Human natural killer cell activating receptors.

Natural killer (NK) cells were poorly characterized until 10 years ago and few molecules expressed on their cell surface were known. Now the situation has changed dramatically, since a plethora of receptors characterized by opposite functions have been functionally and molecularly defined. NK cells express clonally distributed inhibitory receptors specific for different groups of HLA class I alleles, thus protecting normal cells from NK-mediated lysis. On the contrary, various activating receptors are involved in triggering of NK-mediated natural cytotoxicity. Their engagement induces human NK cells to kill target cells that are either HLA class I-negative or -deficient. Here a brief description of the activating receptors and coreceptor and of their ligand(s) is given.

Involvement of natural cytotoxicity receptors in human natural killer cell-mediated lysis of neuroblastoma and glioblastoma cell lines.

The surface receptors involved in natural killer (NK) cell triggering during the process of target cell lysis have been at least in part identified. These are members of a novel family of receptors that has been termed natural cytotoxicity receptors (NCR). The first three members of this emerging group of receptors are the NKp46, NKp44 and NKp30 molecules that all belong to the immunoglobulin superfamily. Blocking of these receptors inhibits NK-mediated cytotoxicity against a wide variety of tumor target cells. In the present study, we show that these NCR are also involved in NK-mediated killing of tumor cells of neural origin. Glioblastoma and neuroblastoma target cells were efficiently killed by all NK clones analyzed since little protection from NK lysis was mediated by HLA class I molecules. Blocking of one or another NCR inhibited cytotoxicity; however, optimal inhibition was only observed when the three receptors were blocked simultaneously. A sharp difference in cytotoxicity against neural tumors was demonstrated between NCR(bright) and NCR(dull) NK clones, further supporting the notion that NCR play a critical role in the induction of cytotoxicity against tumor target cells of different histotype. Finally, our data also indicate that CD16 does not function as a triggering receptor involved in lysis of neural tumors since no difference in cytotoxicity could be substantiated between CD16(+) and CD16(-) NK clones and no correlation could be detected between the NCR(bright)/NCR(dull) phenotype and CD16 expression.

The human natural cytotoxicity receptors (NCR) that induce HLA class I-independent NK cell triggering.

The cytolytic activity mediated by human natural killer (NK) cells is the result of a balance between signals delivered by inhibitory and activating receptors. The inhibitory receptors are represented by different families of HLA-specific receptors characterized by immunoreceptor tyrosine-based inhibiting motif(ITIM) sequences in their cytoplasmic portion. The function and the specificity of the inhibitory receptors imply the existence of triggering receptors specific for non-HLA ligands that are responsible for the induction of the cytolytic activity against HLA class I-deficient target cells. These receptors have remained elusive until recently when three distinct NK-specific molecules, termed natural cytotoxicity receptors (NCR), were identified and cloned. The different members of this novel family of receptors play a complementary role in the recognition and lysis of target cells. The NCR family is composed by a heterogeneous group of molecules belonging to the Ig superfamily that associate to different immunoreceptor tyrosine-based activating motif (ITAM)-containing signal transducing polypeptides.

Triggering receptors involved in natural killer cell-mediated cytotoxicity against choriocarcinoma cell lines.

The lack of classical HLA-class I molecules on trophoblast is necessary to prevent allorecognition by maternal CTL, but may induce activation of NK cells. A protective role against NK cells equipped of suitable inhibitory receptors has been proposed for nonclassical HLA-class I molecules including HLA-E and HLA-G. In the present study we show that the NK-mediated killing of two choriocarcinoma cell lines, JAR and JEG3, is induced upon engagement of natural cytotoxicity receptors (NCR) with their specific ligands. In particular, we show that NKp44, a triggering receptor expressed at the NK cell surface only after in vitro culture in the presence of IL-2, plays a central role in triggering NK cytotoxicity against trophoblast cells. Also NKp46 appear to contribute to this function by cooperating with NKp44. On the other hand, other triggering receptors such as NKp30, 2B4, and NKG2D are not involved in killing of choriocarcinoma. Our findings suggest that resistance of trophoblast to NK-mediated cytotoxicity is the result of insufficient activating interactions between the various triggering NK receptors and their target cell ligands. On the other hand, the interaction of nonclassical HLA class I molecules with inhibitory NK receptors appears to play only a marginal role in regulating the susceptibility of choriocarcinoma to NK mediated cytotoxicity.

