Clinical significance of serum properdin levels and properdin deposition in the dermal-epidermal junction in systemic lupus erythematosus

61 biopsies of normal skin from the deltoid area and lesional skin from various sites from 48 patients with systemic lupus erythematosus (SLE) were studied for the presence of properdin, C3, C4, and immunoglobulins (IgG, IgM, and IgA) in the dermal-epidermal junction (DEJ) using direct and indirect immunofluorescence. Properdin was present in 50% of normal and 40% of lesional skins. Properdin was present without C4 in only 2 of 38 nonlesional skin biopsies and in only 2 of 20 lesions. There was no significant difference in incidence of deposition of any of the six proteins studied between nonlesional and lesional skin. The frequency of deposition of each of the proteins correlated with clinical disease activity. The presence of proteins in the DEJ did not correlate with the presence of active renal disease at the time of biopsy nor with previously documented active nephritis. In addition, no other single clinical manifestation correlated with the presence of DEJ deposition of any protein studied. IgA was not demonstrated in the DEJ of nonlesional skin of 16 patients in remission and was present in 7 of 23 patients with active disease (P less than 0.05). Deposition of properdin in lesional skin correlated with the presence of extracutaneous disease activity (P less than 0.05). Analysis of serologic studies on serum obtained at the time of biopsy revealed a statistically significant correlation between C4 and C3 (r = 0.67). This correlation was stronger than that between properdin and C4 (r = 0.37). Titer of antinuclear antibody and percent of DNA binding correlated better with C4 levels than with properdin levels. Serum properdin levels were significantly lower in patients with active disease than in those in remission (P less than 0.05). Serum properdin levels were significantly lower in patients with properdin deposits in lesional skin than in those without properdin deposits. The data suggest that both alternative and classical pathways are activated in patients with clinically active SLE.

Mechanisms of activation of the properdin system. Studies on properdin electrophoretic mobility in agarose activation of the alternative pathway

The electrophoretic mobility of properdin in agarose with and without EDTA examined in sera from normal subjects and from patients with mesangiocapillary glomerulonephritis, systemic lupus erythematosus, rapidly progressive glomerulonephritis, mesangial IgG-IgA disease, minimal change glomerulonephritis and partial lipodystrophy. In 'EDTA agarose", the properdin arc of normal serum was always cathodal (gamma), whereas in non-EDTA agarose it was always (beta), indicating that agarose activated properdin with its consequent conversion from a cathodal to an anodal form. Using this change in the mobility of properdin to investigate activation of the properdin system, it was found that the lower the C3 concentration of diseased sera, the less able were they to support properdin conversion by non-EDTA agarose. This relationship we interpret as a manifestation of the requirement of an intact C3b feedback pathway for properdin activation. This view was supported experimentally by (i) decreasing ability of non-EDTA agarose to shift properdin mobility in normal serum as it was progressively depleted of components of the alternative pathway by cobra venom factor, C3 nehritic factor or Mg2+, and (ii) the inability of non-EDTA agarose to shift properdin in sera depleted of C3 or factor B, and in serum deficient in C3. The report of other workers that activated properdin causes generation of C3b, coupled with our finding that properdin activation depends on the C3b feedback, indicates that a system exists in which activation of the C3b feedback cycle allows activation of properdin, allowing in turn further amplification of the C3b feedback. That the anodal form of properdin may be a property of activated properdin was shown by our observations that properdin eluted from zymosan was anodal and activated, and that the properdin in the supernatant normal serum incubated with inulin was anodal.

Properdin factor B (glycine-rich beta-glycoprotein or C3 proactivator)-polymorphism: genetic and biochemical aspects. First application to paternity cases

Determination of genetic properdin factor B(Bf) polymorphism was carried out in immunofixation electrophoresis. Genetics of factor B were also studied after ageing, conversion with cobra venom and neuraminidase. In population studies the distribution of factor B in a West German population of 1245 non-related individuals was found to be: Bf F 2.73%, Bf FS 28.43%, Bf S 65.38%. Rare phenotypes (F 1F,F 1S, FS 1, SS 1) were seen in 3.46%. In addition a new variant, designated F1.6S, was observed. The application of factor B polymorphism to 68 paternity cases is discussed.

