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Biomedical subjects

I Gigli

Publications and source records attributed to I Gigli.

At least 19 recordsLinked to original sources
PubMed1992

Protoporphyrin and long-wave ultraviolet light modulate metabolic events in rat peritoneal mast cells.

We have previously shown that protoporphyrin (PP) plus long-wave ultraviolet light (UVA) has an inhibitory effect on the release of histamine from rat peritoneal mast cells in response to various stimuli, without compromising cell viability. In the present study, we observed that protoporphyrin at a noncytolytic dose (3 ng/ml) plus UVA irradiation (0.038 J/cm2) is also able to suppress prostaglandin D2 generation by rat peritoneal mast cells in response to calcium ionophore A23187, compound 48/80, or anti-IgE antibody by 64%, 92%, and 100%, respectively. Because of the participation of protein kinase C in stimulus-secretion coupling in mast cells, we also investigated the effect of PP plus UVA on the release of histamine induced by the protein kinase C activator, phorbol 12-myristate 13-acetate (PMA). PP plus UVA inhibited histamine release induced by PMA. The release of histamine induced by the synergistic combination of PMA (50 nM) and a low dose of calcium ionophore A23187 (0.1 microM) was also inhibited. PP plus UVA inhibited the release of histamine induced by the non-fluorescent calcium ionophore, 4-Br-A23187, by 47.8%, but had essentially no effect on changes in intracellular calcium induced by this stimulus. In contrast, both the release of histamine and changes in intracellular calcium stimulated by compound 48/80 were inhibited. We conclude from these results that PP plus UVA may affect both early and late biochemical events involved in mast cell mediator release.

Animals↗
PubMed1992

Expression and localization of proteins of the complement system in human skin.

The complement system participates in the immune recognition of foreign antigens, many of which may penetrate the skin by physical injury or transcutaneous adsorption. In this study, we examined the presence of complement components and complement regulatory proteins in the human skin and cultured human keratinocytes. Immunofluorescence studies showed C3, Factor B, decay accelerating factor, the C3b receptor (CR1), and C3d receptor (CR2), distributed among cells of the epidermis as well as on cultured keratinocytes. Immunoblot analysis of keratinocytes supernatants showed the presence of C3 with a molecular weight of approximately 180 kD. The decay accelerating factor was localized as previously reported on elastic fibers; additionally it was observed in the basement membrane zone. In situ hybridization studies suggest the expression of CR1 and CR2 mRNA in human epidermis. These results show the presence in the human epidermis of complement components that are capable of generating the initial C3 convertase of the alternative pathway. The presence of complement regulatory proteins could endow keratinocytes with immune functions such as the regulation of complement activation and endocytosis of C3 opsonized particles.

Antigens, CD↗
PubMed1990

Dual effects of protoporphyrin and long wave ultraviolet light on histamine release from rat peritoneal and cutaneous mast cells.

In this study we investigated the effects of long wave ultraviolet light (UVA) and various doses of protoporphyrin (PP) on the release of histamine from rat peritoneal and cutaneous mast cells. We also correlated these results with morphologic characteristics and viability of the cells. PP at a dose of 30 ng/ml plus UVA-induced negligible histamine release from rat peritoneal mast cells (RPMC), but was able to suppress the ability of the cells to release histamine in response to subsequent exposure to the calcium ionophore A23187, compound 48/80, or the combination of Ag and IgE. This functional change was associated with an increase in cell size, and cell lysis that gradually occurred during 24 h in culture. PP at a dose of 3 ng/ml plus UVA also significantly inhibited secretogogue-induced histamine release from rat peritoneal mast cells, but this dose was not associated with significant changes in morphology or viability. These various effects of PP plus UVA were also observed with mast cell preparations obtained by the enzymatic dispersion of rat skin. The suppression of secretogogue-induced histamine release in rat peritoneal mast cells treated with PP (3 ng/ml) and UVA could not be reversed by culturing the cells in the dark for 24 h in the absence of PP. Unlike the direct cytotoxic histamine releasing action of high doses of PP plus UVA, the suppressive effect of low PP doses could not be inhibited by catalase, but could be reduced by the absence of calcium. Our results indicate that PP plus UVA has dual effects on mast cells, apparently involving distinct mechanisms. This implies the possibility that PP and UVA at appropriate doses could be used in photochemotherapy of mast cell-mediated skin diseases.

