A prospective randomized comparison of sequential versus monoculture systems for in-vitro human blastocyst development.

BACKGROUND: Extending the period of in-vitro culture to the blastocyst stage may improve implantation rates in IVF treatment. Recognition of the dynamic nature of early embryo metabolism has led to the development of commercially available sequential culture systems. However, their improved efficacy over monoculture systems remains to be demonstrated in prospective studies. METHODS: Embryos obtained from 158 women undergoing IVF treatment were randomized by sealed envelopes to culture in one of three systems: (A) culture for 5 days in our own monoculture medium (Rotterdam medium); (B) culture for 3 days in Rotterdam medium followed by 2 days in fresh Rotterdam medium; (C) culture for 5 days using the commercially available G1/G2 sequential culture system. RESULTS: There were no significant differences in blastulation, implantation or pregnancy rates between the three tested culture systems. CONCLUSION: The employed monoculture system is as effective as the G1/G2 sequential system for the culture of blastocysts for IVF.

Pre-autoimmune thyroid abnormalities in the biobreeding diabetes-prone (BB-DP) rat: a possible relation with the intrathyroid accumulation of dendritic cells and the initiation of the thyroid autoimmune response.

Thyroid autoimmune reactions start with an accumulation of mainly dendritic cells in the thyroid. There is increasing evidence that, apart from being antigen-presenting cells, they are also able to control the growth and hormone synthesis of neighbouring endocrine cells. The questions thus arise: are dendritic cells accumulating in the pre-autoimmune thyroid in response to an altered proliferative or metabolic activity of thyrocytes, and do cytokines, monocyte chemoattractants, or both, have a role in their accumulation? We have investigated these questions in thyrocytes of the biobreeding diabetes-prone (BB-DP) rat in relation to the start of the intrathyroid accumulation of dendritic cells--that is, at about 9 weeks of age. BB-DP rats and Wistar rats (controls) were studied from 3 to 20 weeks of age. Hyperplastic goitre development was studied by assessing the thyroid weight and by measuring the number of thyrocyte nuclei per 0.01 mm2 thyroid section. In addition, the in situ expression of interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-alpha), monocyte-chemotactic protein-1 (MCP-1), and intercellular adhesion molecule-1 (ICAM-1) were studied by immunohistochemistry. The in vitro proliferative capacity of BB-DP and Wistar thyrocytes was measured by tritiated-thymidine ([3H]TdR) and bromodeoxyuridine (BrdU) incorporation into reconstituted, TSH- and non-TSH-stimulated, cultured thyroid follicles. Further in vitro studies consisted of measurement of the production of thyroxine (T4), triiodothyronine (T3), thyroglobulin, IL-6, TNF-alpha and MCP-1 by the thyroid follicles. BB-DP rats developed a small hyperplastic goitre between the ages of 9 and 12 weeks. The in vitro proliferative rate of thyrocytes isolated from hyperplastic BB-DP thyroids was significantly lower than that of Wistar thyrocytes. This phenomenon also occurred in follicles isolated from BB-DP rats before hyperplastic goitre development, which produced significantly less T4, but more T3, than did Wistar follicles of the same age. At the time of and after hyperplastic goitre development, BB-DP follicles exhibited altered metabolic behaviour and produced significantly more T4, but equal amounts of T3 compared with both Wistar follicles of the same age and follicles of younger BB-DP rats (both under basal conditions and TSH-stimulated). In vitro IL-6 production by these BB-DP thyroid follicles was also increased. There was no noteworthy difference in production of thyroglobulin and MCP-1 between BB-DP and Wistar follicles at any age. TNF-alpha was not produced by BB-DP or Wistar thyroid follicles. Immunohistochemistry revealed the expression of IL-6 by both BB-DP and Wistar thyroid follicle cells at all times of sampling. MCP-1 and TNF-alpha were expressed only when infiltrates were present in BB-DP thyroids (restricted to leucocytes, ages > 18 weeks). Modest ICAM-1 expression was restricted to large blood vessels in both BB-DP and Wistar thyroids; in the case of infiltrates (BB-DP rat) alone, high ICAM-1 expression was found on blood vessels and leucocytes in these infiltrations. At the time of intrathyroidal dendritic cells accumulation, BB-DP rats develop a small hyperplastic goitre. At that time there is also in vitro evidence for a shift to a higher production of thyroxine and IL-6 from thyrocyte follicles. The in vitro proliferation rate of BB-DP thyrocytes is, however, abnormally low (both in the pre- and hyperplastic period). Similar pre-autoimmune thyroid growth abnormalities have been described in another animal model of thyroid autoimmune disease, the obese strain chicken.

