A Comparative Study of Monoclonal Gammopathies and Immunoglobulin Levels in Japanese and United States Elderly

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Abstract
Objective: To define the prevalence of monoclonal immunoglobulin (Ig) proteins and quantitative serum immunoglobulin levels in elderly Japanese in comparison with elderly Caucasians as possible factors related to the reported lower incidence of multiple myeloma in elderly Japanese than in elderly Caucasians.Design: Survey studySetting: Community Center in Yokohama, Japan and Retirement Community in the United States.Participants: Convenience sample of community‐dwelling elderly subjects (age 63–95) presenting for health screening examinations in each setting. Frozen serum samples were obtained from routine screening from 146 consecutive Japanese subjects and 111 US subjects.Intervention: NoneMeasurements: Presence of monoclonal immunoglobulin protein determined by serum protein electrophoresis and immunofixation and quantitative Ig by laser nephelometry.Results: Four (2.7%) of the Japanese cohort had monoclonal gammopathies compared with 11 (10%) of the American cohort. Two of the monoclonal gammopathies were IgG Kappa and two were IgG Lambda. No cases of multiple monoclonal gammopathy were identified in the Japanese group, compared with 25% of the monoclonal gammopathies in the American group. The mean quantitative serum IgG level for the Japanese group was 1,685 ± 520 mg/dL versus 1,118 ± 402 mg/dL for the American group; mean quantitative IgA levels were 283 ± 116 mg/dL versus 226 ± 116 mg/ dL (P < 0.001). Albumin levels were normal in both populations, suggesting that there was not an increase in occult inflammatory disorders in the Japanese population.Conclusion: The low prevalence of monoclonal gammopathy in elderly Japanese is consistent with the reported lower frequency of multiple myeloma. The reason for the higher quantitative immunoglobulin levels in this population is unclear. Further cross‐cultural investigation is warranted to explore the genetic influences on altered immune regulation with aging.