Correlation between Ig-synthesis patterns and lymphoma classification

Abstract

This study examines the link between free immunoglobulin (Ig) light-chain (LC) secretion and the developmental stage of the neoplastic B-cell of origin in B-cell lymphomas. The Kiel developmental scheme for lymphoma classification has been used to define the tumour-cell populations. Twenty-four B-cell lymphomas have been studied. In the small-lymphocytic lymphoma group, secreted Ig consisted of LC exclusively or in excess over heavy-chain (HC). Lymphomas of follicular-centre-cell origin, considered to be from cells further along the normal B-cell differentiation pathway, can be divided into centroblasts or centrocytes according to their histological appearance in tissue sections. Centroblastic lymphomas exhibited strong surface IgM or IgG expression, and the secretion of whole Ig was higher than by cells from the small-lymphocytic lymphomas. Synthesis of HC and LC was balanced in these cultures, both intracellularly and in secreted material. The centrocytic lymphomas comprised a functionally more heterogeneous group, the SIg varied in intensity and was of surface IgM, D or G. Likewise Ig synthesis was variable in quantity and composition, some cases secreting LC exclusively while others, including the cases expressing SIgG, secreted balanced HC and LC. In the Kiel classification centrocytes are considered to be more mature than centroblasts. Our data suggest that centrocytic lymphomas are heterogeneous in origin, some preceding and others following centroblasts in the B-cell maturation sequence. These data are discussed in relation to current concepts of B-cell maturation and lymphoma histology.