J chain disease: A novel form of plasma cell dyscrasia

Abstract

Immunohistochemical staining of cells from the bone marrow of patients with plasma cell dyscrasias such as multiple myeloma usually reveals a variable proportion of cells that stain with both anti-heavy and anti-light chain reagents of one immunoglobulin isotype and one light chain type (e.g., IgG-K). In approximately 1% of patients, more than one immunoglobulin isotype may be found, usually in different cells. In other cases the bone marrow cells may produce only light or heavy chains (light or heavy chain diseases) or may not stain with either anti-heavy or -light chain reagents despite their plasma cell morphology and clinical manifestations of multiple myeloma. In contrast to cells from normal bone marrow, cells from patients with various gammopathies may contain J chain in addition to heavy and light chains, irrespective of the immunoglobulin isotype or light chain type produced [l-5]. The presence of J chain in immunoglobulin-producing cells from the bone marrow has been considered a useful marker to distinguish multiple myeloma from benign gammopathy; in the latter disorder the immunoglobulin-producing cells express J chain in a lower frequency than cells from patients with multiple myeloma [5]. In normal individuals, bone marrow cells are usually devoid of intracytoplasmic J chain [6]. The presence of J chain has also been revealed by immunohistochemical techniques in various B-cell lymphomas [7-lo] and is considered a possible marker of malignancy [7]. Furthermore, the Jchain-positive but immunoglobulin-negative cells were detected in three of 90 patients with high-grade lymphoma [9] and in Reed-Sternberg and Hodgkin cells in some [lo] but not other patients with Hodgkin’s disease [7,8]. In tissue samples from normal individuals, J chain is easily detectable in cells that produce polymeric IgM or IgA; secretory glands and mucosa-associated tissues such as mammary, salivary, and lacrimal glands, intestines, and nasal mucosa are particularly rich in J chain- and IgA- or IgM-producing cells [6,11,12]. While examining bone marrow specimens from 88 patients suspected of having a plasma cell dyscrasia or other immunoproliferative diseases by immunofluorescence technique, we observed that cells from four patients displayed unusual staining patterns: in one patient, numerous cells stained for IgG-K or J chain, with a few containing both IgG-K and J chain; in two patients, a few of the IgA- or IgG-containing cells stained for J chain, although most of the J chain-containing cells were negative with either heavy or light