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J K Naama

Publications and source records attributed to J K Naama.

8 recordsLinked to original sources
PubMed1986

Circulating immune complexes associated with decreased complement-mediated inhibition of immune precipitation in sera from patients with bacterial endocarditis.

The sera of patients with bacterial endocarditis frequently contain high levels of circulating immune complexes. In in vitro assays these sera have been shown to be deficient in the complement mediated inhibition of immune precipitation (immune complex solubilization) although C3 and C4 levels were often normal. The deficiency is due to the presence of a factor which also inhibits the ability of normal serum to solubilize immune complexes. This inhibitor is possibly rheumatoid factor which is frequently detected in endocarditis. Serial studies on 16 patients showed the levels of immune complexes, the ability to prevent immune precipitation and rheumatoid factor to correlate with disease activity. The similarity of the findings to those in rheumatoid arthritis are discussed.

Adult↗
PubMed1985

Prevention of immune precipitation by purified components of the alternative pathway.

The role of the alternative pathway in complement-mediated prevention of immune precipitation has been investigated by the use of BSA-anti-BSA immune complex (IC) purified components. For immune precipitation to be prevented all six alternative pathway components (C3, factors B D, P, H and I) were required. In the absence of one or both of the control proteins H and I, excessive fluid phase turnover of C3 occurred with precipitation of IC. Kinetic studies showed that in the presence of the control proteins, an initial phase of precipitation occurred, and was followed by a phase of resolubilization of IC. When the efficiency of classical and alternative pathways in the prevention of immune precipitation was compared it was found that the classical pathway proteins were more effective than the alternative pathway components. A reaction mixture containing the components of both pathways was no better than the classical pathway protein alone. 125I-C3 was bound to IC which had been rendered soluble in the presence of classical or alternative pathway components. A molar ratio of two molecules C3b:five molecules IgG was calculated. Other complement components which were bound to IC which had been formed in the presence of serum were C1q, C4, C2, C3, C5, P and H. Factors B and I were not detected. Our findings suggest that the alternative pathway is of secondary importance to the classical pathway in the prevention of immune precipitation.

Antigen-Antibody Complex↗
PubMed1984

Inhibition of immune precipitation in rheumatic disease. A clinical and laboratory study.

Antigen-antibody complexes formed in the presence of serum do not precipitate. This complement-dependent function is impaired in approximately half of all patients with seropositive rheumatoid arthritis (RA) but not in patients with other chronic inflammatory arthropathies. As patients with seropositive RA have normal or elevated serum complement levels, this findings suggests that an inhibitor is present in the serum of these patients. Although degree of impairment of solubilization is correlated with rheumatoid factor (RF) titre, decreases in RF titre in patients receiving gold therapy were not always accompanied by improvement of the solubilization process. Thus we can conclude that impaired solubilization is related to, but may be distinct form, RF. Impaired solubilization was associated with the presence of subcutaneous nodules, but not with other systemic features of RA. Thus this phenomenon may be of pathogenetic importance.

Antigen-Antibody Complex↗
PubMed1984

Prevention of immune precipitation by purified classical pathway complement components.

The role of the classical pathway of complement in the prevention of immune precipitation has been investigated using purified complement components and immune complexes (IC) consisting of rabbit anti-BSA and BSA. C1 reduced the rate of immune precipitation. As C1q, EDTA treated C1 or C1-inhibitor treated C1 were unable to retard the precipitation of IC, it was concluded that the intact C1 molecule was required for this function. Use of phenylmethylsulphonyl fluoride and benzamidine showed that the enzymatic site on C1 was not required for this activity. C4 and C2 did not affect immune precipitation significantly when C1 was present at the concentrations present in serum. When C3 was added to C1, C4 and C2 precipitation of IC did not occur. These data demonstrate that classical pathway activation alone is sufficient for the prevention of immune precipitation.

Antigen-Antibody Complex↗
PubMed1984

IgM-RF prevents complement-mediated inhibition of immune precipitation.

Rheumatoid arthritis (RA) serum inhibits complement-mediated inhibition of immune precipitation (solubilization). We have isolated inhibitory activity from RA sera and shown that it is a property of IgM-rheumatoid factor (IgM-RF) and, to a lesser extent, IgG-RF.

Antigen-Antibody Complex↗
PubMed1983

Complement-mediated inhibition of immune precipitation in patients with immune complex diseases.

The ability of human sera to prevent the precipitation of antigen-antibody complexes has been investigated. The early complement components including C3 are required for optimal prevention of immune precipitation, whereas the later components are not required. The sera of 36 of 75 patients with seropositive rheumatoid arthritis (RA), 14 of 32 with SLE and four of 17 with glomerulonephritis exhibited reduced capacities to prevent immune precipitation. In contrast sera from patients with seronegative RA, ankylosing spondylitis, psoriatic arthritis or degenerative joint disease were normal in this respect. In SLE and GN sera hypocomplementaemia was frequently associated but not always with failure to prevent immune precipitation, whereas only a small proportion of the patients with seropositive RA and reduced capacity to retain complexes in a soluble form were hypocomplementaemic. Thus the failure of sera to prevent the precipitation of antigen-antibody complexes is not always associated with hypocomplementaemia.

Antigen-Antibody Complex↗
PubMed1983

Inhibition of complement-mediated solubilization of antigen-antibody complexes by sera from patients with rheumatoid arthritis.

Sera and synovial fluids from patients with seropositive rheumatoid arthritis inhibit the ability of normal serum to prevent immune precipitation. Sera from patients with seronegative forms of arthritis contain little inhibitory activity. Studies of the mechanism of action of the inhibitor show that it reduces C4 consumption by antigen-antibody complexes. These findings suggest that the binding of C1 to complexes or activation of C1 is impaired. The possibility that the inhibitory activity may be mediated by rheumatoid factor is discussed. As inhibitory activity is more prevalent and of a higher level in patients with extra-articular features, it is possible that it may play a pathogenetic role.

Antigen-Antibody Complex↗