AbstractAnalysis of serum immunoglobulins from patients suffering from autoimmune disease has shown that pathogenically relevant autoantibodies directed at organ specific antigens are light chain restricted, i.e., they are entirely lambda or kappa type in a given patient.1–3Furthermore, plasma cells involved at tissue level in the production of such antibodies, for example in Graves' disease, have also been shown to express a marked light chain bias as judged immunohistologically.4On the basis of these findings, a study was conducted to determine the light chain status of tissue plasma cell infiltrates associated with Sjögren's disease, a known autoimmune disease. Of the six cases examined, all six showed a marked lambda light chain bias, with two patients exhibiting a monotypic plasma cell infiltrate of IgA, lambda isotype. The significance of the overall observations is discussed in the context of other examples of light chain restricted B‐cell responses and the generally increased incidence of benign and malignant B‐cell neoplasia in autoimmune d