Animals↗
PubMed1979

Modulation of the classical pathway C3 convertase by plasma proteins C4 binding protein and C3b inactivator.

We recently described the isolation from human serum of a serum protein (C4 binding protein) that functions as an essential cofactor for C3b inactivator in the proteolysis of fluid-phase C4b and to a much lesser extent, C3b. We show here the role of C4 binding protein in the formation and function of the classical pathway C3 convertase (C42). C4 binding protein interferes with the assembly of the membrane-bound C3 convertase of the classical pathway and accelerates the decay of C42 in a dose-dependent fashion. Its removal from serum by means of specific immune absorption promotes the vigorous consumption of C3 after addition of C1; this effect is abolished by reconstitution with purified C4 binding protein. Although C4 binding protein inhibits the hemolytic function of cell-bound C4b, we did not detect any change in the structure of C4b even after prolonged incubations of EAC14 with C4 binding protein. For this reason, and on the basis of studies of the time required for maximal reactivity (Tmax) of cellular intermediates generated in the presence of C4 binding protein and limited amounts of C2, we conclude that the effects of C4 binding protein are probably mediated by displacing C2a from specific binding sites on C4b. In addition, C4 binding protein enhances the cleavage by C3b inactivator of the alpha' chain of cell-bound C4b. When EAC14 cells were incubated with both control proteins, the Tmax of the cells was prolonged and the lysis was markedly diminished. We conclude that C4 binding protein and C3b inactivator control the C3 convertase of the classical pathway in a fashion similar to that described for beta 1H and C3b inactivator in the alternative pathway.

Animals↗
PubMed1978

Structural and functional differences between the H-2 controlled Ss and Slp proteins.

Based on functional and structural data, it is concluded that the Ss protein in the mouse expresses the activity of the fourth component of complement. Removal of the Ss, but not of Slp, antigen correlates with a high degree of significance (P less than 0.001) with decrease of C4 hemolytic activity. In phenotypically Slp negative mice the plasma/serum levels of Ss correlate with the C4 activity (P less than 0.001). Structurally, Ss is a 209,000-mol wt protein, consisting of three covalently linked polypeptide chains (alpha,beta,gamma). Treatment of Ss with C1 cleaves a 7,000-8,000-mol wt fragment from the alpha-chain. Slp is also a three chain covalently linked protein of 209,000 daltons, however its three chains differ in size from those of the Ss protein. Slp does not express hemolytic activity and its alpha-chain is not cleaved by C1.

Animals↗
PubMed1978

Human C4-binding protein. II. Role in proteolysis of C4b by C3b-inactivator.

We recently described the isolation from human serum of a high molecular weight protein with specific binding affinity for fluid-phase activated C4. We show here that the C4-binding protein (C4-Bp) functions as an essential cofactor in the proteolysis of C4b in the presence of C3b-inactivator (C3bINA). C4-bp, together with C3bINA, cleave the alpha'-chain of C4b into three fragments called alpha2, alpha3, and alpha4, with mol wt of 47,000, 25,000, and 17,000 daltons, respectively. The alpha2 fragment was dissociated from C4b without reduction, whereas the alpha3 and alpha4 fragments were disulfide bonded the other chains of C4b. The reaction did not occur when either C4-bp or C3bINA were omitted, nor in the presence of either protein in combination with beta1H. Native C4 was not affected by C3bINA aand C4-bp. C4b was not cleaved when incubated in serum of a patient with genetic deficiency of C3bINA. However, when purified C3bINA was added, the alpha'-chain of C4b was cleaved and fragments with the same molecular weight as alpha2, alpha3, and alpha4 were generated.

