses to the T-cell mitogen, phytohaemagglutinin-P (PHA) were only partially reconstituted, whether the nude mice were tumour transplanted or not. In addition tumour rejection in tumour-bearing nude mice treated with T-cells only, was studied. The rejection process was similar to that observed when a whole thymus gland was implanted. Finally, implantation of embryonic bovine thymus grafts was performed in tumour transplanted nude mice. When these grafts were accepted, tumours were also rejected. Possible mechanisms of reconstitution and the reasons for the varying results are discussed.

Adenocarcinoma↗
PubMed2006

ABH histo-blood group antigens in human thymus involution.

BACKGROUND: Human histo-blood group antigens (HBGA) are genetically determined glycoproteins supposed to participate in cell differentiation, adhesion, cancer metastasis and angiogenesis. In tissues, HBGA are mostly expressed in epithelial cells (EC). The EC comprising the thymocyte microenvironment play an important role in the ontogeny of the thymus. The aim of the present work is to investigate ABH HBGA in senile thymus and to characterize their expression pattern related to the process of aging. METHODS: Routine histology and immunohistochemical techniques were applied on thymus glands from senile and young individuals. RESULTS: Involuted thymus exhibited large areas of adipose tissue containing scattered EC, all positive for HBGA. Stromal EC revealed different morphology and intrathymic localization but uniform cytoplasmic staining for ABH antigens. Endothelial cells of blood vessels and red blood cells were intensely stained for HBGA. Only single scattered lymphocytes possessed HBGA. In contrast with senile thymus, most lymphocyte populations in the gland of young individuals, as well as the Hassall's corpuscules, expressed HBGA. CONCLUSIONS: The epithelial framework reorganization during age-related thymus involution involves modulation in ABH antigen expression in EC. These molecules are required by thymic EC to maintain the reduced but important crosstalk with lymphocytes during involution. The diminished reactivity for ABH antigens in the lymphocytes of aged thymus might reflect the impaired communication between these two cell types. We present novel evidence for permanent presence and modulation of ABH antigen reactivity in senile thymus, supporting the view that these molecules might be developmentally regulated.

ABO Blood-Group System↗
PubMed1994

The thymus of the guinea fowl from the eighteenth day of incubation until maturity.

The thymus gland of the guinea fowl appeared as a series of pink, irregular-shaped lobes along the jugular veins. These lobes were 13 in number with seven on the right and six on the left side. The third and sixth lobes on the right side were the largest. The largest lobe measured about 20.0 x 5.0 mm while the smallest measured about 5.0 x 4.0 mm. Histologically, it was encircled by a thin layer of poorly stained connective tissue from which strands penetrated the thymic tissue giving incomplete lobules peripherally as early as day 18 of incubation. Lymphocytes and reticular epithelial cells were the two types of cells occurring at this time. Reticular epithelial cells were observed to be vacuolated especially towards the centre of the gland. Macrophages were observed in the thymus on day 20 of incubation for the first time. The blood vessels had accompanied the interlobular septa into the thymus. By day 21 of incubation, blood vessels had actually penetrated the thymic tissue but most of these vessels were of the capillary size. The cortex also became quite distinct from the medulla. At day 22, vacuolation ceased to appear in the cells at the cortical zone. Macrophages were still less than 10 in the slide. At day 23, most blood vessels were within the medulla and they displayed compressed lumina. Mitotic figures became a common site amongst the large lymphocytes and reticular epithelial cells. By day one post-hatch, lobulation of the thymus was still poor and macrophages became difficult to identify. The small and medium lymphocytes had outnumbered the large lymphocytes throughout the thymic tissue except at the most peripheral zone of the cortex. Fine vacuoles had reappeared within the cytoplasm of the reticular epithelial cells in the cortex. By day five, the distribution of blood vessels was almost uniform between the cortex and medulla. At three weeks post-hatch, plasma cells and red blood cells were seen in the stroma of the gland for the first time and most of the red blood cells occurred in the medulla.

Animals↗
PubMed1986

Effect of corticosteroids on the thymus of the fish Oryzias latipes.

