Bone marrow T-cell subsets in patients with monoclonal gammopathies: correlation with clinical stage and disease status.

BACKGROUND AND OBJECTIVE The existence of an imbalance in T-cell subpopulations in patients (pts) affected by monoclonal gammopathies (MG) has been well established. This imbalance might be correlated with different control of plasma cell growth and, particularly in MM, with the severity of the disease. The aim of this study was to verify whether the alteration of the T lymphocyte subsets in bone marrow correlates with the diagnosis, clinical status and disease phase in patients with monoclonal gammopathies. METHODS We performed a study on bone marrow (BM) T-cell subsets in 49 multiple myelomas (MM) and in 17 monoclonal gammopathies of uncertain significance (MGUS), using as controls 20 BM aspirates from normal subjects. RESULTS The percentages of BM CD4 cells in MM pts at onset were slightly lower than in controls and in MGUS pts, who showed normal percentages of CD4. The percentages of CD8 cells were lower than in controls in both MM and MGUS (p = 0.02 and p = 0.007, respectively), and consequently the CD4/CD8 ratios were significantly higher than in normal subjects (p = 0.01 and 0.008, respectively). Analysis of BM T-cell subpopulations in MM pts showed a progressive decrease in the percentage of CD4 cells from stage I to stage III (I vs III p = 0.008) and an increase in CD8 cells, although not statistically significant. The same trend was observed when the different phases of MM (onset, plateau, progression) were analyzed: a lower percentage of CD4 cells and an increase of CD8 cells characterized the advanced phases. Treatment did not seem to alter significantly the distribution of T-cell subsets in MM patients. INTERPRETATION AND CONCLUSIONS The imbalance in T-cell involving the bone marrow lymphocytic populations that exist in MG is somewhat different in MGUS and MM. In MM patients this disturbance is related to the disease stages and phases, reflecting an important role for T-cell subsets in tumor cell control.