Carrier Proteins↗
PubMed1978

Human C4-binding protein. I. Isolation and characterization.

C4-binding protein (C4-bp), a new component of the complement system, was isolated from human plasma by precipitation with polyethyleneglycol, followed by chromatography on ion exchangers. C4-bp was identified on sodium dodecyl- sulfate polyacrylamide gel electrophoresis (SDS-PAGE) by two independent criteria: its ability to bind to C4b, and immunoprecipitation with a monospecificantiserum. Purified C4-bp is a 10.7 s glycoprotein. It consists of several disulfide bonded subunits of mol wt 70,000 daltons. Under nonreducing conditions, its mol wt has been estimated on SDS-PAGE as 540- 590,000 daltons. C4-bp moves as a slow B-globulin at pH 8.6 in the absence of free divalent cations, but when the buffers contain Ca(++)-lactate, C4-bp is a gamma globulin. Purified C4-bp binds to purified C4b. The reaction proceeds in the presence or absence of divalent cations and is not inhibited by diisopropylfluorophosphate. The C4b/C4-bp complexes have sedimentation coefficients between 15 and 17 s on sucrose gradient ultracentrifugation, and can be readily identified by crossed immunoelectrophoresis (CIE). The complexes move faster toward the anode than either protein. C4-bp is multivalent. Saturation is reached at molecular ratios of C4b/C4- bp of between 4 and 5. The interaction between C4b and C4-bp may complicate the electrophoretic patterns of these proteins in normal human serum, if the complement system is activated before or during the run. However, in EDTA-plasma, native C4 and C4-bp do not form stable complexes and can be identified in separate peaks after CIE.

Blood Protein Electrophoresis↗
PubMed1978

Hyperimmunoglobulin E syndrome.

A 24-year old woman had the major features of the hyperimmunoglobulin E syndrome: recurrent staphylococcal skin infections (from the age of 6 months), an extremely elevated serum immunoglobulin E level (25,000 units/ml), and defective neutrophil chemotaxis. This patient also had peripheral blood eosinophilia and cutaneous candidiasis. There was a family history of asthma, but the patient herself did not have a history of asthma or hay fever, and, on examination, had no evidence of atopic dermatitis. The patient has not had any systemic infections. Results of the skin biopsy showed dermal edema and a perivascular infiltrate with eosinophils and an increased number of mast cells. The clinical spectrum of the hyperimmunoglobulin E syndrome may include atopic dermatitis, mucocutaneous candidiasis, systemic infections, and/or the features of Job's syndrome.

Adolescent↗
PubMed1977

The isolation and structure of C4, the fourth component of human complement.

The fourth component of complement, C4, was isolated from human serum in good yield, and in confirmation of previous reports was shown to be formed from three peptide chains, alpha, beta and gamma, with apparent mol.wts. 90 000, 80 000 and 30 000 respectively. Preparative methods are described for the isolation of the three peptide chains and their amino acid analyses reported. Component C4 contains 7.0% carbohydrate, alpha-chain 8.6% and the beta-chain 5.6%. The N-terminal amino acid sequences are given for 12 residues of the alpha-chain, eight of the beta-chain and 19 of the gamma-chain.

Amino Acid Sequence↗
PubMed1977

The structure and enzymic activities of the C1r and C1s subcomponents of C1, the first component of human serum complement.