A population of interstitial cells in the anterior pituitary with a hematopoietic origin and a rapid turnover: a relationship with folliculo-stellate cells?

The non-hormone secreting folliculo-stellate (FS) cells in the anterior pituitary (AP) appear heterogeneous. Some of these cells have been described as having a neuroectodermal origin and being glial, while some others have been suggested to be monocytic or dendritic cells (DC). We have analyzed here the hematopoietic origin of interstitial cell populations in the AP. In the rat AP, the relative densities of S100+ FS cells and major histocompatibility complex (MHC) class II-expressing DC-like cells show a parallel increase in the postnatal period between the age of 3 weeks to 2 months. We first looked for the presence of donor derived cells in the AP of lethally irradiated bone marrow (BM)-transplanted rats. Donor derived myeloid cells carrying the n haplotype of the MHC class I antigen (RT1.An) reacting with the OX27 moAb, could not be detected in the AP three months after transplantation. It appeared, however, that OX27+ DC-like cells a-priori were virtually absent from the rat AP. Therefore this transplantation model was not suitable for our studies. We then turned to a model of transgenic mice expressing a suicide gene in subpopulations of dendritic cells. Mice were lethally irradiated and received a BM transplant from the transgenic animals, with or without a treatment with ganciclovir (GCV) that specifically kills the dividing cells expressing the suicide gene. This model has already been used to identify and delete mainly dendritic cell populations, viz N418+ and ER-BMDM1+ dendritic cells in the marginal zones of the spleen and in the thymic medulla. We observed in the AP a 30% reduction of the ER-BMDM1+ FS-like cells and a 50-100% reduction of interstitial cells expressing the F4/80, Mac-1 and MOMA-1 markers in the mice receiving the transgenic BM and treated with GCV, compared to control mice that were not treated with GCV or that received non-transgenic BM. When a treatment with granulocyte-macrophage colony-stimulating factor (GM-CSF) was initiated during the GCV treatment, we observed an even stronger reduction of the above-mentioned interstitial cell populations. These data indicate that in the mouse AP a population of stellate cells exists with a hematopoietic origin, that expresses markers of myeloid cells, and that has a rapid turnover.

Heterogeneity of pituitary folliculo-stellate cells: implications for interleukin-6 production and accessory function in vitro.

