Inhibitory effect of an antibody against alpha 1-acid glycoprotein (alpha 1-AGP) on autologous mixed lymphocyte reaction and anti-T3 T-lymphocyte activation

One step purification of alpha(1)-acid glycoprotein from human plasma. Fractionation of its polymorphic allele products

Alpha(1)-acid glycoprotein is a plasma protein that exhibits both microheterogeneity and polymorphism. Its purification from human plasma is usually performed using a sequence of different fractionation steps. Here we report a one-step isolation technique of this protein based upon pseudo-ligand affinity chromatography on immobilized Cibacron Blue F3GA at acidic pH. In addition, the use of two narrow pH elution buffers allows us to separate the two genetic products of this protein, which differ from each other by 21 amino acid substitutions. This technique will facilitate the study of the structural, biological and pharmacokinetic properties of each individual allele product.

Human alpha-1-glycoprotein and its interactions with drugs

For about half a century, the binding of drugs to plasma albumin, the "silent receptor," has been recognized as one of the major determinants of drug action, distribution, and disposition. In the last decade, the binding of drugs, especially but not exclusively basic entities, to another plasma protein, alpha 1-acid glycoprotein (AAG), has increasingly become important in this regard. The present review points out that hundreds of drugs with diverse structures bind to this glycoprotein. Although plasma concentration of AAG is much lower than that of albumin, AAG can become the major drug binding macromolecule in plasma with significant clinical implications. Also, briefly reviewed are the physiological, pathological, and genetic factors that influence binding, the role of AAG in drug-drug interactions, especially the displacement of drugs and endogenous substances from AAG binding sites, and pharmacokinetic and clinical consequences of such interactions. It can be predicted that in the future, rapid automatic methods to measure binding to albumin and/or AAG will routinely be used in drug development and in clinical practice to predict and/or guide therapy.

Defective calcium increase and inositol phosphate production in anti-CD3-stimulated lymphocytes of alcoholics without progressive liver disease

Intracellular free calcium concentration, phosphoinositide turnover, and inositol phosphate production were analyzed in peripheral blood lymphocytes from seven well-nourished alcoholic patients without severe acute or chronic liver disease, before and after stimulation with anti-CD3 antibody. Seven comparable nondrinkers were studied as controls. A lower increase in intracellular free calcium concentration was detected in alcoholics, after anti-CD3 stimulation of lymphocytes, than in control subjects. Lymphocyte activation generated inositol phosphates in both controls and alcoholics, but inositol phosphate production was significantly lower in alcoholics. The agreement between these findings indicates that the reduction in inositol phosphates is one of the most important events in the early phases of lymphocyte activation in alcoholics.

Alpha 1-acid glycoprotein (orosomucoid): pathophysiological changes in glycosylation in relation to its function

The aim of this review is to summarize the research efforts of the last two decades with respect to (i) the determination and characterization of the changes in glycosylation of AGP under various physiological and pathological states; and (ii) the effects of such changes on its possible anti-inflammatory functions. It will become clear that the heterogeneity observed in the glycosylation of AGP in serum, represents various so-called glycoforms of AGP, of which the relative amounts are strictly determined by the (patho) physiological conditions.

Modulation of alpha 1-acid glycoprotein (AGP) gene induction following honey bee venom administration to adjuvant arthritic (AA) rats; possible role of AGP on AA development

Honey bee venom (HBV) administration to adjuvant arthritic (AA) rats resulted in a significant suppression of arthritis and in suppression of the hepatic acute phase alpha 1-acid glycoprotein (AGP) gene induction at the early stages of disease development. AGP administration in AA rats resulted in acceleration of arthritis development and in increase of severity and duration of the disease. IL-1, IL-6, tumour necrosis factor (TNF) and glucocorticoids alone are not responsible for the HBV-mediated AGP gene down-regulation. These results indicate that AGP gene expression in AA and HBV-treated AA rats involves the interaction of several factors, and that AGP plays a role for AA development in rats.

