Host-related immunodeficiency in the development of multiple myeloma.

Host-related immunodeficiency is known to play a role in the development of multiple myeloma (MM) from its precursor conditions (monoclonal gammopathy of undetermined significance, MGUS, smoldering multiple myeloma, SMM). In order to understand the underlying immune changes in this process, we characterized immune patterns from MGUS to SMM to MM. We further sought to identify potential novel immune biomarkers that may predict progression of SMM to MM. We characterized patterns of circulating lymphocytes in 181 patients using multiparametric flow cytometry. We found decreased B- (p = .0003), increased T- (p = .037) and unaltered NK cell proportions from MGUS to SMM to MM. To gain insights into functional variability, we further characterized immunophenotypic lymphocyte subsets, which uncovered differences in CD57 subsets. Specifically, we found that SMM patients who eventually progressed to MM showed decreased proportions of CD57-CD56 + (p = .0061) and CD57-CD16 + (p = .035) lymphocyte subsets. We thus report novel data characterizing the nature of host-related immunodeficiency in the development of MM. We show sequential changes in lymphocyte subsets from MGUS to SMM to MM. We further suggest that CD57 subsets may serve as potential markers of progression from SMM to MM. Our findings support the study of lymphocyte subsets in the search for immune biomarkers. Such markers could provide clinical guidance in managing myeloma precursor disease.