Immunological Typing and IgG Subclass Distribution in Plasma Cell Dyscrasias Diagnosed Among Jordanian Patients

Objective: This study was carried out to determine types of plasma cell dyscrasias among Jordanian patients according to immunoglobulin class and whenever applicable subclass and determine characteristics of plasma cell dyscrasias with respect to demographic data and laboratory findings. Methods: One hundred patients with different types of plasma cell dyscrasias newly diagnosed at the hematology and oncology clinics of four major hospitals in Amman; Al-Basheer Hospital, King Hussein Medical Center, King Hussein Cancer Center and the Jordan University Hospital during the period between March 2001 and October 2002 were included in the study. Serum specimens were assayed by three different methods; serum protein electrophoresis for the detection of monoclonal gammopathies, immunofixation electrophoresis for the identification of immunoglobulin class and a sandwich type ELISA to determine IgG subclasses. Results: Results of this study demonstrated that 65 cases (65%) of plasma cell dyscrasias were Multiple Myeloma (MM), 29 (29%) were Monoclonal Gammopath of Unknown Significance (MGUS), 5(5%) were Solitary Bone Plasmacytoma (SBP) and one case (1%) was Waldenstrom's Macroglobulinemia (WM). The overall frequency distribution of paraprotein classes of the 65 multiple myeloma cases was: 48 (74%) IgG, 12 (18%) IgA and 5 (8%) light chain, whereas the distribution of IgG subclasses in multiple myeloma was 34 (70.8%) IgG1, 4 (8.4%) IgG2, 2 (4.2 (%IgG3, 1(2%)IgG4 and 7(14.5%) belonged to more than one subclass. In the 29 cases of monoclonal gammopathy of unknown significance, the frequency was 17(59%) for IgG, 7 (24%) for IgA and 5(17%) for IgM , whereas the distribution of IgG subclasses was 10 (58.7%) for IgG1, 6 (35.4%) for IgG2 and 1 (5.9%) for IgG3. All types of plasma cell dyscrasias were significantly more common among male patients than female patients. Conclusions: Multiple Myoloma is the most common type of plasma cell dyscrasia encountered in Jordan and the frequency distribution of paraprotein classes and IgG subclasses among Jordanian patients with plasma cell dyscrasias parallel internationally reported normal serum concentration for them. Moreover, more than one IgG subclass may be found in IgG gammopathies.