The subcomponents C1r and C1s and their activated forms C-1r and C-1s were each found to have mol.wts. in dissociating solvents of about 83000. The amino acid compositions of each were similar, but there were significant differences in the monosaccharide analyses of subcomponents C1r and C1s, whether activated or not. Subcomponents C1r and C1s have only one polypeptide chain, but subcomponents C-1r and C-1s each contain two peptide chains of approx. mol.wts. 56000 ("a" chain) and 27000 ("b" chain). The amino acid analyses of the "a" chains from each activated subcomponent are similar, as are those of the "b" chains. The N-terminal amino acid sequence of 29 residues of the C-1s "a" chain was determined, but the C-1r "a" chain has blocked N-terminal amino acid. The 20 N-terminal residues of both "b" chains are similar, but not identical, and both show obvious homology with other serine proteinases. The difference in polysaccharide content of the subcomponents C-1r and C-1s is most marked in the 'b' chains. When tested on synthetic amino acid esters, subcomponent C-1r hydrolysed both lysine and tyrosine ester bonds, but subcomponent C-1r did not hydrolyse any amino acid esters tested nor any protein substrate except subcomponent C1s. The lysine esterase activity of subcomponent C1s provides a rapid and sensitive assay of the subcomponent.

Amino Acid Sequence↗
PubMed1977

Graft-versus-host reaction. Cutaneous manifestations following bone marrow transplantation.

The distinctive cutaneous changes that occur in both the acute and chronic forms of the graft-vs-host reaction (GVHR) are described in two living patients in whom the GVHR developed after bone marrow transplantation for aplastic anemia. In the skin, the mild form of the acute GVHR is recognized as a subtle macular erythema, and the severe form appears as erythematous papules and violaceous macules with scale. Skin biopsy specimens in both of the acute forms show vacuolar alterations of the epidermal basal-cell layer with a perivenular infiltrate of lymphocytes. The chronic GVHR evolves from generalized scaling to diffuse areas of aclerotic and atrophic skin with a curious reticulated hyperpigmentation, ulcerations, and alopecia. Histopathologic study shows collagenization of the dermis that can be correlated with the clinical sclerodermoid changes. Owing to its visibility, the skin offers a unique opportunity for the early recognition of the GVHR.

Adult↗
PubMed1976

The unactivated form of the first component of human complement, C1.

The first component of complement, C1, was isolated unactivated from human serum by repeated additions of di-isopropyl phosphorofluoridate during isolation. The unactivated subcomponents were also isolated, and evidence is given that the three subcomponents C1q, C1r and C1s account wholly for the activity of component C1 in serum. No evidence could be found for a fourth subcomponent, C1t. The approximate molar proportions of the subcomponents in serum are C1q/C1r/C1s = 1:2:2. Optimum activity by haemolytic assay was found at approximate molar proportions C1q/C1r/C1s of 1:4:4. No activity was found when subcomponents were assayed singly or in pairs, except for subcomponents C1q and C1s, which in molar ratio 1:4 gave 15-20% of the activity of the mixture C1q + C1r + C1s. The proteolytic activity of the isolated subcomponent C1s varied according to the method of activation used. Subcomponents C1q + C1r + C1s and C1q + C1s in the presence of antibody-antigen aggregates were activated and inactivated simultaneously, showing a peak of activity and subsequent loss of activity. Both reactions are probably due to proteolysis, and analysis of the peptide bonds split will be necessary to distinguish these two phenomena.

Antigen-Antibody Complex↗
PubMed1976

Two distinct cellular patterns in cutaneous necrotizing angiitis.

Two distinct cellular patterns of necrotizing angiitis involving venules in skin of patients with clinically identical cutaneous lesions were appreciated by the 1 -mum-thick section technique. In those individuals with serum hypocomplementemia, there was a perivenular inflitrate composed predominantly of neutrophils with fibrin deposition and nuclear debris. In patients with normal serum complement levels, in addition to an infiltrate of neutrophils and fibrin deposition, perivenular lymphocytes in various stages of activation were prominent. In both patterns the venules and not the arterioles were affected, mast cells exhibited various degrees of hypogranulation, and basophils and eosinophils were recognized only rarely. Lesions of different clinical age obtained from one hypocomplelmentemic patient and one normocomplementemic patient exhibited consistent cellular patterns, as did a single crop of lesions biopsied twice, 24 hr apart, in a patient with hypocomplementemia. No patient with hypocomplementemia became normocomplementemic or vice versa with persistence of lesions.

Adult↗