Immunofluorescent and ultrastructural analysis of plasma cell degeneration in the chicken Harder's gland.

In this study we describe some aspects of plasma cell degeneration in the chicken Harder's gland. The immunofluorescent patterns of cytoplasmic immunoglobulin (cIg) localization have been studied in relation to the ultrastructure of maturing and degenerating B cells. It appears that Russell body formation through the accumulation of Ig within the cisternae of the rough endoplasmic (RER) does not represent the only mechanism for the formation of cytoplasmic vacuoles. Mitochondrial swelling and disruption or dilation of Golgi cisternae, often preceding alterations of the RER, may be the origin of some vacuoles. It also appears that, in the Harder's gland, degeneration may occur not only in mature plasma cells but also in maturing B cells at a stage when only clusters of polyribosomes are found in the cytoplasm and no RER is yet developed. These observations are relevant to some immunofluorescence and ultrastructural patterns observed in human B-cell pathology.

Tumoral markers (CA 125--CEA) in the screening of ovarian cancer.

Ovarian cancer has high rate of mortality among malignant gynecologic tumors. Because of its aggressiveness and low rate of 5 year survival of patients treated, it is important to realise a screening program for its early diagnosis. Today, immunologic research is directed to the study of tumoral markers that allow us to detect the presence of still clinically silent ovarian neoplasms. Some tumoral markers such as CEA and CA 125 are available for post-surgical monitoring of patients treated for ovarian cancer. The Authors have carried out a study to evaluate the possibility of their use in the depistage of ovarian neoplastic pathology. A blood sample was taken for the evaluation of serum CEA and CA 125 in a series of 520 patients older than 45 years, who did not complain signs or symptoms of pelvic pathology. A pathologic value for CEA was considered higher than 7.3 ng/ml and for CA 125 greater than 37 U/ml. For CEA 2.5% (13 cases) presented pathologic values compared to 2.88% (15 cases) for CA 125. One third of cases (0.5%) with high levels of CEA had repeated blood samples. 3 of them had confirmed high levels of CEA but echotomography performed in these patients was negative for pathologic ovarian masses. 15 patients had CA 125 high levels. 3 out of 15 cases repeated the blood sample that resulted normal. On 11 of these cases an echotomography was also performed that diagnosed a uterine myomatosis in 4 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Frequency of cervico-vaginal infections (Trichomonas vaginalis; Chlamydia trachomatis -CHL-; herpes simplex virus -HSV-; human papilloma virus -HPV-) in cervical intraepithelial neoplasia.

The Authors have carried out a cyto-hystologic study on 533 cervical intraepithelial neoplasias (CIN) devoted to identifying the association frequency between cervical dysplastic lesions and cervico-vaginal infections caused by Trichomonas vaginalis, Chlamydia Trachomatis, Herpes Simplex virus and Human Papilloma virus. HPV lesions have revealed the pathology found more frequently in CIN lesions (33.2%) compared to 0.19% in the normal population, while the other infections have not shown significant differences between dysplastic lesions and normal control. In patients with CIN, the assumption of the estro-progestinic pill does not seem to contribute to the increase of frequency of cervico-vaginal infections.

Sonographic evaluation of ovarian volume in postmenopausal women: a screening test for ovarian cancer?

Ovarian cancer is the first cause of death from gynaecological malignancy. The poor over-all five year survival rate requires a specific procedure for early detection of ovarian carcinoma. An evaluation of ultrasonography as a screening test in early ovarian cancer is currently used in our Institute. A group of 500 volunteers without clinical symptoms, older than 45 years, and/or in postmenopausal period, were submitted to the procedure. We used a real-time mechanical sector scanner with 3 mHz transducer. The morphology and size of both ovaries were assessed. Abnormal results were obtained in 11 women. Four (4) postmenopausal patients underwent surgery. At the moment our study proves that ultrasonography is a valid procedure in the investigation of the ovaries in postmenopausal women. We need further evaluations to assess the real effectiveness of ultrasound examination as a screening test for early detection of ovarian cancer.

[The subfornical organ today: morphological aspects and functional role]. / L'organo subfornicale oggi: aspetti morfologici e ruolo funzionale.

