Lymphocyte subsets in the peripheral blood of patients with multiple myeloma and benign monoclonal gammopathy

Potential of NK cells in multiple Myeloma therapy

Introduction: Despite rapid advances in myeloma treatment with the development of new drugs, curative therapies remain elusive. Relapsed/refractory disease related to progressive dysregulation of immune system and acquired genetic abnormalities continues to be a major obstacle in achieving cure. Immune-based therapy harnessing the host defense mechanism of natural killer (NK) cells is a promising avenue in the treatment of myeloma. Areas covered: Here, we discuss the biology and cytotoxic activity of NK cells and the potential role of these innate immune cells in defense against cancer and specifically multiple myeloma. We also discuss the role of NK cells in the anti-myeloma effects of autologous and allogeneic stem cell transplantation, various novel drugs, and treatment modalities such as chimeric antigen receptor therapy. Immune evasion, either directly or indirectly involving NK cell dysfunction, may be a key and under-recognized mechanism in myeloma progression. We reviewed extensive literature identified using the keywords immunotherapy, natural killer cells, and multiple myeloma. Expert opinion: Novel treatment approaches in myeloma utilizing the immunomodulatory and cytotoxic properties of NK cells to eradicate resistant and quiescent clones could pave the way for potentially curative interventions.

Immunoregulatory mechanisms in multiple myeloma

This review presents current experimental data regarding immunologic changes associated with multiple myeloma (Table 1). It is becoming increasingly clear that some of the immunologic changes are host responses to the malignant plasma cell clone and monoclonal immunoglobulin. In the last 2 to 3 years an anti-idiotypic response has been clearly documented, and cells expressing CD16 and soluble CD16 have been identified as modulators of myeloma cell growth and differentiation. Abnormalities in B- and T-cell differentiation have been observed, most consistently the deficiency of T4 helper cells. Differences in the immunologic changes point to the provocative hypothesis that, in MGUS and the initial stages of myeloma, immunologic responses play an important role in controlling proliferation of the malignant clone, and at some point the system is overwhelmed or fails, leading to an overt or more aggressive disease. The quest is to understand the genesis of the autoregulatory circuits operative in myeloma. Novel strategies for immunotherapy in management of myeloma will arise through improved understanding of host immune response and its cause-and-effect relationship with myeloma cell growth.

Peripheral blood lymphocyte subsets in multiple myeloma and monoclonal gammopathy of undetermined significance

Peripheral blood lymphocyte subsets were analysed by flow cytometry and compared among 43 patients with untreated multiple myeloma (MM), 16 patients with monoclonal gammopathy of undetermined significance (MGUS) and 26 controls. The age and sex distributions of the patients and controls were comparable, which is important, since in the controls there was a significant effect of age and/or sex on the number of CD3+, CD57+, CD8+57+, CD16+ and CD3-56+ lymphocyte subsets, and on the CD4+/CD8+ and CD4+Leu-8+/CD4+ ratios. In MM, the number of CD8+ and CD57+ cells and the CD4+/CD8+ ratio were related to the clinical stage. The number of CD20+, CD3+, CD4+, CD16+ and CD3-56+ cells and the CD3+/CD20+ ratio were significantly different in MM patients compared to age- and sex-matched controls as was the number of CD3+ and CD4+ cells of MGUS patients compared to controls. Further, there were significant differences in the CD3+/CD20+ ratio between MM and MGUS patients and between stage I MM and MGUS. The role of peripheral blood lymphocyte subsets in differentiating monoclonal gammopathies merits further study.

