The use of monoclonal anti-T cell antibodies to study T cell imbalances in human diseases

Monoclonal antibodies are now available to evaluate human T cell subsets by direct counting using indirect immunofluorescence analysis. The critical use of these antibodies has already permitted the delineation of the T cell imbalances present in a number of immunologically mediated diseases such as autoimmune haemolytic anaemia, chronic active hepatitis, myasthenia gravis, glomerulonephritides, multiple sclerosis, leprosy, or immunodeficiency syndromes. The potential diagnostic and therapeutic application of this new methodology are emphasized.     

Fatal avian influenza A (H5N1) in a child presenting with diarrhea followed by coma

In southern Vietnam, a four-year-old boy presented with severe diarrhea, followed by seizures, coma, and death. The cerebrospinal fluid contained 1 white cell per cubic millimeter, normal glucose levels, and increased levels of protein (0.81 g per liter). The diagnosis of avian influenza A (H5N1) was established by isolation of the virus from cerebrospinal fluid, fecal, throat, and serum specimens. The patient's nine-year-old sister had died from a similar syndrome two weeks earlier. In both siblings, the clinical diagnosis was acute encephalitis. Neither patient had respiratory symptoms at presentation. These cases suggest that the spectrum of influenza H5N1 is wider than previously thought.     

High-performance liquid chromatographic analysis of the D4 receptor antagonist SCH 66712 in rat plasma

SCH 66712 is a potent and selective dopamine D4 receptor antagonist. An HPLC method was developed for the analysis of SCH 66712 in the plasma of rats, a species used for safety evaluation of this compound. The method involved solid-phase extraction on an ethyl cartridge and HPLC separation on a reversed-phase C8 column with quantitation using a fluorescence detector. The calibration curve was linear over a concentration range of 5-100 ng/ml. The limit of quantitation was 5 ng/ml, where the coefficient of variation (C.V.) was 2.9% and the bias was 6%. The precision of the method was satisfactory as indicated by an intra-day C.V. of < or = 4% and an inter-day C.V. of < or = 6%. The accuracy was also satisfactory as shown by an intra-day bias of < or = 8% and an inter-day bias of < or = 9%. The assay was shown to be sensitive, specific, accurate, precise, and reliable for use in pharmacokinetic or toxicokinetic studies.     

Development of a larval bioassay for susceptibility of cat fleas (Siphonaptera: Pulicidae) to imidacloprid

Strategies for controlling cat fleas, Ctenocephalidesfelisfelis (Bouché), have undergone dramatic changes in the past 5 yr. With the advent of on-animal treatments with residual activity the potential for the development of insecticide resistance increases. A larval bioassay was developed to determine the baseline susceptibility of field-collected strains of cat fleas to imidacloprid. All four laboratory strains tested showed a similar level of susceptibility to imidacloprid. Advantages of this bioassay are that smaller numbers of fleas are required because flea eggs are collected for the test. Insect growth regulators and other novel insecticides can also be evaluated. Using a discriminating dose, the detection of reduced susceptibility in field strains can be determined with as few as 40 eggs.     

Interferon: a cytotoxic T lymphocyte differentiation signal

Human T cell clones which were able to proliferate in response to specific stimuli but could not kill even in the presence of lectins were found to acquire the specific lytic function when interferon alpha or gamma was added on day 1 of the 7-day restimulation culture. These results demonstrate that interferon may act as a cytotoxic T lymphocyte differentiation signal. This signal can be blocked by the monoclonal antibody LeoA1 which recognizes a 70-kDa cell surface structure, involved in cytotoxic T lymphocyte differentiation.     

Distribution of HLA class II alleles and haplotypes in insulin-dependent moroccan diabetics