The recognition of the role played by the subfornical organ (SFO) in the central regulation of body water balance has recently aroused new interest in this anatomical formation which remained ignored for a long time. The SFO is included in the group of the circumventricular organs. In higher vertebrates it is adherent to the ventral surface of the fornix and protrudes into the third ventricle at the level of the interventricular foramina, partially covered by the choroid plexus. The SFO appears as a small nodule, rounded or ovoidal in shape, consisting of highly vascularized nervous tissue and lined by ependyma at the ventricular surface. Its structural organization is fundamentally constant and presents only minor differences in the various species. The SFO neuronal perikarya show different aspects which have been classified in four types. However, it is not yet clearly defined if such aspects refer to distinct cell types or to different transitional features. Nerve and glial cell processes form a dense plexus through the SFO and the subependymal area, as well as in the connective tissue perivascular spaces. These may be narrow or wide and surround fenestrated and non-fenestrated capillaries, assuming sometimes a labyrinthine aspect. The ependymal lining of the SFO ventricular surface shows large variations and regional differences concerning the cell height, the number and development of microvilli, the cilia distribution. The structural properties of SFO, which is characterized by a rich and highly permeable capillary bed, by a wide surface area of contact and exchange with the cerebrospinal fluid, by direct and indirect neural connections with a number of regulatory structures, have been considered as the basis for the role of neurohumoral integration that SFO plays in regulating physiological and behavioral responses to water-mineral changes. Much experimental evidence substantiates this function. However, the studies on SFO are increasingly enriching the literature with new experimental, especially physiological and cytochemical, data which may suggest for this organ connections even more extensive and functions even more complex than those until now ascertained.

[Bone metastasis of leiomyosarcoma. Apropos of a case]. / Métastase osseuse d'un leiomyosarcome. A propos d'un cas.

INTRODUCTION: Bone leiomyosarcoma is a rare tumor, whether it may be primary or secondary. The authors report on the case of a woman, aged 67, admitted in January 1992 complaining of pain in the left hip and the upper end of the femur. CASE REPORT: In 1985 the patient underwent surgical excision of a soft tissue tumor in the right thigh, histologically diagnosed as a benign fibrous tumor. This lesion recurred locally four times and repeated excisions were performed throughout the years, always with a histological diagnosis of a benign lesion. On admission to hospital, the physical examination as well as laboratory data and plain roentgenograms were unremarkable. Both tomography and MRI showed a lesion in the upper end of the left femur. An isotopic bone scan showed marked increased uptake in the left hip extending to the femoral diaphysis. An open biopsy was performed for histology, immunohistochemistry and electron microscopy. A diagnosis of metastatic leiomyosarcoma was made. The retrospective histological examination of specimens of the soft tissue tumor excised in 1985 showed the same immunohistochemical features of the contralateral leiomyosarcoma. On this basis, one stage resection of the left hip and the upper end of the femur was performed and a Kotz modular prosthesis was inserted. Postoperative healing was achieved without any complications and the function of the operated limb was satisfactory. Three months after the operation pulmonary lesions were noted on chest radiographs and CT scan. The patient died two years after the first admission for widespread metastasis. DISCUSSION: In the reported case, the bony metastasis appeared to be the presenting finding of the soft tissue tumor of the contralateral thigh. This presentation is rare in previously published series. The misdiagnosis of the primary tumor had caused local recurrences, and an increased malignity occurred. According to the literature, a soft tissue leiomyosarcoma can be easily confused with other spindle cell lesions. Therefore an accurate histological and ultrastructural diagnosis is necessary for adequate surgical treatment.

[Histochemical aspects of the differentiation of the gastric glands]. / Aspetti istochimici del differenziamento delle ghiandole gastriche

The Authors have studied some aspects of the differentiation of gastric mucosa, during the prenatal and postnatal development in man and mouse. They have demonstrated that in both species the first elements of glandular rudiments can be already recognised, owing to the richness of their mitochondrial store, as parietal cells, where oxireductase activities are already present. The functional differentiation in the membrane of such elements takes place later on: from the point of view of the function the parietal cell can then be considered as completely differentiated. Chief cells, on the contrary, define their morphological and functional characters starting from the fifth month of foetal life. At any rate, at least for the studied characters, the gland store of human gastric mucosa, at birth and in the adult, is exactly alike.

Isolation and characterization of Leu 7+ germinal-center cells with the T helper-cell phenotype and granular lymphocyte morphology.