Immunologic phenomena in herpes gestationis

Immunofluorescence findings are of diagnostic significance in herpes gestationis. The studies in two cases demonstrated some complement components (chiefly C3 and C4, but no C(1q)), without immunoglobulins at the basement membrane zone and with no circulating anti BMZ antibodies. In one case IgG were found at the BM zone in one biopsy specimen, but were not demonstrable in several other biopsies. The IF findings seem to indicate both the alternate and classical pathways of complement activation, and speak in favor of a relation between herpes gestationis and bullous pemphigoid, in which sometimes the immunoglobulins are also not demonstrable and the immunofluorescent pattern is very much like that of herpes gestationis.

Complement breakdown products in plasma from patients with systemic lupus erythematosus and patients with membranoproliferative or other glomerulonephritis

A dynamic estimation of the involvement of the complement system in various diseases was obtained by the direct quantitation of breakdown products of C3 and of properdin factor B. The methods used were based, first on the separation of native and fragmented molecules according to their molecular size through a precipitation with polyethylene glycol and, secondly, on an immunochemical quantitation, using specific antisera for the major antigens of C3 and factor B. The sensitivity and the specificity of these methods were demonstrated by activation of complement in vitro with generation of C3 and factor B fragments. A clinical investigation was carried out in 41 patients with systemic lupus erythematosus (SLE), 31 with membranoproliferative glomerulonephritis (MPGN), 26 with other types of glomerulonephritis, and 6 with severe alcoholic cirrhosis of the liver. The following observations were made: (a) an elevated plasma level of C3d fragment of C3 was found in 68% of SLE patients, in 87% of MPGN patients, in 62% of patients with other hypocomplementemic nephritis, and in 15% of those with normocomplementemic nephritis, but in only 33% of patients with liver cirrhosis and very low levels of C3; (b) a significant difference was observed between the levels of C3 obtained with either anti-"native" C3 or anti-C3c sera for immunochemical quantitation, in patients with SLE or MPGN, indicating the presence of "altered" or fragmented C3 in plasma; (c) an elevated plasma level of Ba fragment of properdin factor B was found in 46% of SLE patients, in 67% of MPGN patients, in 50% of patients with other hypocomplementemic nephritis, and in 9% of patients with normocomplementemic nephritis, while the level of properdin factor B was only slightly decreased in these diseases; (d) in SLE and MPGN there was an inverse correlation between the levels of C3d and Ba and the level of C3 in plasma. The level of these fragments was directly correlated with the clinical manifestations of SLE; (e) some patients with a normal C3 level exhibited an elevated plasma concentration of C3 and factor B fragments, suggesting the coexistence of an increased synthesis with a hypercatabolism of complement components. Therefore, the quantitation of complement breakdown products by simple immunochemical methods provides additional information concerning the involvement of complement in disease and new features for the evaluation of the intensity of immune reactions during immune complex diseases.

Depressed synovial fluid levels of properdin and properdin factor B in patients with rheumatoid arthritis

Two proteins in the properdin system, properdin and factor B, and complement components C4 and C3 were measured by radial immunodiffusion in serums and synovial fluids from 21 patients with rheumatoid arthritis (RA) and positive tests for rheumatoid factor, 9 patients with seronegative RA, and 10 with degenerative joint disease. In addition to depressions of synovial fluid C4 which correlated with lowered C3 in seropositive RA, consistent with activation of the classic pathway, low synovial fluid levels of factor B and properdin in seropositive RA indicate intraarticular activation of the properdin pathway as well.

Studies on the effect of Fenchlorphos on postirradiation changes of serum proteins and nucleic acids content in rat liver

The effect of Fenchlorphos on postirradiation changes of serum protein levels and nucleic acid content in rat liver were investigated. It was found that this compound significantly decreases postirradiation changes in serum proteins, properdin level and nucleic acid content in rat liver. An important role of these phenomena in radioprotective action of Fenchlorphos is suggested.

Proerdin and recurrent macroscopic haematuria

Kidney biopsies from ten children with recurrent macroscopic haematuria, showed mesangial deposition of IgG, IgA and complement. Eight of these ten biopsies also showed disposition of properdin, a basic euglobulin intimately involved in the alternate pathway of complement activation. Serum haemolytic complement activity was normal in the eight patients tested. Incubation of the serum at 4 degrees C for 24 dours did not result in any change in complement activity. Theses data suggest that the mesangial inflammatory process in these patients may be medicated in part by the alternate pathway of complement activation and that the mechanism is activated locally.

