Changes in fetal rhesus monkey plasma dehydroepiandrosterone sulfate: relationship to gestational age, adrenal weight and preterm delivery

These studies were performed to assess the concentrations of dehydroepiandrosterone sulfate (DHAS) in the rhesus monkey fetal circulation from midgestation through the neonatal period, to determine the relation between changes in fetal adrenal size and DHAS levels both during gestation and after surgical stress, and to explore possible relations between changes in the concentration of DHAS in the fetal circulation and the initiation of labor. When plasma DHAS was quantified in cord blood and in serial samples from chronically catheterized rhesus monkey fetuses, a significant increase in plasma DHAS concentration occurred after 150 days gestational age (404 +/- 37 vs. 1093 +/- 159 ng/ml), and an additional increase was found after 159 days (2246 +/- 712 ng/ml). A diurnal change in fetal plasma DHAS occurred in chronically catheterized fetuses, with evening samples having higher values than morning samples. Further, there was an increase in plasma DHAS concentrations in the 4-5 days after fetal surgery. A significant increase in fetal plasma DHAS concentration occurred in the newborn rhesus monkey. Although plasma DHAS concentrations remained significantly higher than in the late gestation fetus, they decreased by approximately half within the first 2 weeks of life. A close correlation existed between fetal plasma DHAS and fetal adrenal weight in control fetuses delivered by hysterotomy and fetuses that were delivered 5 days after fetal surgery. Adrenal weights in the latter were significantly higher than those in comparably aged fetuses delivered by hysterotomy that had not undergone the stress of fetal surgery. The possible relationship between the increase in plasma DHAS and the initiation of labor was studied by monitoring the changes in daily morning DHAS concentrations in long term catheterized fetuses and comparing these values to the mean cross-sectional DHAS values corresponding to that gestational age. In all but one case, the values of DHAS, although they increased preceding delivery, were still within the range found in fetuses of the same gestational age that were not in labor. These data indicate that increases in DHAS are intimately related to parallel increases in fetal adrenal weight, that there are striking increases in DHAS levels near the end of gestation, that an increase in DHAS is a component of the fetal response to surgical stress, and that there is no immediately apparent, direct relationship between fetal DHAS and preterm delivery.     

Concordance of creatine kinase-MB activity and mass

The recent availability of monoclonal antibodies that are highly specific for creatine kinase (CK; EC 2.7.3.2) MB isoenzyme should allow for the development of rapid, sensitive, and specific assays of CK-MB mass and activity. However, the relationship between the mass concentration of CK-MB and its activity in plasma has previously been thought by some to be variable. To determine the extent to which discrepancies of potential clinical significance might arise between measurements of activity and mass in plasma, we compared CK-MB activity and concentration in 1298 samples obtained from 226 patients admitted to the cardiac-care unit. CK-MB activity concentration was determined with an immunoadsorption assay, and mass concentration was measured by an automated "sandwich" assay (Magic Lite; Ciba Corning Diagnostics). Both of these assays are based on specific monoclonal antibodies for CK-MB. Values obtained with these assays correlated well (r = 0.94). Normal and abnormal values with the two assays were concordant in 96% of the samples. In all but three instances, differences occurred late after myocardial infarction and were characterized by minimal increases as determined by one method vs values at the upper limit of normal as determined with the other. Thus, measurements of CK-MB mass and activity concentrations in plasma with assays based on these specific monoclonal antibodies are comparable for the detection or exclusion of acute myocardial infarction.     