The population of folliculo-stellate (FS) cells of the rat anterior pituitary has been shown to be ultrastructurally and immunohistochemically heterogeneous. Based on the overlap of ultrastructural characteristics, the localization in the anterior pituitary and the co-expression within the same cel of the S-100 protein (a marker for FS cells) and MHC-class II determinants (an immune marker) we concluded that a partial overlap exists between the population of FS cells and the monocyte-derived dendritic cells (DC). In this report we describe that interleukin-6 (IL-6) immunoreactivity was found in situ in stellate cells of the rat, mouse and human anterior pituitary at a very low density (< 1% of the cells); the topography was reminiscent of the distribution of FS cells. In the present study we also analyse three different pituitary cell separation methods, in order to study the functional heterogeneity of the FS cells in vitro, and to verify whether functionally distinct subpopulations exist within the FS cell group. Production of bioactive IL-6 was measured in conditioned media of rat anterior pituitary cells separated by (i) bovine serum albumin (BSA) gradient sedimentation at 1 g, (ii) Nycodenz gradient and (iii) a magnetic cell separation (MACS) technique. Production of bioactive IL-6 by cell cultures of 1 to 4 days was correlated with the proportional number of S100 immunoreactive and S100 producing cells, but was not correlated with the proportional number of MHC-class II expressing (OX6-positive) dendritic cells (DC). The distribution pattern of OX6-positive DC was found to partly overlap with the distribution pattern of S100-positive cells in the BSA gradient. Co-sedimentation of S100-positive FS cells and MHC-class II-expressing DC was not restricted to the top fractions of the BSA gradient, but was also found in the low density Nycodenz fraction. MACS separation of the rat anterior pituitary cells resulted into a population enriched in OX6 and OX62 positive DC and a population devoid of such cells, while S100+ cells were equally divided into these two subpopulations. Although there was a significantly decreased production of IL-6 as compared to that of an original pituitary cell population, both MACS separated populations were equal in IL-6 production. The diminution in IL-6 production in both populations may be the result of an impediment of paracrine communication due to the MACS separation into these two populations. Our data also show that a subpopulation of FS cells was capable of stimulating T cell proliferation in vitro. Concomitantly with the distribution pattern of S100- and OX6-immunoreactive cells in the BSA and Nycodenz gradient fractions, we found a similar pattern of stimulation of T cell proliferation. Unlike the IL-6 production pattern, the T cell stimulating capacity was present in the MHC-class II-enriched cell population but absent in the MHC-class II-depleted cell population. These findings-together with earlier in situ histochemical data-suggest that there is an OX6+ S100- subpopulation of FS cells in the anterior pituitary that in itself is capable of stimulating T cell proliferation in vitro, and acts as lymphoid DC. There is also an S100+ OX6- population that is unable to stimulate T cell proliferation in vitro. Both populations are able to produce IL-6, but probably need stimuli from other subpopulations of pituitary cells (or exogeneous stimuli) to produce maximal amounts of IL-6.

Immunohistochemical, morphological and ultrastructural resemblance between dendritic cells and folliculo-stellate cells in normal human and rat anterior pituitaries.

Immunolabeling of cryo-sections of human anterior pituitaries obtained at autopsy, and of cryo-sections of freshly prepared rat anterior pituitaries, with a panel of monoclonal antibodies against markers of the monocyte/dendritic cell/macrophage lineage, reveals in both species a characteristic pattern of immunopositive cells, among which many cells with dendritic phenotype are found. Cells characterized by marker expression of MHC-class II determinants and a dendritic morphology are present in both human and rat anterior pituitary. Markers characteristic of dendritic cells such as the L25 antigen and the OX62 antigen were present in anterior pituitaries from human and rat respectively. The population of MHC-class II expressing dendritic cells of the rat anterior pituitary is compared at the ultrastructural level with the folliculo-stellate cell population, which cell type has been previously characterized by its distinctive ultrastructure and immunopositivity for the S100 protein. Using immuno-electron microscopy of rat anterior pituitaries fixed with periodate-lysine-paraformaldehyde, we were able to distinguish non-granulated cells expressing MHC-class II determinants, whereas no MHC-class II expression was found in the granulated endocrine cells. Using double immunolabeling of cryo-sections of these rat AP with 25 nm and 15 nm gold labels, we demonstrated an overlap between the populations of MHC-class II-expressing and S100 protein-expressing cells. Furthermore, MHC-class II-expressing and S100-positive cells showed ultrastructural characteristics that have been previously ascribed to folliculo-stellate cells. At the light microscopical level in the rat AP, a proportion of 10 to 20% of the S100-positive cells was found immunopositive for the MHC-class II marker OX6. In the human AP, S100-positive folliculo-stellate cells and cells expressing the leukocyte common antigen CD45 were found to occupy predominantly different tissue compartments in the human anterior pituitary, namely the epithelial parenchyme cords and perivascular compartments respectively. A proportion of CD45+ cells was found in the parenchyme compartment and, vice versa, indicating an overlap of the tissue compartments in which both cell types occur. However, at the light microscopical level we could not find cells expressing both the S100 and CD45 marker. The present finding of a proportion of S100-positive pituitary cells with ultrastructural and immunohistochemical characteristics of both dendritic cells and folliculo-stellate cells, confirms the suggested heterogeneity of the latter cell group with respect to their ultrastructural phenotype and putative function. The possibility of a myeloid origin of part of the folliculo-stellate cell group in the AP, is discussed and might elucidate some of the discrepancies in the literature concerning the embryological origin of this cell group.

