Pulse labeling of small nuclear ribonucleoproteins in vivo reveals distinct patterns of antigen recognition by human autoimmune antibodies

D. E. Fisher, W. H. Reeves, G. E. Conner, G. Blobel, H. G. Kunkel

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Antibodies directed against small nuclear ribonucleoprotein (snRNP) particles are found in the Sm and RNP autoimmune sera from numerous patients with systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). These two reactivities differ in disease distribution as well as antigen specificity. Although sera from both of these autoimmune syndromes contain snRNP reactive antibodies, distinctions in antigen binding specificity have been difficult to define because of the particulate nature of the snRNP antigen. To overcome this problem, while retaining the antigen in a native state, cells were pulse-labeled with [35S]methionine for 8 min to generate radioactive snRNP proteins in forms reflecting incomplete de novo particle assembly. Immuno-precipitation of SnRNP antigen prepared in this manner revealed clearly distinct patterns of Sm and RNP immunorecognition. While Sm sera precipitated all eight labeled snRNP proteins, RNP antibodies precipitated only two of the eight. However, a brief pulse followed by periods of cold chase demonstrated that RNP sera can eventually coprecipitate all components of the complete particle. In addition to antibodies to the other six snRNP peptides, all Sm sera tested have been found to contain the RNP-like reactivity with snRNP proteins A and C. RNP reactivity with these two components is of particular interest because these proteins are unique in the metabolism of snRNPs. Defining and distinguishing the precise peptides recognized by Sm and RNP antibodies has helped to clarify the biochemical basis of the standard laboratory tests for these antigen reactivities.

Original languageEnglish (US)
Pages (from-to)3185-3189
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume81
Issue number10 I
DOIs
StatePublished - 1984
Externally publishedYes

ASJC Scopus subject areas

  • General

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