Chediak-Higashi gene in humans. I. Impairment of natural - killer function

Natural-killer (NK)-cell function was profoundly depressed in donors homozygous for the Chediak-Steinbrinck-Higashi syndrome (C-HS) gene when compared with age- and sex-matched normals. This apparent defect was not simply a result of a delayed response because little cytolysis was evident in kinetics experiments even after 24 h of incubation. NK cells from C-HS donors failed to lyse adherent (MDA, CEM, and Alab) or nonadherent (K562 and Molt-4) tumor cell lines or nontransformed human fetal fibroblasts. Therefore, the apparent C-HS defect was not a result of a shift in target selectivities. In addition, the depressed reactivity did not appear to be a result of suppressor cells or factors because: (a) enriched NK populations (nonadherent lymphocytes bearing receptors for the Fc portion of IgG) from C-HS donors were low in NK-cell function, (b) C-HS mononuclear cells did not inhibit the cytotoxicity of normal cells in coculture experiments, and (c) cells from the C-HS donors remained poorly reactive even after culture for up to 7 d. The nature of the defective NK activity in C-HS patients is not clear but may lie within the lytic mechanism rather than at the level of the recognition structure or population size because the frequency of target-binding cells was normal. In vitro NK activity could be partially restored by interferon treatment. Combined with the results presented in the following paper (4), these observations suggest that the C-HS gene causes a selective immunodeficiency disorder, mainly involving NK cells. This finding, in conjunction with the high incidence of spontaneous possibly malignant, lymphoproliferative disorders in these patients, may have important implications regarding the theory of immune surveillance mediated by NK cells.     

Characteristics of human large granular lymphocytes and relationship to natural killer and K cells

Recent evidence, has demonstrated an association between a subpopulation of peripheral blood mononuclear cells, morphologically identified as large granular lymphocytes (LGL), and natural killer (NK) activity. We have now evaluated more directly the role of LGL in both NK activity and antibody- dependent cellular cytotoxicity (ADCC), by using highly enriched populations of LGL, obtained by centrifugation of peripheral blood mononuclear cells on Percoll discontinuous density gradients. Both spontaneous and interferon- augmented NK and ADCC activities were exclusively associated with the LGL- enriched, low density fractions. The majority of LGL formed conjugates with NK-susceptible and antibody-coated target cells. Approximately 20 percent of small conventional lymphocytes also formed conjugates with the target cells for NK, but this was not associated with cytotoxic activity. Virtually all LGL were found to have receptors for the Fc portion of IgG (FcγR). The frequency of LGL among blood leukocytes was 2-6 percent. LGL could be enriched to an average purity of 95 percent by combining discontinuous density gradient centrifugation with subsequent adsorptions of the low density fractions on monolayers of immobilized immune complexes. About 50 percent of LGL were found to be FcγR-bearing T cells (T(G)), forming low affinity rosettes with sheep erythrocytes at 4 degrees C. Only 10-20 percent of LGL formed high affinity rosettes with sheep erythrocytes at 29 degrees C. LGL could be enriched to a purity of more than 90 percent by depleting high affinity rosette-forming cells from low density Percoll fractions. LGL were only a subpopulation of T(G) cells, because some lymphocytes with conventional morphology also adhered to the immobilized immune complex monolayers and formed high affinity rosettes with sheep erythrocytes. Separation of these cells from LGL by discontinuous density gradient centrifugation indicated that they are not cytotoxic, suggesting a morphological and functional subdivision of T(G) cells. The verification in this study that virtually all human NK and K cells have a characteristic morphology adds a useful parameter to the monitoring of human lymphocytes, and the ability to purify these cells by simple physical procedures should be invaluable in their further characterization.     

The pathology of NK-cell lymphomas and leukemias

Natural killer (NK) cell lymphomas and leukemias are a rare but clinically important group of neoplasms. Most of these tumors are aggressive, with a high rate of mortality. They include extranodal NK/T-cell lymphomas of nasal type and aggressive NK-cell leukemias. Both are Epstein-Barr virus (EBV) associated and show similar epidemiologic features. A closely related entity seen mainly in children is hydroa vacciniforme-like lymphoma, which also is EBV positive. EBV influences the pathophysiology of these tumors, through the induction of cytokines and chemokines. The differential diagnosis of NK-cell malignancies includes fulminant EBV-associated T-cell lymphoproliferative disorder, a condition referred to in the past as fatal infectious mononucleosis. Benign proliferations of NK cells can be seen in association with viral infection. The disease formerly referred to as blastic NK-cell lymphoma is now considered to be a malignancy derived from a dendritic cell precursor.     

