Molecular Characterization of the Ro/SS-A Autoantigens

AbstractMolecular techniques have recently revealed that there are several immunologically distinct Ro/SS-A antigens. Three genes encoding putative Ro/SS-A protein antigens with calculated masses of 46, 52, and 60 kD have been isolated. The encoded amino acid sequence of each is quite dissimilar. The 46-kD antigen is calreticulin (CR), a highly conserved calcium-binding protein that resides predominately in the endoplasmic reticulum where it may be involved in protein assembly. Although CR has recently been confirmed to be a new human rheumatic disease-associated autoantigen, its relationship to the other components of the Ro/SS-A ribonucleoprotein has become somewhat controversial owing predominately to the fact that recombinant forms of calreticulin have not displayed the same pattern of autoantibody reactivity possesse by the native form of this protein.The 52-kD antigen most likely resides in the nucleus and may be involved in the regulation of gene expression. The cellular location and function of the 60-kD antigen is uncertain but studies indicate that it is a RNA-binding protein.The 46- and 60-kD antigens share homology with foreign polypeptides, suggesting that an immune response initially directed against a foreign protein may give rise to the autoimmune response directed at cross-reacting self proteins

Organizing pneumonia following treatment with pembrolizumab for metastatic malignant melanoma – A case report

Pembrolizumab is a monoclonal antibody against the programmed cell death 1 (PD-1) receptor, and is widely used for the treatment of various malignancies, most commonly malignant melanoma. Here we report the first documented and pathology proven case of Organizing Pneumonia complicating treatment with Pembrolizumab. This was a man who presented with a dense lung consolidation four months following treatment with Pembrolizumab. A thorough microbiological workup was negative and his findings did not improve with broad spectrum anti-microbial treatment. Transbronchial biopsy revealed organizing pneumonia, and treatment with cortico-steroids resulted in complete resolution of clinical and radiological disease. This report highlights the importance of recognizing immune related adverse events, specifically pulmonary inflammation, in patients receiving treatment with novel immune-modulating agents