Morphology and development of the thymus in fish Oryzias latipes was studied in response to corticosteroids. Adult fish were subjected to different concentrations of two corticosteroids, deoxycorticosterone acetate (DOCA) and cortisone acetate (CA). Histology of the thymus and thymocyte counts in treated fish were compared to normal ones. There was no change in histology of thymus due to CA treatment even those subjected to 10 mg/l water which is a lethal dose of DOCA. In contrast, the effect of DOCA at low doses (0.01 and 0.1 mg/l water) was examined and resulted in reduction of thymus volume due to depopulation of thymocytes from the entire gland. Thymus subjected to DOCA at a high dose (1 mg/l water) caused destruction of all thymocytes and reticular cells resulting in complete disappearance of the thymus. There was dose dependent mortality associated with DOCA. The maximum lethal dose was 10 mg/l causing death of all treated fish within a few hours. This information is relevant to the use of CS in fish therapy in response to stress.

Aging↗
PubMedDate not supplied

The immune-endocrine loop during aging: role of growth hormone and insulin-like growth factor-I.

Why a primary lymphoid organ such as the thymus involutes during aging remains a fundamental question in immunology. Aging is associated with a decrease in plasma growth hormone (somatotropin) and IGF-I, and this somatopause of aging suggests a connection between the neuroendocrine and immune systems. Several investigators have demonstrated that treatment with either growth hormone or IGF-I restores architecture of the involuted thymus gland by reversing the loss of immature cortical thymocytes and preventing the decline in thymulin synthesis that occurs in old or GH-deficient animals and humans. The proliferation, differentiation and functions of other components of the immune system, including T and B cells, macrophages and neutrophils, also demonstrate age-associated decrements that can be restored by IGF-I. Knowledge of the mechanism by which cytokines and hormones influence hematopoietic cells is critical to improving the health of aged individuals. Our laboratory has recently demonstrated that IGF-I prevents apoptosis in promyeloid cells, which subsequently permits these cells to differentiate into neutrophils. We also demonstrated that IL-4 acts much like IGF-I to promote survival of promyeloid cells and to activate the enzyme phosphatidylinositol 3'-kinase (PI 3-kinase). However, the receptors for IGF-I and IL-4 are completely different, with the intracellular beta chains of the IGF receptor possessing intrinsic tyrosine kinase activity and the alpha and gammac subunit of the heterodimeric IL-4 receptor utilizing the Janus kinase family of nonreceptor protein kinases to tyrosine phosphorylate downstream targets. Both receptors share many of the components of the PI 3-kinase signal transduction pathway, converging at the level of insulin receptor substrate-1 or insulin receptor subtrate-2 (formally known as 4PS, or IL-4 Phosphorylated Substrate). Our investigations with IGF-I and IL-4 suggest that PI 3-kinase inhibits apoptosis by maintaining high levels of the anti-apoptotic protein Bcl-2. The sharing of common activation molecules, despite vastly different protein structures of their receptors, forms a molecular explanation for the possibility of cross talk between IL-4 and IGF-I in regulating many of the events associated with hematopoietic differentiation, proliferation and survival.

Aging↗
PubMed2002

Age-associated loss of bone marrow hematopoietic cells is reversed by GH and accompanies thymic reconstitution.

Deterioration of the thymus gland during aging is accompanied by a reduction in plasma GH. Here we report gross and microscopic results from 24-month-old Wistar-Furth rats treated with rat GH derived from syngeneic GH3 cells or with recombinant human GH. Histological evaluation of aged rats treated with either rat or human GH displayed clear morphologic evidence of thymic regeneration, reconstitution of hematopoietic cells in the bone marrow, and multiorgan extramedullary hematopoiesis. Quantitative evaluation of formalin-fixed, hematoxylin and eosin-stained sections of bone marrow from aged rats revealed at least a 50% reduction in the number hematopoietic bone marrow cells, compared with that of young 3-month-old rats. This age-associated decline in bone marrow leukocytes, as well as the increase in bone marrow adipocytes, was significantly reversed by in vivo treatment with GH. Restoration of bone marrow cellularity was caused primarily by erythrocytic and granulocytic cells, but all cell lineages were represented and their proportions were similar to those in aged control rats. On a per-cell basis, GH treatment in vivo significantly increased the number of in vitro myeloid colony forming units in both bone marrow and spleen. Morphological evidence of enhanced extramedullary hematopoiesis was observed in the spleen, liver, and adrenal glands from animals treated with GH. These results confirm that GH prevents thymic aging. Furthermore, these data significantly extend earlier findings by establishing that GH dramatically promotes reconstitution of another primary hematopoietic tissue by reversing the accumulation of bone marrow adipocytes and by restoring the number of bone marrow myeloid cells of both the erythrocytic and granulocytic lineages.

