Immunostaining for α1-antichymotrypsin and α1-antitrypsin in gliomas

Antisera to α₁-antichymotrypsin, α₁-antitrypsin and lysozyme were reacted with 20 cases of glioblastoma multiforme, seven anaplastic astrocytomas, eight astrocytomas, six oligodendrogliomas, four ependymomas and the cerebral cortex from six normal autopsy brains. In addition, two pleomorphic xantho-astrocytomas and two heavily lipidized malignant gliomas were similarly examined. All astrocytic lesions were confirmed with anti-GFAP antisera. Thirty astrocytic tumours (77%), four oligodendrogliomas (67%) and three ependymomas (75%) reacted positively with anti-α₁-antichymotrypsin; 25 astrocytic tumours (64%), three oligodendrogliomas (50%) and three ependymomas (75%) showed positive staining for α₁-antitrypsin. The pattern of staining with either of these two markers did not correlate with tumour grading. None of the gliomas examined stained positively with anti-lysozyme. Non-neoplastic glial elements did not react with any of the three antisera. The results of this study suggest that staining for α₁-antichymotrypsin and α₁-antitrypsin is of little value in the differential diagnosis of neuroepithelial or mesenchymal lesions in the brain.     

Increased expression of collagen receptors: α1β1 and α2β1 integrins on blood eosinophils in bronchial asthma

BACKGROUND: Eosinophils are one of the major effector cells in bronchial asthma. Their infiltration of airways correlates with the asthma severity. Recruitment and activation of eosinophils are partially mediated by integrins alpha4beta1 and alpha4beta7. Collagens type I and IV constitute important components of extracellular matrix and vascular basement membrane, respectively. Therefore, collagen-binding integrins (alpha1beta1 and alpha2beta1) may also play a role in eosinophil lung infiltration. OBJECTIVE: To evaluate the possible presence of alpha1beta1 and alpha2beta1 integrins on peripheral blood eosinophils from asthmatic subjects. METHODS: Collagen receptors were studied on eosinophils separated by immunomagnetic CD16-negative method from healthy donors (n=13) and patients with moderate persistent atopic bronchial asthma (n=15). Surface receptor identification was performed by flow cytometry and cell adhesion assay. RESULTS: Eosinophils isolated from the patients showed increased expression of both alpha1beta1 and alpha2beta1 integrins as compared with healthy controls. Moreover, adhesive function of eosinophils to collagen type IV was inhibited by snake venom disintegrins: viperistatin and obtustatin. These disintegrins contain KTS active motif and are specific inhibitors of alpha1beta1 integrin. CONCLUSION: We demonstrated for the first time that collagen receptors: alpha1beta1 and alpha2beta1 integrins are overexpressed on the surface of peripheral blood eosinophils of asthmatic subjects. Further studies may reveal potential application of KTS-disintegrins or their structural analogs for therapy of bronchial asthma.     

Complexes in Human Plasma between α1-Antitrypsin and IgA, and α1-Antitrypsin and Fibrinogen

Crossed immunoelectrophoretic analyses revealed that plasma contains a complex between α₁-antitrypsin¹ and IgA. Normally the complex constitutes 1–2% of these proteins. The amount varies mainly with the IgA and to some extent with the α₁-at content of the plasma. The complex is sensitive to thiol reagents and is reduced in vivo by penicillamine. The size of the complex and the amount of reduction products are compatible with the assumption of 1 IgA monomer or dimer per α₁-at molecule. An α₁-at complex with fibrinogen is also a regular plasma constituent. This complex is not susceptible to thiol reagents.     

Heterozygous α-antichymotrypsin and PiZ (α1-antitrypsin deficiency

In a case-control study we compared the prevalence of heterozygous deficiency of two closely related anti-neutrophil protease inhibitors, alpha 1-antitrypsin and alpha 1-antichymotrypsin, in 172 consecutive children with asthma. In a cohort study the clinical spectrum and severity were compared. On the basis of family studies 5/172 (2.9%) were classified as heterozygotes for alpha 1-antichymotrypsin deficiency, a high prevalence compared with that of an unselected adult population (prevalence ratio 4.5 (1.7-11.9), P less than 0.005). This finding suggests that the carrier state of this rare allele (prevalence 0.64%) may predispose to asthma in children. Among these heterozygous patients the prevalence of positive RAST tests for foodstuffs was significantly increased (prevalence ratio 4.8 (1.7-13.2), P less than 0.005) and 2/5 manifested food allergy with Quincke oedema. Either the PiMZ or SZ phenotype of alpha 1-antitrypsin deficiency was found in 12 (7.0%) of the 172 patients, a prevalence similar to that of a normal population (prevalence ratio 1.3 (0.67-2.6), P = 0.44). However, the asthma was more severe among the Z allele carriers, judged by the number of hospital admissions, compared with the non-Z asthmatic children (mean 2.92 vs. 1.72, P less than 0.05). The results indicate that heterozygous deficiency of protease inhibitors directed against neutrophil proteases may affect the severity and clinical spectrum of childhood asthma, and to some degree be predisposing.     

