The cytotoxic HLA-DQ3 reactive human hybridoma antibody 4166 that May distinguish DQ7 + 8 from DQ9

The human cytotoxic hybridoma antibody 4166 (IgM_χ) was generated by fusing an in vitro EBV-transformed B-LCL from a multiparous woman with the mouse-human heteromyeloma fusion partner CB-F7. In microcytotoxicity and IIF tests with B-LCLs as target cells, the mAb 4166 was specific for DQ3 ( = DQ7 + 8 + 9). However, when used for DQ typing of class-II-positive PBMCs, 4166 could be rendered functionally specific for DQ7 + 8and did not react with DQ9⁺ PBMCs. Binding of mAb 4166 to DQ8-positive cells was efficiently blocked by several allotype-specific mAbs recognizing DQ8. Other HLA class-II-specific mAbs were unable to inhibit. With the use of mAb 4166, it is possible to discriminate DQ7 + 8 from DQ9 in serologic DQ typing.     

Muscle fibre type,efficiency, and mechanical optima affect freely chosen pedal rate during cycling

This study investigated the variation in freely chosen pedal rate between subjects and its possible dependence on percentage myosin heavy chain I (%MHC I) in m. vastus lateralis, maximum leg strength and power, as well as efficiency. Additionally, the hypothesis was tested that a positive correlation exists between percentage MHC I and efficiency at pre-set pedal rates but not at freely chosen pedal rate. Twenty males performed cycling at low and high submaximal power output ( approximately 40 and 70% of the power output at which maximum oxygen uptake (VO(2max)) was attained at 80 r.p.m.) with freely chosen and pre-set pedal rates (61, 88, and 115 r.p.m.). Percentage MHC I as well as leg strength and power were determined. Freely chosen pedal rate varied considerably between subjects: 56-88 r.p.m. at low and 61-102 r.p.m. at high submaximal power output. This variation was only partly explained by percentage MHC I (21-97%) as well as by leg strength and power. Interestingly, %MHC I correlated significantly with the pedal rate at which maximum peak crank power occurred (r = -0.81). As hypothesized, %MHC I and efficiency were unrelated at freely chosen pedal rate, which was in contrast to a significant correlation found at pre-set pedal rates (r = 0.61 and r = 0.57 at low and high power output, respectively). Conclusions: Subjects with high percentage MHC I chose high pedal rates close to the pedal rates at which maximum peak crank power occurred, while subjects with low percentage MHC I tended to choose lower pedal rates, favouring high efficiency. Nevertheless, the considerable variation in freely chosen pedal rate between subjects was neither fully accounted for by percentage MHC I nor by leg strength and power. Previously recognized relationships between percentage Type I ( approximately %MHC I) and efficiency as well as between pedal rate and efficiency were confirmed for pre-set pedal rates, but for freely chosen pedal rate, these variables were unrelated.     

Anti-diabetogenic effect of fusidic acid in diabetes prone BB rats.

Fusidic acid and its sodium salt (fusidin) are anti-staphylococcal drugs. In vitro studies have shown that they prevent the lymphocyte co-stimulatory activities of the cytokines IL-1 and IL-6 in a manner similar to that of cyclosporin A, and prevent the inhibitory effect of IL-1 on glucose-induced insulin production. As IL-1 and IL-6 are thought to play a role in the pathogenesis of Type 1 diabetes, the aim of this study was to investigate whether fusidin could influence the disease incidence of the spontaneously diabetic BB rat model. Accordingly, a group of 50 BB rats receiving fusidin dissolved in their drinking water were compared to a control group of 55 rats over a period of 200 days. The incidence of diabetes was found to be 52% in the experimental group and 71% in the control group (P < 0.05). The degree of insulitis and the number of islets at histological examination were similar among the non-diabetic animals whereas the diabetic fusidin-treated animals showed a higher degree of islet preservation than the diabetic control rats. The results are highly indicative of an anti-diabetogenic effect of fusidin.     

SV40 defectives selected during low multiplicity passage on A172 human glioblastoma cells

The gliobastoma line, A172, is unusual among human cell lines in being permissive for SV40 infection, and differs from many host cell types in allowing the accumulation of viral defectives on low multiplicity passage. We have characterized these A172-derived defectives and find that most are reiteration mutants, containing multiple copies of both the viral replication origin (including the BglI site at map position 0.659) and sequences from the opposite side of the standard genome (around the BamHI site at map position 0.143). This distinguishes them from defectives accumulated during high-multiplicity passage in monkey cells, which generally have only reiterated origins. When well characterized, monkey cell-derived defectives (ev-1101, d₅ a₃, a′₄) were passed in A172 cells, the characterized defectives were lost, and sometimes replaced by other defectives present in the same stock. Surprisingly, this was true even when the characterized defective carried sequences from the BamHI region of standard SV40. These findings are taken to support the notion that sequences in addition to the viral replication origin are positively selected during defective propagation, but that different requirements for such sequences are set by monkey cells and A172 cells.     

Lymphocyte Responses to an Aqueous Extract from Cow Hair and Dander

The proliferative responsiveness to cow dander antigens of lymphocytes from 23 asthmatic patients with allergy to cow hair and dander, from 10 patients with allergic asthma to other antigens and from 31 non-atopic subjects was investigated. Lymphocytes from patients with allergic asthma due to cow epithelium antigens showed a statistically significant decreased responsiveness to an extract from cow dander, compared to that seen with lymphocytes from newborn infants, lymphocytes from normal controls and from asthmatic patients without allergy to cow. The response to the cow dander extract seemed to be an accessory cell dependent T lymphocyte response.     

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.     

The evolution and breakdown of the immune system: implications for development of autoimmune diseases

At the most recent meeting of the Scandinavian Society for Immunology in Bergen, one of the major target phenomena was autoimmune diseases. The approach started from the evolutionary origins of immunity, went on to review some of the notable advances in molecular architecture of immune processes and finally focussed the findings on autoimmune disease.     

Outer membrane protein binding sites of complement component 3 during opsonization of Haemophilus influenzae.

Complement component 3 (C3) binding to Haemophilus influenzae type b (Hib) is an important step in host defense against invasive disease, but the details of this process remain poorly understood. We have shown that the P1 and P2 outer membrane proteins (OMPs) serve as binding sites for C3 on serum-opsonized Hib. Whole-cell lysates of opsonized Hib were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the resolved proteins were transferred to nitrocellulose. Immunoblot analysis with monoclonal antibodies (MAbs) to the 49-kDa P1 and 39-kDa P2 OMPs demonstrated high-molecular-weight bands that were not present when the bacteria were opsonized with heat-inactivated or methylamine-treated serum. Immunoblot analysis with MAbs to the 98- or 16-kDa (P6) OMPs did not reveal additional bands. An unencapsulated Hib mutant still lacked C3 bound to the 98-kDa or P6 OMP, indicating that the absence of C3 binding to these proteins was not the result of epitope masking by the capsule. Studies with MAbs to C3 fragments confirmed that the anti-P1- and anti-P2-reactive bands were C3 fragments bound to these OMPs. The molecular weights of proteins reactive to anti-OMP and anti-C3 antibodies indicated that multiple C3 fragments may be bound to P1 or that C3 may be bound to P2 multimers. Finally, the presence of other anti-C3-reactive proteins indicated that several other proteins serve as C3 targets during the opsonization of Hib.