Frequent occurrence of deletions in primary mediastinal B-cell lymphoma

Primary mediastinal B-cell lymphoma (PMBCL) is a distinct subtype of diffuse large B-cell lymphoma. PMBCL has been previously studied with a variety of genomic techniques resulting in frequent detection of chromosomal gains; however, chromosomal losses have been rarely reported. This finding contrasts many other types of lymphoma, in which deletions are common. We hypothesize that segmental losses do exist but may have escaped detection by methods used in the previous studies. Using array comparative genomic hybridization to a tiling-resolution microarray encompassing the entire human genome, PMBCL samples were analyzed for genomic copy number alterations. An almost equal number of gains and losses of chromosomal material were detected throughout the genome (216 vs. 193, respectively). A selection of these DNA copy number alterations were confirmed by quantitative real-time PCR. Recurrent gains were detected at all previously reported regions of gain, including 9p seen in approximately 70% of cases. Recurrent chromosomal losses were observed at 1p, 3p, 4q, 6q, 7p, and 17p, with a novel event at 1p13.1-p13.2 representing the most frequent at 42% of cases analyzed. We conclude that consistent losses are present in the PMBCL genome. Given the similar frequency of losses to that of segmental gains of DNA, they are likely to play an important role in the pathogenesis of PMBCL.     

Depolymerisation and rearrangement of actin filaments during exocytosis in rat peritoneal mast cells: involvement of ryanodine-sensitive calcium stores

Cytoskeletal F-actin associated with synaptic vesicles and granules plays an important role during Ca²⁺-mediated exocytosis. In the present work, we have used amperometry and confocal fluorescence to study the role of internal Ca²⁺ in the rearrangement of F-actin (visualised with phalloidin-Alexa 546) during exocytosis in rat mast cells. The F-actin-depolymerising drug, latrunculin A, and the ryanodine receptor agonists ryanodine and caffeine that, per se did not induce exocytosis, enhanced the exocytotic responses elicited by compound 48/80 (C48/80). They also induced cortical actin depolymerisation in the presence or absence of external Ca²⁺. Degranulation induced by C48/80 was accompanied by the formation of a cytoplasmic F-actin network. Depletion of internal Ca²⁺ with cyclopiazonic acid inhibited latrunculin potentiation of C48/80-stimulated exocytosis and completely blocked the formation of the cytoplasmic F-actin network. This indicates that the mobilisation of Ca²⁺ from ryanodine-sensitive intracellular stores plays an important role in the depolymerisation of the cortical F-actin barrier and possibly in the formation of the internal F-actin network during exocytotic activation of peritoneal mast cells.     

MIP-1alpha expression in tissues from patients with hemophagocytic syndrome

Hemophagocytic syndrome (HPS) is a clinicopathologic syndrome that can be precipitated by a variety of causes and is characterized by a systemic activation of macrophages, which are induced to undergo phagocytosis. Chemokines play an important role in the inflammatory cell recruitment into tissues. We examined the expression of chemokines and cytokines in tissues exhibiting histologic evidence of HPS in a variety of settings: peripheral T-cell lymphoma, three patients; nasal T/NK cell lymphoma, one patient; subcutaneous panniculitis-like T-cell lymphoma, one patient; and chronic EBV infection, one patient. Compared with control tissues, we found elevated macrophage inflammatory protein-1alpha (MIP-1alpha) and interferon-gamma (IFN-gamma) expression, but not macrophage-derived chemotactic factor (MDC) or TNF-alpha, in tissues of patients with HPS irrespective of the cause or setting. MIP-1alpha can promote macrophage chemotaxis and IFN-gamma promotes macrophage activation. Elevated expression of IP-10 and monokine induced by IFN-gamma (Mig) was also detected in tissues exhibiting features of HPS, providing an explanation for the occurrence of chemoattraction of T-cells and NK cells. Immunohistochemical analysis of tissues with evidence of phagocytic activity in that site showed MIP-1alpha characteristically localized to endothelial cells of blood vessels and splenic sinuses, lymphocytes, and macrophages. These results provide evidence for MIP-1alpha chemokine expression in tissues from patients with HPS and suggest that MIP-1alpha may play an important role in the pathogenesis of the hemophagocytic syndrome.