Joint‐derived T cells in rheumatoid arthritis react with self‐immunoglobulin heavy chains or immunoglobulin‐binding proteins that copurify with immunoglobulin

摘要

AbstractRheumatoid arthritis patients were found to have CD4+T cells that proliferate in response to autologous synovial fluid and plasma. T cell clones and polyclonal T cell lines were found to respond to antigen(s) eluted from protein A Sepharose and anti‐human immunoglobulin (Ig) antibody Sepharose. The antigen(s) was further resolved to fractions that contained intact Ig or Ig heavy chain since the T cells responded to>100 kDa and 40‐‐60 kDa polypeptides derived from purified Ig under nonreducing and reducing conditions, respectively. These results indicated that the antigen(s) is either Ig heavy chain or Ig‐binding proteins that copurify with Ig and Ig subunits. Pepsin and papain digestion of the antigenic fractions eluted from protein A destroyed the T cell reactivity. Since most Fab regions are resistant to these enzymes, further analyses are required to localize the antigenic epitope(s). The presence of Ig‐ or Ig‐antigen complex‐reactive T cells in arthritic joints implies that B cells expressing anti‐Ig antibody (i.e.rheumatoid factor) may play an important role in antigen presentation to autor