25 research outputs found
Chronic polyarthritis as the first manifestation of juvenile systemic lupus erythematosus patients
Overlapping juvenile idiopathic arthritis and systemic lupus erythematosus: a case report
In vitro studies on the Fc-receptor function of mononuclear phagocytes in rheumatoid arthritis: relation between the Fc-receptor blockade and the concanavalin A-binding capacity of autologous immunoglobulin G
The Fc-receptor (Fc-R) function of monocytes isolated from 19 control subjects
and from 30 patients presenting with a rheumatoid arthritis (RA) was assessed in
vitro by a classical rosette assay using IgG-coated sheep red blood cells. In RA
patients, the percentage of monocytes forming rosettes was significantly lower
than in controls (34.4 +/- 20.4 versus 67.4 +/- 4.5%; P less than 0.001). The
blockade observed was reversed by a prior trypsin treatment of RA monocytes, the
percentage of recovery being correlated with the IgG plasma levels. Besides, IgG
purified from the serum of four RA patients bound a mean of 7.3, 5.2, 1.6, and
1.6 times more than normal IgG did onto concanavalin A (Con A), peanut agglutinin
(PNA), phytohemagglutinin (PHA), and pokeweed mitogen (PWM), respectively.
Although similar amounts of 125I-labeled normal and RA IgG were bound to normal
monocytes, RA IgG inhibited more efficiently than normal IgG the Fc-R function of
normal monocytes, for all concentrations tested (10 to 100 micrograms/100
microliters). A prior treatment of RA IgG by alpha-mannosidase, but not by
beta-galactosidase, significantly reduced their inhibitory properties. The
incubation of monocytes with D-mannose or mannan reduced their capacity to form
rosettes. The percentage of monocytes forming rosettes in the presence of both
mannan and normal IgG was significantly lower than that measured in the presence
of normal IgG only. On the contrary, the rosetting capacity of monocytes in the
presence of both RA IgG and mannan was the same as that calculated in the
presence of RA IgG only. The inhibitory effect of RA IgG was not related to their
abnormal circular dichroism. Our data suggest that the greater ability of RA IgG
to block the Fc-R function of monocytes probably depends on the presence of a
greater number of accessible mannosyl residues on the glycosidic side chains
located in the Fc domain of the molecules