Chest
Volume 74, Issue 3, September 1978, Pages 261-264
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Immune Complexes in Sarcoidosis: A Correlation with Activity and Duration of Disease

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Samples of serum from patients with sarcoidosis were examined for the presence of immune complexes, using the Raji cell line. An indirect immunofluorescent technique was used to detect the binding of immune complexes to the complement receptors of Raji cells. Preliminary studies indicated that the method was sensitive and specific We studied 44 patients with sarcoidosis who were separable into the following three distinct clinical groups: (1) acute disease (one year or less); (2) chronic active disease (five years or more); and (3) resolved disease (five years or more). In the 26 patients with acute disease, 12 had circulating immune complexes; immune complexes were present in two of the ten patients with chronic active disease. In contrast, immune complexes were absent in patients with resolved disease and normal control subjects. In patients with active disease, there was no apparent correlation between the presence of immune complexes and the stage of disease; however, immune complexes were present in five of the 11 patients with extrapulmonary disease, in seven of 12 patients with elevated concentrations of γ-gtobulin, and in four of five of those patients with autoantibodies to lymphocytes.

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Subjects

Samples of serum from patients and control subjects were obtained from peripheral venous blood and were kept at −20°C or −70°C until tested. In all patients the diagnosis of sarcoidosis was based on clinical findings supplemented by biopsy of either skin or lymph node. Classification of the stage of the disease was in accord with the following standard criteria: stage 1, hilar adenopathy without parenchymal infiltrates; stage 2, hilar adenopathy associated with pulmonary parenchymal

Methodologic Considerations

The results of this study confirm previous observations3 that the Raji cell line, may be used to detect immune complexes by a fluorescent technique; however, as observed,3 it was first necessary to block the Fc receptor of the Raji cell line to prevent passive absorption of IgG, which results in unacceptably high background fluorescence. Prior incubation of Raji cells with human IgG, followed by treatment with F (ab') 2 fragments to human IgG, eliminated background fluorescence. Specific

Discussion

We7 have previously shown that some patients with acute disease have cold-reactive autoantibodies to lymphocytes. In the present study, four of the five patients whose sera contained cytotoxic autoantibodies to lymphocytes also had immune complexes. This raises the possibility that the immune complexes in these patients may actually represent antibodies directed to determinants of the Raji cell line; however, several lines of evidence argue against this possibility. First, in these patients,

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Manuscript received December 20; revision accepted February 9.

Supported by Specialized Center of Research grant HL-15061 from the National Heart and Lung Institute.

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