Mutations of the GREAT gene cause cryptorchidism

In humans, failure of testicular descent (cryptorchidism) is one of the most frequent congenital malformations, affecting 1-3% of newborn boys. The clinical consequences of this abnormality are infertility in adulthood and a significantly increased risk of testicular malignancy. Recently, we described a mouse transgene insertional mutation, crsp, causing high intraabdominal cryptorchidism in homozygous males. A candidate gene Great (G-protein-coupled receptor affecting testis descent), was identified within the transgene integration site. Great encodes a seven-transmembrane receptor with a close similarity to the glycoprotein hormone receptors. The Great gene is highly expressed in the gubernaculum, the ligament that controls testicular movement during development, and therefore may be responsible for mediating hormonal signals that affect testicular descent. Here we show that genetic targeting of the Great gene in mice causes infertile bilateral intraabdominal cryptorchidism. The mutant gubernaculae fail to differentiate, indicating that the Great gene controls their development. Mutation screening of the human GREAT gene was performed using DHPLC analysis of the genomic DNA from 60 cryptorchid patients. Nucleotide variations in GREAT cDNA were found in both the patient and the control populations. A unique missense mutation (T222P) in the ectodomain of the GREAT receptor was identified in one of the patients. This mutant receptor fails to respond to ligand stimulation, implicating the GREAT gene in the etiology in some cases of cryptorchidism in humans.     

Clonality Analysis of Benign Parathyroid Lesions by Human Androgen Receptor (HUMARA) Gene Assay

Benign conditions of the parathyroid gland have been classified as adenomas and hyperplasias. These entities however are difficult to distinguish when only a single gland is enlarged. Adenomas are defined as neoplastic clonal growths whereas hyperplasias are considered to be reactive processes of polyclonal origin. In order to analyze the clonal pattern of these lesions, we have studied hyperplasias and adenomas of parathyroid glands from women by the human androgen receptor (HUMARA) assay, a recently reliable and highly-lnformative technique based on the X-chromosome inactivation pattern in females. Samples consisted of formalin-fixed as well as frozen tissues. Informativeness with HUMARA marker was 87% (13/15 cases). All hyperplasias (5/5) and 6/8 adenomas yielded polyclonal results, since two alleles of similar intensity appeared when the lesion was HpaIl-digested. Two parathyroid adenomas had a loss of one X-alIeIe for the HUMARA gene and they were interpreted as monoclonal. These results show that parathyroid hyperplasias and adenomas, considered as multigland or monogland involvement diseases respectively, may be both polyclonal in origin, and that only a small subset of adenomas is found to be clonal. Consequently, clonality analysis cannot allow a clear distinction between these two entities as classically diagnosed. A different approach should be considering hyperplasia or adenoma when a polyclonal or monoclonal result has been obtained by clonality analysis.     

Papillary endothelial hyperplasia in the thyroid following fine-needle aspiration

A 74-year-old woman was found to have exuberant papillary endothelial hyperplasia within her thyroid gland subsequent to multiple fine-needle aspiration biopsies of a Hürthle cell neoplasm. To our knowledge, this histologic alteration in the thyroid has not been previously reported. We describe this unusual complication following fine-needle aspiration, and we delineate the clinicopathologic and differential diagnostic features.     

Lectin histochemistry on the dorsal epidermis of the Breton dog

Expression of sugar residues and the nature of oligosaccharide linkage during keratinocyte maturation in the epidermis of the Breton dog were studied with the use of lectin histochemistry. Thirteen lectins were used. Labelling was not observed with GSA I-B4, GSA II, UEA-I, and LTA. The cytoplasm of keratinocytes reacted with PNA, HPA, Con A, and WGA from the basal layer to the granular layer. PNA and Con A showed highest reactivity in the granular cell layer. The cell surface showed increased reactivity with PNA, HPA, and WGA with maturation of keratinocytes. KOH-neuraminidase treatment (KOH-Neu) increased PNA and RCA120 staining during keratinocyte differentiation thus indicating an increase in oligosaccharides terminating with sialic acid-Galbeta(1,3)GalNAc and sialic acid-Galbeta(1,4)GlcNAc, respectively. Labelling of the glycocalyx of basal and spinous keratinocytes with SNA and MAA revealed terminal Neu5acalpha(2,6)Gal/GalNAc and Neu5acalpha(2,3)Galbeta(1,4)GlcNAc. KOH-Neu-DBA showed oligosaccharides terminating with sialic acid-GalNAcalpha(1,3)GalNAc in the spinous and granular layers. A selective glycocalyx labelling of granular keratinocytes was observed with DBA and SBA. Reactions with MAA, PNA, DBA, RCA120, SBA, HPA, and WGA disappeared after the beta-elimination reaction. Our findings indicate that Breton dog epidermis contains more O-linked than N-linked oligosaccharides and confirm that different subpopulations of keratinocytes can be distinguished by lectin histochemistry.     