Further studies on the regulation, localization and function of the TRH-like peptide pyroglutamyl-glutamyl-prolineamide in the rat anterior pituitary gland.

Recent evidence shows that thyrotrophin-releasing hormone (TRH) immunoreactivity in the rat anterior pituitary gland is accounted for by the TRH-like tripeptide pyroglutamyl-glutamyl-prolineamide (pGlu-Glu-ProNH2, < EEP-NH2). The present study was undertaken to investigate further the regulation, localization and possible intrapituitary function of < EEP-NH2. Anterior pituitary levels of < EEP-NH2 were determined between days 5 and 35 of life, during the oestrous cycle and after treatment with the luteinizing hormone-releasing hormone (LHRH) antagonist Org 30276. Treatment of adult males with the LHRH antagonist either for 1 day (500 micrograms/100 g body weight) or for 5 days (50 micrograms/100 g body weight) reduced anterior pituitary < EEP-NH2 levels by 25-30% (P < 0.05 versus saline-treated controls). Anterior pituitary < EEP-NH2 increased between days 5 and 35 of life. In females, these levels were 2- to 3-fold higher (P < 0.05) than in males between days 15 and 25 after birth; these changes corresponded with the higher plasma follicle-stimulating hormone (FSH) levels in the female rats. After day 25, < EEP-NH2 levels in female rats decreased in parallel with a decrease in plasma FSH. Injections with the LHRH antagonist (500 micrograms/100 g body weight), starting on day 22 of life, led to reduced contents of < EEP-NH2 in the anterior pituitary gland of female rats on days 26 and 30 (55 and 35% decrease respectively). Levels of < EEP-NH2 in the anterior pituitary gland did not change significantly during the oestrous cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of folliculo-stellate cells on biphasic luteinizing hormone secretion response to gonadotropin-releasing hormone in rat pituitary cell aggregates.

Anterior pituitary cells cultured as three-dimensional cell aggregates and incubated with gonadotropin-releasing hormone (GnRH) show a biphasic pattern of luteinizing hormone (LH) release when steroid-free bovine follicle fluid is added to the culture medium. Initially, the GnRH-induced LH release is low (lag-phase response), but LH release increases during further incubations with GnRH (primed-state response). Also, in aggregates of dispersed cells from long-term ovariectomized rats cultured for 2 days in the presence of 1% bovine follicle fluid, a low initial LH responsiveness to GnRH could be restored. Cycloheximide was found to block the induction of the primed state, indicating the protein synthesis dependency of GnRH self-priming. In aggregates from gonadotroph-enriched cell populations obtained by velocity sedimentation in a bovine serum albumin gradient, addition of 1% bovine follicle fluid to the culture medium also restored a biphasic pattern of GnRH-induced LH release. However, co-culturing the gonadotroph-enriched cell aggregates with a folliculo-stellate (FS) cell-enriched population resulted in the attenuation of the differences in LH secretion rate between early and late responses to GnRH. The present example of the attenuation by folliculo-stellate cells of pituitary hormone secretion responses demonstrates that the cells regulate the cellular processes leading to a priming of the LH response to GnRH, rather than interfering with the access of GnRH to its receptor in gonadotrophs. Finally, it was found that stimulation of the adenylate cyclase enzyme with maximal effective doses of forskolin counteracted the inhibitory effect of bovine follicle fluid on the initial LH response to GnRH, but did not completely abolish the biphasic pattern of LH release. It is concluded that coupling to the adenylate cyclase enzyme is presumably involved in the LH surge inhibiting feedback action on the pituitary cells, but also other messenger pathways and intercellular interactions between pituitary cells may play a role in establishing a biphasic LH release at the pituitary level following GnRH administration.

An immunohistochemical study on organized lymphoid cell infiltrates in fetal and neonatal pancreases. A comparison with similar infiltrates found in the pancreas of a diabetic infant.