Comparative analysis of immunodeficiency in patients with monoclonal gammopathy of undetermined significance and patients with untreated multiple myeloma

The objectives of this study were firstly, to compare the immunophenotype of patients with monoclonal gammopathy of undetermined significance (MGUS) with that of patients with newly diagnosed, untreated multiple myeloma (Unt. MM). Our second objective was to determine which variables might distinguish patients with MGUS and early MM. The CD4/CD8 ratio in both patient groups differed significantly from normal as a result of a decrease in the proportion of CD4+ cells. Similarly, surface immunoglobulin-positive (Ig+) B cells were significantly reduced in both groups. Also, some impairment of Ig secretion was observed. An in vitro specificity study of B cells showed an enriched proportion of B cells specific for tetanus toxoid (which may be indicative of enrichment for memory B cells) in both MGUS and Unt. MM patients. Further to this, in MM patients but not in MGUS patients, there was an enriched proportion of B cells specific for determinants on the F(ab')2 fragment of Ig. This suggests an anomalous auto-immune reactivity to polyclonal Ig molecules. In one of the two patients studied, who progressed from MGUS to MM, disease progression was accompanied by an increase in this anti-Ig reactivity. In both patients there was a decrease in CD4/CD8 ratio.

Selective loss of CD4+ CD45R+ T cells in peripheral blood of multiple myeloma patients

The phenotypic distribution of T-lymphocyte subsets in peripheral blood from multiple myeloma (MM) patients shows a reduced proportion of CD4+ cells and a normal proportion of CD8+ cells. The decrease in CD4+ cells could be due to a random process, with all types of CD4+ cells being equally affected, or it could reflect a nonrandom process with selected subsets preferentially reduced. In order to distinguish between these possibilities, double immunofluorescence analysis was performed on blood samples from patients with MM, patients with monoclonal gammopathy of unknown significance (MGUS), and age-matched normal donors, using monoclonal anti-CD4 or anti-CD8 paired with antibodies to the common leukocyte marker Lp220 (CD45R) or 4B4 (CDw29). Normal peripheral blood lymphocytes (PBL) include two phenotypically and functionally distinct CD4+-cell subsets, identified as CD4+ Lp220+ 4B4- and CD4+ Lp220-4B4+, whereas the majority of CD8+ cells expresses Lp220 (70-85%). MM patients had a highly significant selective reduction of the CD4+ Lp220+ subset compared with normal controls (P less than 0.001). Although the percentage of CD4+ Lp220- cells was also reduced in some MM patients relative to normal donors, most of MM patients had an elevated Lp220-/Lp220+ ratio of CD4+ cells (P less than 0.001). The proportion of the two CD8+ subsets was also markedly abnormal. In the set of patients studied the abnormalities within the CD4+ and CD8+ lymphocytes were exclusive to patients with MM since patients with MGUS had normal proportion of CD4+ and CD8+ subsets.

Monoclonal antibody-defined T lymphocyte subpopulations in monoclonal gammapathy of undetermined significance

We used monoclonal antibodies of the OK series to study T lymphocyte subpopulations in 55 patients with monoclonal gammapathy of undetermined significance (MGUS) and in 40 healthy control subjects, with the aim to investigate if alterations in T lymphocyte subpopulations occur also in MGUS. Mean OKT3+ and OKT8+ cell counts were higher (p less than 0.01 and p less than 0.001, respectively) and the mean OKT4/OKT8 ratio was lower (p less than 0.02) in MGUS patients than in the control subjects. MGUS with the IgM-type monoclonal immunoglobulin (IgM-MGUS) showed the most evident derangement of T lymphocyte subpopulations, i.e., a significant increase of OKT8+ cells and a significant reduction of the OKT4/OKT8 ratio. OKT4+ and OKT8+ cells were significantly increased in patients with high paraprotein concentration (above 16 g/l). Our data suggest that alterations of T lymphocytes are present in MGUS, and that they are similar to those observed in malignant lymphoproliferative disorders.