Aging↗
PubMed1999

Early differentiation of thymic dendritic cells in the absence of glucocorticoids.

The possible role of glucocorticoids (GCs) in the maturation of thymic dendritic cells (DCs) during early ontogeny was analyzed in the progeny of adrenalectomized pregnant rats (Adx foetuses). This experimental model ensured the lack of GCs until establishment of foetal hypothalamus-pituitary gland-adrenal (HPA) axis, and showed profound modifications of the development of thymus gland. In the absence of maternal GCs, there was a high percentage of DCs, many of them exhibiting a mature phenotype, in the 15-16 day-old Adx foetal thymus, which sharply decreased to reach control values on foetal day 17. On the other hand, the absolute number of DCs of Sham foetal rats increased throughout ontogeny, whereas the high numbers found in 15-16 day-old Adx foetuses significantly diminished in the following days. This process was closely correlated with the thymocyte life span, previously demonstrated, and the early appearance of DCs in the spleen. Our results demonstrate that like for other cell components of rat thymus, DC maturation is accelerated in an early foetal microenvironment devoid of glucocorticoids.

Adrenalectomy↗
PubMed1984

Sebaceous glands within the thymus: report of three cases.

Sebaceous glands in the thymus were discovered in three patients--two with myasthenia gravis and the other, who was operated on because of aortic valvular disease--with an unsuspected thymoma. Sebaceous glands not associated with hair follicles occur in diverse sites, the majority of which are in the head and neck or anogenital regions. Although most of these sites arise from the ectoderm, sebaceous glands have been reported in a thyroglossal duct, the larynx, and the esophagus, which are entodermal structures. Thus, precedents for ectodermally derived sebaceous glands in endodermal sites exist, but sebaceous glands have not previously been reported in the thymus. The authors speculate that their occurrence in the thymus may be related to the reported ectodermal contribution to the developing thymus by the epibranchial placode or cervical sinus.

Adult↗
PubMed1981

Myasthenia gravis. A survey.

Myasthenia gravis is a chronic disease characterized by a fluctuating weakness of voluntary muscle, with a preference for the muscles innervated by cranial nerves. The pathophysiological mechanism is a loss of postsynaptic acetylcholine receptors to less than 20-30% so that the safety margin of neuromuscular transmission is lost. It is probable that the function of the remaining acetylcholine receptors is impaired by antibodies against receptor proteïn, which can be demonstrated in the serum in 80-90% of the patients, and which are highly specific for the disease. An experimental autoimmune myasthenia can be induced in many animal species by immunization with purified receptor proteïn and this disease is remarkably similar to the human myasthenia with exception of the fluctuating course. The human disease has to be considered as an autoimmune disease, although the initiating mechanism is unknown. The occurrence of tumors of the thymus in 10-15% and the presence of germinal centres in about 70% of the thymus glands removed by operation are highly suggestive of the importance of the thymus in the pathogenesis, but the definite mechanism (harbouring of an abnormal antigen in myoid cells, or/and false instruction of thymocytes with lack of suppressor cells) is essentially unknown. In most patients the disease tends ot have a favourable course from 5-10 years after onset and complete remission occur in about 20% after 10-20 years. Therapy with anticholinesterases, providing an increase in acetylcholine, is of partial benefit in most patients. Thymectomy has an excellent effect in about 30% of the patients without thymoma under the age of 40 during the first three years of the disease, and is of benefit in still another 30-40%. The use of prednisone and immuno-suppressive drugs has improved the prognosis of the 20% of the patients with severe life threatening symptoms, half of whom have a thymoma.

Acetylcholinesterase↗