Lymphoid cell infiltrates were analyzed using immunohistochemical techniques on 5 normal fetal and 6 normal neonatal pancreases. Data were compared to data obtained analyzing the lymphoid cell infiltrates in the pancreas of an 8 months old diabetic infant. In the normal fetal and neonatal pancreases islets were intact and not infiltrated. In the diabetic infant beta-cells had vanished in almost all islets, the remaining islets showed a minor infiltration with primarily T-cells, a few B-cells, and some classical macrophages. It appeared that a widespread infiltration of the exocrine pancreas with single dendritic-like cells, and T-cells, and little clusters of these cells were normal features of fetal and neonatal pancreases. In the diabetic case these infiltrative patterns were more pronounced. Larger accumulations of such lymphoid cells could also be detected in the normal fetal and neonatal pancreases and these consisted mainly of T-cell zones, sometimes containing HEV's, with intermingled interdigitating dendritic cells and a few macrophages. This architecture is reminiscent of peripheral lymphoid tissue, such as bronchus-or gut-associated lymphoid tissue. The function of this fetal/neonatal intrapancreatic lymphoid tissue (which disappears in later life) is unknown. Various possibilities are suggested such as a yet unknown ubiquitous fetal/neonatal microbial infection, tolerance induction towards islet cell antigens, an endocrine regulatory function of infiltrated lymphoid cells, and a normal ontogenetic process.

Morphological, immunohistochemical and functional homologies between pituitary folliculo-stellate cells and lymphoid dendritic cells.

Lymphoid dendritic cells and pituitary folliculo-stellate cells have many morphological and immunocytochemical characteristics in common. They both have a stellate morphology, they are specifically detected by the presence of MHC class II determinants as well as the Ca(2+)-binding protein S100, they also produce the cytokine interleukin 6. A panel of monoclonal antibodies directed against murine and rat macrophages and/or dendritic cells was used to study the presence of dendritic and folliculo-stellate cells in the mouse and rat anterior pituitary. In the mouse pituitary stellate cells are detected with a monoclonal antibody against the dendritic cell aminopeptidase, but these cells display no S100 protein immunoreactivity. In the rat pituitary there were many S100 protein positive folliculo-stellate cells as well as a few macrophage-like cells, whereas stellate cells that express MHC class II markers were found in both mouse and rat anterior pituitaries. The present data suggest of a homology between lymphoid dendritic cells and pituitary folliculo-stellate cells, or at least a subgroup of the latter cells.

A delayed-type hypersensitivity skin-test system using the insulinoma cell line RINm5F to monitor beta cell-specific cellular autoimmune reactivity in the spontaneously diabetic BB/O rat.

Islet-specific autoimmune reactivity (humoral and cell-mediated) is the basis for the insulitis process of type I diabetes mellitus. In this report a delayed-type hypersensitivity (DTH) skin test was used to monitor the presence of an islet-specific cell-mediated autoimmune component in BB/O rats. The BB/O rat is a strain characterized by the spontaneous development of type I diabetes. Intact RINm5F cells as well as a RINm5F cell membrane preparation were used as DTH skin test antigens. Rats of different ages and disease stages were tested in the ear with the insulinoma cell line and its cell membrane preparation. As control antigens, the fibroblast cell line 3Y1 and a cell membrane preparation made thereof were used. The DTH reaction system showed a positive cell-mediated reactivity in BB/O rats for membrane-bound RINm5F cell antigens, and not for the control fibroblast 3Y1 cell membrane determinants. The true DTH character of the skin test was established by the time-course of the reaction (maximum at 24 h), the histopathology (infiltration by dendritic cells, lymphocytes and macrophages), and the possibility to transfer the reaction with spleen cells and lymph node cells. The DTH test towards RINm5F cells showed the highest prevalence of positivity (100%) in BB/O rats around the onset of diabetes (3 weeks before to 3 weeks after the onset of glucosuria). The prevalence of DTH positivity was 56% in the period of more than 3 weeks before the onset of glucosuria. In BB/O rats with a duration of glucosuria of more than 3 weeks, the prevalence of positivity was around 60-70%.

Dendritic cells and class II MHC expression on thyrocytes during the autoimmune thyroid disease of the BB rat.