Secretions of anti-myelin-associated glycoprotein antibodies by B cells from patients with neuropathy and nonmalignant monoclonal gammopathy

Four patients with peripheral neuropathy and nonmalignant monoclonal gammopathy with anti-myelin-associated glycoprotein (MAG) antibodies were studied to determine whether secretion of anti-MAG IgM antibodies by B cells was autonomous, or whether the monoclonal B cells were responsive to T cells. Secretion of anti-MAG IgM by isolated B cells was stimulated by the addition of increasing numbers of pokeweed mitogen (PWM)-activated autologous OKT4+ helper T cells in all four patients. Secretion of anti-MAG IgM by peripheral blood lymphocytes was dependent on the ratio of OKT4+ T helper cells to OKT8+ T suppressor/cytotoxic cells. In three patients with an OKT4+ to OKT8+ T-cell ratio of 2:1, PWM activation stimulated secretion of anti-MAG IgM; in one patient with an OKT4+ to OKT8+ ratio of 1:2, activation by PWM suppressed anti-MAG IgM secretion. These studies suggest that the monoclonal B cells that secrete anti-MAG IgM are responsive to regulatory T cells.

Diagnostic value of the concentration of M-component in initial classification of monoclonal gammopathy

The diagnostic value of the concentration of a serum M-component in initial classification of monoclonal gammopathy into malignant monoclonal gammopathy (MMG) and monoclonal gammopathy of undetermined significance (MGUS) was evaluated in 315 consecutive individuals with IgG, IgA or IgM type M-components. The final diagnosis was MMG in 84 and MGUS in 231 patients. Serum concentration was significantly highest in MMG, but for all 3 kinds of M-components, overlapping serum concentrations between MMG and MGUS were found. Highest efficiency was reached with a serum concentration of 30.2 g/l for IgG, 26.6 g/l for IgA and 22.7 g/l for IgM. Using these values, an initial correct classification was achieved in 0.90 of IgG M-components, in 0.91 of IgA M-components and in 0.79 of IgM M-components. Normal levels of uninvolved immunoglobulins were found to point strongly to MGUS.

T-cell subsets in malignant lymphomas and monoclonal gammopathies

159 patients with malignant lymphomas or monoclonal gammopathies were investigated for lymphocytes and their subsets using conventional surface markers and a panel of monoclonal antibodies. In untreated patients with Hodgkin's disease, non-Hodgkin lymphomas and multiple myeloma, (MM) a reduction of T-cells and especially of the "helper/inducer" subset (OKT4+) was found to be a common phenomenon. The major abnormalities occurred in advanced stages of disease. Patients previously treated by chemo- and/or radiotherapy had a further decrease of T-cells, whereas the loss of OKT4+ cells was more pronounced than that of the "suppressor/cytotoxic" lymphocytes (OKT8+). The alterations of lymphocyte subsets persisted even in long-term remitters. Comparing the lymphocyte subsets in MM and benign monoclonal gammopathies (BMG), patients with BMG showed a significant reduction in OKT8+ cells, whereas the OKT4+ population was within normal range, resulting in a significant elevation of the OKT4/OKT8-ratio compared to the controls and untreated multiple myeloma.

Imbalances of T-cell subsets in monoclonal gammopathies

In 42 patients with untreated or treated multiple myeloma (MM) or benign monoclonal gammopathy (BMG) the lymphocytes and T lymphocyte subsets were determined by monoclonal antibodies and other surface markers. In untreated MM, the T cells (1077/microliters vs 1439/microliters, P less than 0.01) and especially the OKT4+ lymphocytes (700/microliters vs 950/microliters, P less than 0.05) were significantly reduced compared with a control group. The OKT8+ cells were slightly but not significantly decreased. In previously treated MM, the loss of T cells was more pronounced than in the untreated group and was primarily caused by a further reduction of OKT4+ cells. Patients with BMG revealed decreased OKT8+ lymphocytes (304/microliters vs 502/microliters, P less than 0.001), whereas the OKT4+ cells were within the normal range. Therefore, the OKT4/OKT8 ratio was significantly elevated compared with that in untreated MM patients and normal controls (3.31 vs 2.06 vs 2.13; P less than 0.005). To sum up, in MM the results revealed a reduction of T cells, mainly of OKT4+ cells, which is intensified by chemotherapy and persists even after a long therapy-free interval. The different findings of T cell subsets in BMG and MM may be a helpful criterion to differentiate between BMG and MM.