In vivo effect of chronic ethanol consumption on the fatty acid composition of phosphatidylinositols in resting and anti-CD3-activated lymphocytes

Fatty acid composition of phosphatidylinositols was analyzed in peripheral blood lymphocytes from nine alcoholic patients who were well nourished and without severe acute and chronic liver disease, before and after stimulation with anti-CD3 antibody. Six comparable nondrinkers were studied as controls. A reduction in unsaturated fatty acid (mainly arachidonic) and an increase in palmitic and stearic acid molar content were observed in phosphatidylinositol (PI), phosphatidylinositol-4-phosphate (PIP), and phosphatidylinositol-4,5-bisphosphate (PIP2) in unstimulated samples from alcoholic patients in comparison with normal subjects, leading to a significant decrease in the saturated/unsaturated ratio. In controls, anti-CD3 stimulation caused a marked decrease in arachidonic acid relative molar content counterbalanced by an increase in other polyunsaturated fatty acid relative molar content in PI, PIP, and PIP2 fractions. Interestingly, after anti-CD3 stimulation, alcoholic patients show the same trend of modification in the fatty acid composition resulting in a sharp reduction of arachidonic acid relative molar content. These results support the hypothesis of an alteration in nutrients being responsible for immune derangement in alcoholics.

Alpha 1-acid glycoprotein expression in human leukocytes: possible correlation between alpha 1-acid glycoprotein and inflammatory cytokines in rheumatoid arthritis

alpha 1-Acid glycoprotein is an acute-phase reactant that becomes markedly elevated in serum during inflammation and has an immunosuppressive effect on lymphocyte functions. Patients with collagen diseases had significant increases of alpha 1-acid glycoprotein in their serum and on the surface of peripheral leukocytes compared with controls. The levels from patients with rheumatoid arthritis were higher than those from patients with systemic lupus erythematosus, mixed connective tissue disease, and Behçet's disease. In patients with rheumatoid arthritis, the value of serum alpha 1-acid glycoprotein correlated with disease activity. Among leukocyte subpopulations, monocytes showed more alpha 1-acid glycoprotein on their surface than polymorphonuclear leukocytes and lymphocytes. The cell surface expression of alpha 1-acid glycoprotein on cultured monocytes surface peaked after 48 h. Interleukin-1 beta and tumor necrosis factor-alpha stimulated the production of alpha 1-acid glycoprotein RNA message in peripheral blood mononuclear cells over 18-24 h during cell culture. The results show that serum alpha 1-acid glycoprotein reflects systemic disease activity in rheumatoid arthritis. Furthermore, monocytes may serve as a source of production of alpha 1-acid glycoprotein.

Functional involvement of the LFA-1/ICAM-1 adhesion system in the autologous mixed lymphocyte reaction

The integrin surface molecule termed lymphocyte functional antigen-1 (LFA-1), and its physiological ligand intercellular adhesion molecule-1 (ICAM-1), have been proven to play a relevant role in several immune reactions where cell-to-cell contact is required: these reactions include allogeneic mixed lymphocyte reaction (MLR) and direct cytotoxicity. In the present study, we show that monoclonal antibodies (mAbs) directed to LFA-1 as well as to ICAM-1 molecules are able to inhibit T cell proliferation in autologous MLR (AMLR). Such an in vitro reaction is generally considered a functional model of Ia-mediated immunocompetent cell cooperation, and is impaired in several pathological conditions. It is noteworthy that the LFA-1 molecule is largely represented on the T cell surface, whereas ICAM-1 is poorly expressed on resting T cells: autologous stimulation slightly increases ICAM-1 expression. Pretreatment studies indicate that the inhibitory effect of anti-ICAM-1 mAb on T cell proliferation in AMLR is exerted on responder T cells.