The BB rat is a well-established model for spontaneous thyroid autoimmune disease. Since antigen presentation in thyroid autoimmunity is still a matter of debate, we studied the presence of antigen-presenting dendritic cells in the thyroid of the BB/O rat during the development of the disease in relation to the presence of other leucocytes and the aberrant expression of class II MHC determinants by thyrocytes. Thyroid glands, as well as thyroid-draining lymph nodes, were investigated in enzyme histochemistry and immune histochemistry. The appearance of anti-colloid antibodies in the circulation at 6 weeks of age was accompanied by an increase in the weight of the thyroid-draining cervical lymph nodes, which contained many anti-thyroglobulin-producing plasma cells. The only noteworthy event in the thyroid gland in this early stage of the disease was an increase in the number of dendritic cells. T cells, B cells, and plasma cells were virtually absent from the thyroid, and thyrocytes were invariably negative for class II MHC determinants. Only after 18 weeks of age, when large accumulations of dendritic cells, B lymphocytes, and T lymphocytes were seen in 40% of the BB thyroids, could some class II MHC positive thyroicytes be observed. At this stage the thyroid also contained some anti-thyoglobulin-producing plasma cells. Our observations suggest that dendritic cells play a role in antigen presentation in the early stages of the thyroid autoimmune response.

Dendritic cells and scavenger macrophages in pancreatic islets of prediabetic BB rats.

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease whose notorious pathologic feature is insulitis accompanied by destruction of beta-cells. In this morphological study, we examined the pancreatic events during the onset of diabetes in spontaneously diabetic BB/Organon rats. Dendritic cells were the first cells to accumulate around the islets, followed by lymphocytes. Scavenger macrophages and MHC class II-positive beta-cells were only seen late in the disease. These observations suggest a role for antigen-presenting dendritic cells in the onset of the beta-cell-specific autoimmune reaction and emphasize the necessity to distinguish between the several monocyte-macrophage subtypes in studies on the pathogenesis of IDDM.

Immunoglobulins of patients with idiopathic Addison's disease block the in vitro action of adrenocorticotropin.

The presence of serum immunoglobulins (Ig) blocking ACTH-induced adrenal DNA synthesis and/or cortisol production was studied in 25 patients with idiopathic Addison's disease. For this purpose guinea pig adrenal segments kept in organ culture were exposed to ACTH and graded concentrations of patient IgG. After a 5-h culture period the cortisol present in the culture fluid was measured by RIA, and DNA synthesis in the adrenal cells was measured using Feulgen densitometry on frozen sections of the cultured adrenal segments. Addition of ACTH alone in concentrations of 0.1-10 pmol/L to the culture system stimulated in vitro cortisol secretion; the maximal stimulation was 63 +/- 35% (+/- SD; n = 5) at a concentration 0.1 pmol/L. ACTH also increased (in concentrations of 1 fmol/L to 1 pmol/L) the percentage of fasciculata cells in S-phase from 0-4% (nonstimulated) to 5-12%. IgG preparations from all but 2 of the 25 patients with idiopathic Addison's disease blocked these in vitro ACTH-induced adrenal responses in a dose-dependent fashion. IgG from 2 patients with tuberculous adrenalitis, 1 patient with secondary adrenal insufficiency, and 7 normal subjects had no blocking activity. Among 5 non-Addisonian autoimmune endocrinopathy patients who had adrenal cytoplasmic autoantibodies, 4 had no ACTH-blocking IgGs. Two of 9 patients with miscellaneous adrenal disorders (Cushing's disease, pigmented adrenal micronodular dysplasia, and adrenal nodules) had ACTH-blocking activity. These results demonstrate the existence of IgGs blocking the in vitro effects of ACTH and suggest their involvement in the pathogenesis of idiopathic Addison's disease.

The goitre of the BB/O rat: an animal-model for studying the role of immunoglobulins stimulating growth of thyroid cells.