Patterns of basement membrane laminin distribution in nonneoplastic and neoplastic thyroid tissue.

Laminin, a major basement membrane component, is typically absent or partially lost around the epithelial elements of most invasive carcinomas. To evaluate the distribution of laminin in both primary and metastatic thyroid tumors, we studied 14 benign thyroid lesions (eight adenomas, two Graves' disease, two Hashimoto's thyroiditis, one adenomatous hyperplasia, one nodular goiter), 20 carcinomas (seven papillary, six tall cell variant, four follicular, three Hürthle), and eight metastases (five tall cell variant, three follicular) utilizing a polyclonal antibody against highly purified, nidogen-free laminin. All benign lesions showed positive, linear immunostaining along basement membranes. Partial loss or absence of laminin was seen in the solid areas of all types of thyroid carcinomas examined; well-differentiated papillary and follicular tumors, as well as papillary and follicular areas of more poorly differentiated neoplasms, maintained linear laminin immunostaining in the papillary cores beneath the epithelial cells and around follicles. A similar correlation between laminin deposition and architectural organization was seen in metastatic lesions. Hürthle cell carcinomas had a unique fragmented, pericellular immunostaining pattern around individual tumor cells, suggesting uncontrolled laminin synthesis. Our findings suggest that preservation of laminin production in thyroid tumors reflects their degree of differentiation and that absence of laminin correlates with lack of structural organization rather than reflecting invasive and metastatic potential.     

Completely allogeneic spleen cells induced cytolytic neonatal tolerance to alloantigens,but failed to establish allo-helper interactions with host T cells.

The injection of spleen cells from F1 mice into-newborns from a parental strain results in the establishment of cytolytic tolerance to donor alloantigens and the development of a lupus-like disease. This syndrome is the consequence of the recognition by alloreactive host CD4+ T cells of discordant major histocompatibility complex (MHC) class II antigens on semi-allogeneic donor B cells. We have analysed whether completely allogeneic spleen cells are as able as semi-allogeneic spleen cells to induce cytolytic tolerance to donor alloantigens and to co-operate with alloreactive T cells for autoantibody production. BALB/c mice were injected at birth with Thy-1-depleted spleen cells from (C57BL/6 x BALB/c)F1 or C57BL/6 mice, either alone or in combination. Cytolytic tolerance was always induced, as manifested by persistence of chimerism and acceptance of skin allografts. However, only F1 semi-allogeneic B cells were activated by alloreactive host T cells to produce anti-DNA IgG antibody. The deficient co-operation between BALB/c CD4+ T cells and completely allogeneic C57BL/6 B cells was confirmed after neonatal injection of (C57BL/ 6 x BALB/c)F1(Igha) spleen cells together with C57BL/6(Ighb) spleen cells. These mice developed anti-DNA antibodies bearing only the Igha allotype. Similar results were observed in experiments of allogeneic interaction in vitro, in which BALB/c CD4+ T cells were cocultured with either (C57BL/6 x BALB/c)F1 or C57BL/6 B cells. The present results demonstrate that completely allogeneic spleen cells efficiently induced cytolytic unresponsiveness to donor alloantigens, but B cells contained in this spleen cell population were unable to establish allo-helper interactions with alloreactive CD4+ T cells, suggesting that cytolytic and helper T-cell interactions involved in alloreactivity may be different.     

HLA-C revisited

During the past 10 years knowledge about the interactions between major histocompatibility complex (MHC) class I molecules and the T-cell receptor (TCR) complex of cytotoxic T-cells (CTL) has developed dramatically. But the primary interest, both with respect to structure as well as function, has concentrated on HLA-A and -B molecules because of their high sequence polymorphism and their dominating presence at the cell surface. In contrast, HLA-C molecules seemed to be of only minor importance in the cascade of immune reactions owing to their more limited polymorphism and reduced levels of surface expression. The inability to define a number of antigen specificities had the result that HLA-C molecules were often neglected in studies of immune response, transplantation, and disease association. More recently a new function has been identified for HLA class I molecules where they act as inhibitors of the lytic capacity of natural killer (NK) cells and non-MHC-restricted T-cells. Moreover, the understanding of this novel mode of negative regulation of cytotoxicity was remarkably influenced by HLA-C since these were the first HLA class I molecules found to have such inhibitory potential. With this new inhibitory function serving as an essential component of the immune system, HLA-C molecules can no longer be neglected.