B Cell Receptors Of Chlamydophila Psittaci negative MALT Lymphomas Of The Ocular Adnexa Recognize Common Self-Antigens

• Published in: Blood 2013-11, Vol.122 (21), p.4266-4266
• Main Authors: Zhu, Daxing, Lu, Xiaoqing, Minden, Marcus Dühren-von, Bhatt, Shruti, Lossos, Chen, Chapman-Fredricks, Jennifer R., Veelken, Hendrik, Jumaa, Hassan, Lossos, Izidore S
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V122.21.4266.4266

Ocular adnexal mucosa associated lymphoid tissue lymphomas (OAMALTLs) are the most common lymphomas in the ocular adnexa. The etiology and pathogenesis of OAMALTLs are still controversial. Association with Chlamydophila (C.) psittaci infection demonstrates marked geographic differences. We have previously reported biased IGHV (IGHV4 family and IGHV4-34 gene) and IGKV (IGKV3-20) usage in C. psittaci-negative OAMALTLs (PLoS One. 2011;6(12):e29114; Am J Hematol.2013; 88:379). However, the identity and role of potential antigens (Ags) in OAMALTL pathogenesis are unknown. Herein we evaluated the reactivity of OAMALTLs derived B-cell receptors (BCRs) for bacterial and human antigens. IGHV and IGKV genes derived from 5 OAMALTLs (tumors 4726 and 4438 expressing IGHV4-34 with and without somatic mutations, respectively, both paired with IGKV3-20; tumor 4968 expressing IGHV3-30 and IGKV1-33; tumor 11274 expressing IGHV3-23 and IGKV3-20; and tumor 5334 expressing IGHV4-59 and IGKV3-1) were cloned into pAH6180 and pAN6714 plasmids, respectively. Irrespective of the original isotype, all recombinant antibodies (rAbs) representing tumor BCRs were expressed on a common IgG3 heavy chain backbone to facilitate the detection and comparability in reactivity assays and to ensure that differences in binding activity could be attributed to specific variable regions. rAbs were produced in HEK293T cells adapted to serum-free suspension cultures. rAbs did not react with bacterial proteins derived from lysates of Staphylococcus aureus, Salmonella enteridis and C. psittaci infected HeLa cells. The rAbs also did not react with I/i Ags. Rheumatoid factor (RF) enzyme-linked immunosorbent assay (ELISA) suggested that rAbs derived from tumors 4726, 4968, 5334, and 11274 exhibit rheumatoid factor activity. However, a competitive inhibition assay using increasing quantities of purified human IgG Fc fragment failed to block the reactivity, indicating non-specific RF reactivity. To test the rAbs for reactivity with self-antigens, the standard indirect immunofluorescence assay (IFA) using permeabilized human HEp-2 cells was performed. All tumor derived rAbs were reactive with HEp-2 cells and exhibited diverse staining patterns; predominantly cytoplasmic staining with rAbs 5334 and 4968 and combined nuclear and cytoplasmic staining with the others. We next examined tumor derived rAbs for polyreactivity based on the commonly used definition of reactivity with at least two of the following diver