Predominant α2/β2/γ3 AMPK activation during exercise in human skeletal muscle

5'AMP-activated protein kinase (AMPK) is a key regulator of cellular metabolism and is regulated in muscle during exercise. We have previously established that only three of 12 possible AMPK α/β/γ-heterotrimers are present in human skeletal muscle. Previous studies describe discrepancies between total AMPK activity and regulation of its target acetyl-CoA-carboxylase (ACC)β. Also, exercise training decreases expression of the regulatory γ3 AMPK subunit and attenuates α2 AMPK activity during exercise. We hypothesize that these observations reflect a differential regulation of the AMPK heterotrimers. We provide evidence here that only the α2/β2/γ3 subunit is phosphorylated and activated during high-intensity exercise in vivo . The activity associated with the remaining two AMPK heterotrimers, α1/β2/γ1 and α2/β2/γ1, is either unchanged (20 min, 80% maximal oxygen uptake     ) or decreased (30 or 120 s sprint-exercise). The differential activity of the heterotrimers leads to a total α-AMPK activity, that is decreased (30 s trial), unchanged (120 s trial) and increased (20 min trial). AMPK activity associated with the α2/β2/γ3 heterotrimer was strongly correlated to γ3-associated α-Thr-172 AMPK phosphorylation ( r ²= 0.84, P < 0.001) and to ACCβ Ser-221 phosphorylation ( r ²= 0.65, P < 0.001). These data single out the α2/β2/γ3 heterotrimer as an important actor in exercise-regulated AMPK signalling in human skeletal muscle, probably mediating phosphorylation of ACCβ.     

Immunosuppressive Properties of α1-Microglobulin

α₁-Microglobulin (α₁m), a serum glycoprotein (26,000 d). was found to impede the proliferative response of human lymphocytes to purified protein derivative (PPD) and tetanus toxoid. The data suggest that, α₁m operates through an unstable suppressor mechanism, which no longer can function after 24 h of preculturing. This effect of α₁m on antigen stimulation did not seem to be due to binding of α₁m to PPD or cells, to altered kinetics of the PPD response, or to non-specific cytotoxicity. In contrast, PPD-induced leucocyte migration inhibition was not reversed by α₁m. α₁m did not cause significant inhibition in experiments in which lymphocytes were stimulated by the mitogens phytohaemagglutinin or concanavalin A. Finally, α₁m had its own leucocyte migration inhibitory effect.     

α1-Antitrypsin deficiency in twins and parents-of-twins

Serum-trypsin-inhibitory-capacity (STIC) and alpha1-antitrypsin (AAT) genotypes were evaluated in 83 twins and 112 paired parents-of-twins. An increased prevalence (17.0--21.9%) of intermediate AAT deficiency (STIC less than 0.95 units/ml) was detected in both of these groups as compared to a prevalence of 4.1% in 1,841 healthy controls. PiS and PiZ molecular variants of AAT were also found more frequently in the twin and parent groups, but this was not statistically significant. Low levels of protease inhibition may enhance fertility and a tendency towards twinning, since proteolytic enzymes are involved in fertilization of ova by sperm and in gametogenesis. Increased fertility and twinning may be heterozygous advantages for AAT deficiency.     

Immunological parameters and α1-antitrypsinin chronic urticaria

Serum immunoglobulins, complement and α₁-antitrypsin were assayed in forty-eight patients with chronic urticaria. Thirteen cases had chronic cold urticaria and thirty-two had chronic idiopathic urticaria. Elevated mean serum IgM was found in chronic cold urticaria. Seven patients had partial immunoglobulin deficiencies. IgE was elevated in sixteen cases of chronic idiopathic and in two with chronic cold urticaria. Eight patients had depressed serum total haemolytic complement activity. Low C3 and normal C4 serum protein concentrations in four cases suggested alternative complement pathway activation. Twenty of forty-six patients were atopic, although specific allergies responsible for the urticaria were not identified in any of them. α₁-antitrypsin levels were normal in all patients. The data suggest that the aetiology and pathogenesis of chronic urticarias in this study are heterogeneous. No evidence of abnormality of the protease inhibitor system in either chronic idiopathic or chronic cold urticaria was found.     