Leu 7+ cells in germinal centers of lymphoid tissues largely (greater than 90%) coexpress the T helper-cell marker, Leu 3. In this study we have isolated Leu 7+ (Leu 3+) cells from pharyngeal and palatine tonsils and we have analyzed their surface phenotype, morphologic and cytochemical characteristics, and functional properties. All of these features have been compared with those of T helper-cell populations with natural killer (NK)-like characteristics that we have previously described in peripheral blood. Leu 7+ (Leu 3+) cells from tonsil germinal centers display morphological and cytochemical features of granular lymphocytes and express the T3 marker in the absence of Leu 15. Following stimulation with phytohemagglutinin (PHA) or anti-T3, Leu 7+ (Leu 3+) cells express interleukin-2 (IL-2) receptors and proliferate to some extent in response to IL-2. The localization of Leu 7+ (Leu 3+) cells in B-dependent areas of lymphoid tissues suggests that they may play a regulatory role in B-cell proliferation and/or differentiation. Here we show that Leu 7+ (Leu 3+) cells do not produce B-cell growth factor (BCGF) and do not help pokeweed mitogen (PWM)-driven B-cell differentiation. Therefore, Leu 7+ (Leu 3+) germinal-center cells are distinct from "classic" T-helper cells of blood and lymphoid tissues.

[Preliminary observations on the distribution of serotoninergic and cerebellar-projecting neurons of the raphe nuclei of the brain stem]. / Osservazioni preliminari sulla distribuzione dei neuroni cerebello-proiettanti e serotoninergici dei nuclei rafeali del tronco encefalico.

Cerebellar projection from raphe nuclei were investigated in rabbit by using retrograde transport of HRP and serotonergic mapping by direct fluorescence. A close topographical correlation between the HRP labeled cells and the serotonergic neurons has been observed. The current study has demonstrated the presence of paramedian and lateral cells whose cytoarchitecture is identical with midline cells of many raphe nuclei. All of the raphe nuclei except the linear nuclei, contained serotonergic perikarya. The midline and paramedian portions of the nuclei raphe obscurus, pallidus, magnus, and nucleus raphe dorsalis contained principally serotonergic neurons; the lateral portions of the medullary raphe nuclei and the nuclei raphe pontis and centralis superior contained a significant number of non-fluorescent cells. In these regions, fluorescent sections often revealed the size, shape, and orientation of the perikarya and dendrites; further verification of cytoarchitectural characteristics of these neurons depended heavily upon these clues.

DNase I mediates internucleosomal DNA degradation in human cells undergoing drug-induced apoptosis.

Internucleosomal DNA fragmentation following the activation of endonucleases is the common end point of apoptosis. DNase I, a Ca(2+) / Mg(2+)-dependent endonuclease ubiquitously expressed in mammalian tissues, is believed to play a role in this process. To analyze the in vivo function of this enzyme in human cells, we have generated a cell line with targeted disruption of the DNase I gene, as well as several stable cell lines which overexpress the DNase I gene. Inactivation of the human DNase I gene was obtained in the Jurkat T cell clone JA3, characterized by high susceptibility to apoptotic cell death induced by pharmacological stimuli. JA3 cells, after disruption of the DNase I gene, became resistant to apoptotic stimuli. DNase I was overexpressed in the human cell lines JA3, K562 (erythroleukemia), M 14 (melanoma) and CEM (T cell lymphoma). Remarkably, stable overexpression of DNase I gene resulted in accelerated apoptosis in JA3 cells and induced apoptosis in K562, CEM and M14 cell lines, which are otherwise resistant to internucleosomal DNA degradation following pharmacological stimuli. Our study provides the first in vivo evidence that DNase I mediates internucleosomal DNA degradation in human cells undergoing drug-induced apoptosis.

Function and specificity of human natural killer cell receptors.

In humans, natural killer lymphocytes express HLA class I-specific inhibitory receptors belonging to at least two different molecular families. The first is represented by members of the Ig superfamily that are involved in the recognition of different groups of HLA class I alleles, and the second is represented by a molecular complex formed by CD94 and NKG2A that displays a broad specificity for various class I molecules including the 'non-classical' HLA-G molecules. In addition to the inhibitory receptors, a series of activating receptors has been identified. Some display the same specificities as the corresponding inhibiting receptors and can be viewed as HLA class I-specific activating receptors. Another group of activating receptors appear to be involved in the cytolytic activity against HLA-'negative' target cells. These receptors are clearly non-MHC specific and, under physiological conditions, their function is suppressed by the HLA class I-specific inhibitory receptors.