Autoimmune Manifestations in Patients With Waldenström Macroglobulinemia

Aberrant Extrafollicular B Cells, Immune Dysfunction, Myeloid Inflammation, and MyD88-Mutant Progenitors Precede Waldenstrom Macroglobulinemia

Waldenstrom macroglobulinemia (WM) and its precursor IgM gammopathy are distinct disorders characterized by clonal mature IgM-expressing B-cell outgrowth in the bone marrow. Here, we show by high-dimensional single-cell immunogenomic profiling of patient samples that these disorders originate in the setting of global B-cell compartment alterations, characterized by expansion of genomically aberrant extrafollicular B cells of the nonmalignant clonotype. Alterations in the immune microenvironment preceding malignant clonal expansion include myeloid inflammation and naïve B- and T-cell depletion. Host response to these early lesions involves clone-specific T-cell immunity that may include MYD88 mutation-specific responses. Hematopoietic progenitors carry the oncogenic MYD88 mutations characteristic of the malignant WM clone. These data support a model for WM pathogenesis wherein oncogenic alterations and signaling in progenitors, myeloid inflammation, and global alterations in extrafollicular B cells create the milieu promoting extranodal pattern of growth in differentiated malignant cells.

SIGNIFICANCE

These data provide evidence that growth of the malignant clone in WM is preceded by expansion of extrafollicular B cells, myeloid inflammation, and immune dysfunction in the preneoplastic phase. These changes may be related in part to MYD88 oncogenic signaling in pre-B progenitor cells and suggest a novel model for WM pathogenesis. This article is highlighted in the In This Issue feature, p. 549.

Monoclonal B-cell Lymphocytosis Exacerbated by Prednisolone Therapy for Dermatomyositis

Lymphoproliferative diseases have been associated with various autoimmune diseases. We experienced a case of non-chronic lymphocytic leukemia type monoclonal B-cell lymphocytosis (MBL) that was exacerbated by increasing prednisolone for dermatomyositis and then improved by decreasing the dosage. Because MBL is difficult to diagnose, cases like ours may not be rare. These findings will facilitate our understanding of the mechanism underlying lymphoproliferative diseases and autoimmune diseases.

Multiple cystic lung lesions and autoimmune thrombocytopaenia developing after chemotherapy for pulmonary indolent B-cell lymphoma with plasmacytic differentiation

Among lung malignancies, primary pulmonary lymphoma is rare and many of them are indolent B-cell lymphomas. We describe a case of primary pulmonary indolent B-cell lymphoma with plasmacytic differentiation, which exacerbated with the manifestation of macroglobulinaemia and was successfully treated using chemotherapy. The patient subsequently developed pulmonary cysts and thrombocytopaenia due to autoimmune pathology and was successfully treated using prednisolone. This case suggests that in indolent B-cell lymphoma with plasmacytic differentiation, immunoglobulin M level should be carefully followed even if it is within the normal range at lymphoma onset. Additionally, new cystic pulmonary infiltrates that develop during the post-treatment follow-up of an indolent pulmonary B-cell lymphoma may indicate pulmonary lymphoma recurrence, but there is also a possibility of an immunological complication.

Refractory IgG Warm Autoimmune Hemolytic Anemia Treated with Eculizumab: A Novel Application of Anticomplement Therapy

Warm autoimmune hemolytic anemia (wAIHA) is the most common form of AIHA, with corticosteroids in first-line treatment resulting in a 60-80% response rate. Atypical wAIHA and IgG plus complement mediated disease have a higher treatment failure rate and higher recurrence rate. We report a case of severe wAIHA secondary to Waldenström macroglobulinemia with life threatening intravascular hemolysis refractory to prednisone, rituximab, splenectomy, and plasmapheresis. A four-week treatment of eculizumab in this heavily pretreated patient resulted in a sustained increase in hemoglobin and transfusion independence, suggesting a role for complement inhibition in refractory wAIHA.