Intermediate α1-antitrypsin deficiency in atopic allergy

In a population of over 200 patients with atopic bronchial disease, significantly increased frequencies of the α₁-antitrypsin Pi-types of intermediate deficiency (Pi MZ and Pi MS) were found. As far as we are aware of, this report is the first in which strictly objective criteria for patient classification with respect to atopy have been used. A possible biochemical basis for the phenomenon is presented.     

α1-antitiypsin deficiency and the flaccid lung syndrome

A significantly higher number of PI ZZ and PI MZ individuals was found in a flaccid lung population as compared to internal and healthy controls. The relative risk for ZZ is 12.5 and for MZ 1.8. We conclude that if a PI MZ individual does develop lung disease, the excess risk due to the deficiency is negligible compared to MM individuals and is highly influenced or modified by other factors, possibly including both environmental and genetic.     

Specific contribution of human T-type calcium channel isotypes (α1G, α1H and α1I) to neuronal excitability

The glutamine transporter SN1 has recently been identified as one of the major glutamine transporters in hepatocytes and brain astrocytes. It appears to be the molecular correlate of system N amino acid transport. Two different transport mechanisms have been proposed for this transporter. These are an electroneutral mechanism, in which glutamine uptake is coupled to an exchange of 1Na⁺ and 1H⁺, or an electrogenic mechanism coupled to the exchange of 2Na⁺ against 1H⁺. This study was performed to solve these discrepancies and to investigate the reversibility of the transporter. When SN1 was expressed in Xenopus laevis oocytes, glutamine uptake was accompanied by a cotransport of 2–3 Na⁺ ions as determined by ²²Na⁺ fluxes. However, at the same time a rapid release of intracellular Na⁺ was observed indicating an active exchange of Na⁺ ions. The driving force of the proton electrochemical gradient was equivalent to that of the sodium electrochemical gradient. Acidification of the extracellular medium caused the transporter to run in reverse and to release glutamine. Determination of accumulation ratios at different driving forces were in agreement with an electroneutral 1Na⁺-glutamine cotransport-1H⁺ antiport. Inward currents that were observed during glutamine uptake were much smaller than expected for a stoichiometric cotransport of charges. A slippage mode in the transporter mechanism and pH-regulated endogenous oocyte cation channels are likely to contribute to the observed currents.     

Immunohistochemical Investigation of Vimentin, Neuron-specific Enolase, α1-antichymotrypsin and α1-antitrypsin in Adenoid Cystic Carcinoma of the Salivary Gland

Fifty-four adenoid cystic carcinomas (ACC) arising in major and minor salivary glands as well as in normal salivary glands were studied by immunohistochemistry for the presence of vimentin, neuron specific enolase (NSE), α₁-antichymotrypsin (α₁-ACT) and α₁-_- antitrypsin (α₁-_- AT). Five patterns of histological differentiation were found in ACC, and for the cellular components of each, it was possible to establish a special immunohistochemical profile. In ACC, vimentin-positive cells were observed in the outer tubular, cyst-lining and small angular cells. NSE was positive in the myoepithelial cells of normal salivary gland. Neoplastic cells of ACC showed NSE positivity mainly in the small angular cells and partly in the duct luminal cells. α₁-ACT was localized in the intercalated duct cells and serous acinar cells of normal salivary gland, and in the duct luminal cells of ACC. α₁-AT could not be detected in any of the epithelial cells of normal salivary gland. In ACC, eosinophilic hyaline material in the cribriform spaces was positive for α₁-AT, but no positivity was demonstrated in tumor cells. The present study showed that there are at least two populations of tumor cells in ACC: duct luminal cells that express α₁-ACT, thus indicating their ductal character, and small angular cells that express vimentin, characteristic of non-luminal cells. Moreover, our results indicate that α₁-AT is a useful marker of basement membrane-like material.     

Relationship of Pregnancy-Associated Alpha2-Glycoprotein (α2PAG) to Peripheral Blood Leucocytes

The high molecular weight plasma glycoprotein pregnancy-associated alpha2-glycoprotein (alpha2-PAG) can be demonstrated on the surface of blood leucocytes and is synthesized by oestrogen-stimulated cells in culture. By the use of an indirect immunofluorescence technique, pretreatment of leucocytes with anti-alpha2-PAG IgG revealed alpha2-PAG on C3 rosette-forming cells and monocytes but not on E rosettes. Lymphocytes treated with anti-alpha2-PAG showed markedly diminished ability to form Fc rosettes. A percentage ranging from 15% to 20% of leucocytes from normal adults of both sexes, pregnant and oestrogen-treated females were positive for alpha2-PAG but no obvious correlatin was observed between the incidence of alpha2-PAG bearing cells and plasma levels of the protein.