The BB rat is a well-known animal model for the study of autoimmune thyroid disease. Antithyroglobulin antibodies can be detected in the circulation from the age of 6 weeks onwards, and accumulations of lymphoid cells occurs in the thyroid of up to 60% of animals at the age of 20 weeks and over. The rat, however, stays euthyroid, the thyroid is not destroyed, and hence the disease is not yet well characterized. The study reported here shows that the thyroid weights of 41% (40/97) BB rats were raised from week 6 onwards in comparison to those of Wistar controls. Morphologically, BB thyroids showed a strong similarity to the human disease entity 'colloid goitre', namely an active growth, high columnar epithelium, branching and budding of thyrocytes, no signs of thyroid destruction and in 42% of rats at the age of 22-26 weeks, a development of intrathyroidal lymphoid tissue. Plasma TSH was not significantly raised in the animals. For this reason the presence of immunoglobulins which stimulate the growth of thyroid cells (so-called TGI's) was determined in 12-16-week-old BB rats (n = 10) and in control Wistar rats (n = 10). At this time a significant difference could be recorded in thyroid weights between BB/O rats and Wistar controls (20.1 +/- 6.0 mg vs. 15.8 +/- 2.9 mg, respectively), even in the absence of any intrathyroidal lymphoid cell infiltration. Protein-A-Sepharose purified serum IgG of these animals was used to detect TGI-activity via the 'Feulgen Cytochemical Bioassay'. Of the BB/O rats, eight were clearly positive for TGI, all of the Wistar rats were negative. The data show that the autoimmune prone BB rat may thus serve as an animal model for euthyroid goitre associated with thyroid stimulating antibodies.

Immunoglobulins of patients with Cushing's syndrome due to pigmented adrenocortical micronodular dysplasia stimulate in vitro steroidogenesis.

The putative stimulation of adrenal steroid production by immunoglobulins (Igs) of five patients with pigmented adrenocortical micronodular dysplasia and clinical Cushing's syndrome was investigated. Ascorbate depletion, a process linked to steroid production, was measured by a cyto-chemical bioassay employing guinea pig adrenal explants in organ culture and exposed to IgG from the patients and normal subjects. We also measured cortisol production by these segments during a 5-h culture period using a RIA. For positive reference values we studied the effects of ACTH-(1-39), ACTH-(1-24), ACTH-(11-24), and ACTH-(18-39) on in vitro ascorbate depletion and cortisol production. Both ACTH-(1-39) and ACTH-(1-24) depleted ascorbate and stimulated cortisol production in adrenal cells. The dose-response kinetics of the peptides were bell-shaped; maximal responses were reached in both instances at 1 fmol/L to 10 pmol/L. In all tests, stimulation of in vitro cortisol production was paralleled by ascorbate depletion. ACTH-(18-39) also stimulated ascorbate depletion and cortisol production, but at one concentration only (100 fmol/L), and TSH and LH had no effect. Protein-A-Sepharose-purified IgG preparations of the five patients stimulated ascorbate depletion and/or cortisol production in a dose-dependent fashion; however, the responses occurred over a narrow concentration range (15-150 micrograms IgG/mL culture fluid). These observations support the hypothesis that the hypercortisolism of the syndrome of pigmented adrenocortical micronodular dysplasia is due to circulating Igs that stimulate adrenal steroidogenesis.

Effects of ACTH and ACTH fragments on DNA synthesis in guinea-pig adrenal segments kept in organ culture.

Stimulation of adrenal DNA synthesis by ACTH and its fragments ACTH (Synacthen) and ACTH was investigated. Synthesis of DNA was measured as the increase in the percentage of cells in S-phase (Feulgen densitometry) in guinea-pig adrenal explants kept in organ culture and exposed to the peptides for 5 h at 37 degrees C. ACTH and its C-terminal fragment ACTH (corticotrophin-like intermediate lobe peptide) were found to be potent stimulators of in-vitro adrenal DNA synthesis. The dose-response kinetics were biphasic and optimal responsiveness was reached in both instances at 1 fmol/1-10 pmol/1 (this biological effect of ACTH has hitherto not been described). The N-terminal fragment ACTH gave only minimal responses. Thyrotrophin and LH, tested as controls, did not induce adrenal DNA synthesis. Epidermal growth factor was a potent stimulator of adrenal DNA synthesis in vitro. Our data suggest a trophic action of the C-terminal part of the corticotrophic molecule. Clear trophic effects were also found for the N-terminal part of the pro-opiomelanocortin molecule N-POC (optimum 0.1 nmol/l) and N-POC(51-62) (optimum 0.1 pmol/l). The latter observations support earlier concepts that this part of the pro-opiomelanocortin molecule has a stimulatory effect on adrenal DNA synthesis.