In vivo effect of chronic ethanol abuse on membrane alpha 1-glycoprotein of lymphocytes and immune response to various stimulating agents

Data on the immune status of chronic alcoholic patients are rather conflicting probably due to the interference of liver disease and/or malnutrition on immune function. In order to avoid this kind of interference, peripheral lymphocytes from 12 chronic alcoholic patients in good nutritional status and without heavy liver damage and 15 healthy controls were examined in this study. Lymphocyte functional activity was evaluated by means of response to phytohemagglutinin, calcium ionophore A 23187, and autologous non-T-cells [autologous mixed lymphocyte reaction (AMLR)]. Phenotypical analysis was carried out by the indirect immunofluorescence technique using monoclonal antibodies specific to CD5 (mature T-lymphocytes), CD4 (helper/inducer T-lymphocytes), CD8 (suppressor/cytotoxic T-lymphocytes), glycoproteins, and an immunoglobulin fraction from rabbit directed to membrane alpha 1 acid glycoprotein (AGP) that is involved in T-cell activation process. Our results show significant impairment in AMLR while response to phytohemagglutinin, heterologous non-T-cells and carcinoma ionophore did not differ from controls. No differences were present in circulating T-lymphocytes expressing CD5, CD4, and CD8 on their membrane, whereas AGP-bearing lymphocytes were significantly lower in chronic alcoholics (14.4 +/- 8.6) than in controls (31.9 +/- 8.1; p less than 0.001). These results support the hypothesis of a direct action of alcohol on one of the pathways of lymphocyte activation and the role of the lymphocyte membrane AGP on the AMLR.

Functional study of T lymphocyte responsiveness in patients with dementia of the Alzheimer type

The autologous mixed lymphocyte reaction (AMLR) was used to study T lymphocytes in a group of patients with dementia of the Alzheimer type (DAT) in order to confirm the observation that their T cell proliferation in AMLR was greater than in age-matched controls, and to investigate other pathways of T cell activation, searching for correlations between immunologic and clinical findings in DAT. The mean proliferative response in AMLR was increased in patients with DAT. No differences between patients and age-matched controls were detected when other pathways of T cell activation were investigated. The degree of response in the AMLR varied among patients with DAT. This fits with the suggestion that the disorder may be a heterogeneous syndrome.

T cell activation through different membrane structures (T3/Ti, T11, T44) and frequency analysis of proliferating and interleukin-2 producer T lymphocyte precursors in aged individuals

It is well known that the proliferative responsiveness of T cells of aged subjects is depressed in both autologous mixed lymphocyte reaction (AMLR) and in PHA-induced cultures. In the present study we analyzed T cell activation through different stimulatory pathways (such as T3/Ti antigen receptor, T11 complex and T44 molecule). Moreover, we studied Interleukin-2 (IL-2) release performing a limiting dilution analysis of the proliferative capability of peripheral blood T cells, employing a high efficiency cloning technique. Our results demonstrate normal proliferation of T3-induced T cells in aged subjects, whereas T11- and T44-induced T cell proliferations are depressed in aged subjects. In addition, studies at clonal level reveal a normal percentage of IL-2 producer T cell in aged individuals. In conclusion, our data suggest that the T cell in aged subjects are normal in number, but they have a decreased capacity of lymphokine production.

Alpha 1-acid glycoprotein (alpha 1-AGP) on the membrane of human lymphocytes: possible involvement in cellular activation

A glycoprotein termed alpha 1-acid glycoprotein (alpha 1-AGP) is a component of normal human serum; its concentration is often increased in several pathological disorders, including acute inflammation and cancer. Inhibitory effects of alpha 1-AGP on some in vitro T and B cell function assays have been reported but our recent data indicated that alpha 1-AGP is indeed a T cell mitogen at physiological concentrations. The present study was designed to investigate: (a) the relationship between this glycoprotein and two other glycoproteins of the T and B cell membrane, i.e. the T3 and Ia antigens; (b) the ability of lymphocytes to take up exogenous alpha 1-AGP; (c) the different expression of alpha 1-AGP on the T cell membrane upon different activation pathways, i.e., autologous non-T-cells (B cells and monocytes) phytohemagglutinin and anti-T3 monoclonal antibody (MAb) stimulations. The data reported herein show no competition at the membrane level between anti-alpha 1-AGP and anti-T3 or anti-Ia MAbs. In addition, (1) the lymphocytes were able to absorb alpha 1-AGP from the culture medium and (2) the expression of this glycoprotein was enhanced upon T cell stimulation (all three stimulants employed induced an increase of alpha 1-AGP positive T cells), thus suggesting a possible role of this glycoprotein in in vitro T cell activation.