HLA class II polymorphism in Moroccan IDDM patients has not been investigated so far. In this study, HLA-DRB1, -DQA1, and -DQB1 allele and haplotype frequencies were analyzed in 125 unrelated Moroccan IDDM patients and 93 unrelated healthy controls, all originating from the Souss region and mostly of Berber origin. Some common features with other Caucasian groups were observed, in particular, a predisposing effect of the DRB1^*03-DQA1^*0501-DQB1^*0201 and DRB1^*04-DQA1^*0301-DQB1^*0302 alleles or allelic combinations. The Moroccan IDDM group also presented with more specific characteristics. Among DRB1^*04 subtypes, DRB1^*0405 was associated with susceptibility to and DRB1^*0406 with protection from the disease. The haplotype and the relative predispositional effect (RPE) analyses indicated that the DRB1^*08-DQA1^*0401DQB1 ^*0402 haplotype was also associated with susceptibility to IDDM. Interestingly, the DRB1^*09DQA1 ^*0301-DQB1^*0201 haplotype, completely absent from the control group and very rare in North African populations, was observed in 7.2% of the Moroccan diabetics. Conversely, the DRB1^*07-DQA1^*0201DQB1 ^*0201 and DRB1^*15-DQA1^*0102-DQB1^*0602 haplotypes were associated with protection from IDDM. Finally, we observed an age-dependent genetic heterogeneity of IDDM, the frequencies of predisposing alleles being higher and those of protective alleles lower in childhood- than in adult-onset diabetics. Our data on Moroccan diabetics, together with data on European and Northern Mediterranean patients, suggest a gradient of various HLA class II predisposing and protective markers that link these populations     

Wilms tumor in patients with osteopathia striata with cranial sclerosis

Germline pathogenic variants in AMER1 cause osteopathia striata with cranial sclerosis (OSCS: OMIM 300373), an X-linked sclerosing bone disorder. Female heterozygotes exhibit metaphyseal striations in long bones, macrocephaly, cleft palate, and, occasionally, learning disability. Male hemizygotes typically manifest the condition as fetal or neonatal death. Somatically acquired variants in AMER1 are found in neoplastic tissue in 15–30% of patients with Wilms tumor; however, to date, only one individual with OSCS has been reported with a Wilms tumor. Here we present four cases of Wilms tumor in unrelated individuals with OSCS, including the single previously published case. We also report the first case of bilateral Wilms tumor in a patient with OSCS. Tumor tissue analysis showed no clear pattern of histological subtypes. In Beckwith–Wiedemann syndrome, which has a known predisposition to Wilms tumor development, clinical protocols have been developed for tumor surveillance. In the absence of further evidence, we propose a similar protocol for patients with OSCS to be instituted as an initial precautionary approach to tumor surveillance. Further evidence is needed to refine this protocol and to evaluate the possibility of development of other neoplasms later in life, in patients with OSCS.Subject terms: Genetics, Clinical genetics, Disease genetics     

Comparative actions of biologic and synthetic leukotrienes on isolated human bronchus and rat mast cells

The effects of biologically prepared leukotriene C4 (LTCb) and leukotriene D4 (LTDb), obtained from rat monocytes stimulated with the calcium ionophore A23187, were compared with those of chemically synthetized leukotrienes (LTCs and LTDs) using two in vitro systems. All four leukotriene preparations (10(-10) to 6 X 10(-6) M) showed equal activity upon human bronchi, inducing slow, sustained contractions. LTCb alone (10(-7) to 6.9 X 10(-7) M) elicited histamine release and enhanced compound 48/80-induced release in a dose-dependent manner from rat mast cells. In contrast, LTDb alone was without effect but inhibited release caused by 48/80. FPL 55712 failed to block the LTCb and LTDb effects on the release process. The synthetic leukotrienes neither caused histamine release nor modulated 48/80-induced release from rat mast cells. We conclude that biologic and synthetic leukotrienes exhibit comparable contractile activity on isolated human bronchi but only biologic preparations modulate histamine release by previously unappreciated substances that isolate with the biologic leukotrienes.     

Cell-mediated immunity to pancreatic islet cells in the non-obese diabetic (NOD) mouse: in vitro characterization and time course study

The non-obese diabetic (NOD) mouse is an animal model of insulin-dependent diabetes mellitus (IDDM), in which 80% of the females become diabetic after the age of 12 weeks. Using an in vitro assay we investigated the capacity of spleen lymphocytes from NOD mice to inhibit the insulin secretion of normal islet cells after stimulation by theophylline plus arginine. Spleen cells from diabetic NOD mice inhibited the insulin release of DBA/2 islet cells. Depletion experiments using monoclonal antibodies demonstrated that inhibitory cells belonged to the Lyt2 positive T lymphocyte subset. The phenomenon was not restricted by the MHC class I K region, shared by NOD and DBA/2 mice, since lymphocytes from diabetic NOD mice also inhibited the insulin secretion of normal Wistar rat islet cells. Inhibitory T cells were detected in overtly diabetic mice but also in non-diabetic females aged 5-11 weeks indicating that they are not secondary to metabolic disturbances and might contribute to their onset. Conversely they were not found in male NOD mice although some of these mice show insulitis. The presence of these inhibitory T cells might thus represent an early and sensitive marker of anti-islet cell-mediated autoimmunity.