Studies of the alternate pathway in chelated serum

Activation of the alternate pathway in chelated serum by cobra venom factor (Co F), endotoxin of Escherichia coli, inulin, and zymosan was studied by immunoelectroprhoresis, radial immunodiffusion, and complement fixation tests. In serum chelated by 10 mM EGTA and 10 mM MgCl-2 (10 mM MgEGTA) activation by the classical pathway was blocked, but activation of C3PA and C3 occurred normally. By radial immunodiffusion assay, consumption of C3 and properdin was demonstrated to be similar to consumption in nonchelated sera. By immunoelectrophoresis, C3PA and C3 were shown to be activated by CoF in serum chelated with 6 mM but not with 10 mM EGTA without added Mg++. Inulin and endotoxin did not result in activation of either C3PA or C3, while C3PA but not C3 was activated by zymosan in the presence of 10 mM EGTA without Mg++ added. Consumption of properdin and C3, measured by radial immunodiffusion, was inhibited by 6 to 10 mM EGTA following activation by inulin, but not following activation by zymosan. The usefulness of 10 mM MgEGTA-chelated serum for the selective investigation of the alternate pathway in chemotaxis was demonstrated.

Alternative C3 pathway activiation in pneumococcal glomerulonephritis

Glomerulonephritis following pneumococcal infection has been observed, but possible immunopathologic mechanisms have not been adequately explored. Multiple serologic studies as well as light, immunofluorescence and electron microscopic evaluation of kidney biopsy tissue from a 4 year old girl with pneumococcal glomerulonephritis were performed. Clinical studies at the onset of the disease showed normal serum C3 and C4 levels (third and fourth components of complement) with progression to selective C3 hypocomplementemia from days 2 to 58. A serum factor capable of breaking down C3 in normal human serum was present during the period of maximum C3 hypocomplementemia. Renal glomerular histology revealed a mesangial proliferative glomerulonephritis. Glomerular bound C3 and type 14 pneumococcal antigen were associated with similar, but less extensive, deposits of properdin. Minimal immunoglobulin M (IgM) and C4 were seen, but immunoglobulin G (IgG) and fibrinogen were absent. Ultrastructurally, subepithelial "humps" and intramembranous electron dense deposits were noted. It is hypothesized that the pneumococcal polysaccharide can activate the alternate complement pathway and may be responsible for a limited course of glomerulonephritis.

Human necrotizing vasculitis: immunoglobulins and complement in vessel walls of cutaneous lesions and normal skin

Immunoglobulins and C3 were detected by immunofluorescence in the blood vessel walls of biopsies of clinically normal skin in patients with active necrotizing vasculitis. Of the 13 patients studied, 9 had C3 and 6 of these had IgM or IgA in biopsies of lesions of vasculitis. In adjacent clinically normal skin, 7 patients had C3 and 3 of these also had IgM or IgA. These findings support the hypothesis that immunoglobulins and complement are present in vessels of some patients prior to chemotaxis of polymorphonuclear leukocytes and the resulting inflammatory purpuric lesions so characteristic of necrotizing vasculitis.

Activation of the properdin pathway of complement in patients with gram-negative bacteremia

To determine the pathway used for activation of complement component C3, serum levels of components C1, C4, C2, C3, C5, C6, and C9 and two properdin factors, properdin and factor B, were measured in 42 patients with gram-negative bacteremia, in 19 of whom shock subsequently developed. Mean levels of the classical components C1, C4, and C2 in bacteremic patients in whom shock subsequently developed did not differ significantly (p greater than 0.05) from those of patients with uncomplicated bacteremia. Levels of properdin, factor B and C3, C5, C6, and C9 were significantly (p less than 0.05) decreased in patients with shock in comparison with those with uncomplicated bacteremia. Taken together, these findings are consistent with activation of C3 and the terminal complement sequence, C5-C9, occurring primarily by the properdin pathway, in patients with gram-negative bacteremia eventuating in shock. Biologically active products released during activation of C3-C9 may contribute to the development of shock.