Abnormal function of B lymphocytes from peripheral blood of multiple myeloma patients. Lack of correlation between the number of cells potentially able to secrete immunoglobulin M and serum immunoglobulin M levels

Negative impact of immunoparesis in response to anti-SARS-CoV-2 mRNA vaccination of patients with multiple myeloma

Multiple myeloma reduces cellular and humoral immunity. Optimal prediction of antibody response to anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine in patients with MM and related disorders is essential to prevent coronavirus disease 2019 (COVID-19) during the SARS-CoV-2 pandemic. This study analyzed the humoral response to the anti-SARS-CoV-2 messenger ribonucleic acid (mRNA) vaccine and its associated factor in 83 patients from June to November 2021 at seven member institutions of the Kyoto Clinical Hematology Study Group. SARS-CoV-2 neutralizing antibody (nAb) was measured from 12 to 210 days. The result revealed that 40 (48.2%) patients with MM and 59 (100%) healthy controls became seropositive after vaccination. Receiver operating characteristic curve analysis identified serum immunoglobulin (Ig) M of > 18 mg/dL at vaccination as the optimal threshold level associated with seropositivity in the whole cohort. Moreover, the multivariate analysis identified serum IgM of > 18 mg/dL as the independent predictor for a favorable response. Serum IgA level was positively associated with vaccine response in a sub-cohort. Our findings indicate a significant association between immunoparesis and impaired humoral response against mRNA vaccination, including that against SARS-CoV-2, and that serum non-M-protein Ig levels can serve as surrogate biomarkers of nAb production ability.

Dissecting the multiple myeloma-bone microenvironment reveals new therapeutic opportunities

Multiple myeloma is a plasma cell skeletal malignancy. While therapeutic agents such as bortezomib and lenalidomide have significantly improved overall survival, the disease is currently incurable with the emergence of drug resistance limiting the efficacy of chemotherapeutic strategies. Failure to cure the disease is in part due to the underlying genetic heterogeneity of the cancer. Myeloma progression is critically dependent on the surrounding microenvironment. Defining the interactions between myeloma cells and the more genetically stable hematopoietic and mesenchymal components of the bone microenvironment is critical for the development of new therapeutic targets. In this review, we discuss recent advances in our understanding of how microenvironmental elements contribute to myeloma progression and, therapeutically, how those elements can or are currently being targeted in a bid to eradicate the disease.

Longitudinal analysis of tetanus- and influenza-specific IgG antibodies in myeloma patients

BACKGROUND

Multiple myeloma (MM) and its therapies may induce a severely compromised humoral immunity. We have performed a longitudinal analysis of IgG-antibody responses against influenza virus (FLU) and tetanus toxoid (TT) as surrogate markers for the B cell-mediated immunity in MM patients.

METHODS

1094 serum samples of 190 MM patients and samples from 100 healthy donors were analyzed by ELISA for FLU- and TT-specific antibodies.

RESULTS

MM patients evidenced lower levels of FLU- and TT-specific antibodies than healthy controls (P < 0.001). Immunoreactivity decreased with progressing disease and worsening clinical status. Levels of FLU- and TT-specific antibodies increased shortly (0-6 months) after alloSCT (P < 0.001), a time-period during which intravenous immunoglobulin (IVIG) is routinely applied. Thereafter, antibody concentrations declined and remained suppressed for 3 years in the case of FLU-specific and for more than 5 years in the case of TT-specific antibodies.

CONCLUSIONS

We found that MM is associated with a profound disease- and therapy-related immunosuppression, which is compensated for a few months after alloSCT, most likely by application of IVIG. This and the differences regarding the recovery of anti-FLU and anti-TT antibody titers during the following years need to be taken into account for optimizing IVIG application and immunization after alloSCT.

Multiple Myeloma Includes Phenotypically Defined Subsets of Clonotypic CD20+ B Cells that Persist During Treatment with Rituximab

Potential progenitor B cell compartments in multiple myeloma (MM) are clinically important. MM B cells and some circulating MM plasma cells express CD20, predicting their clearance by treatment with anti-CD20. Here we describe two types of clonotypic CD20+ B cell in peripheral blood of myeloma patients, identified by their expression of CD19 and CD20 epitopes, their expression of CD45RA and their light scatter properties. Thus, the circulating component of the MM clone includes at least two distinct CD19+ CD20+ B cell compartments, as well as CD138+ CD20+ plasma cells. To determine whether either or both B cell subsets and the CD20+ plasma cell subset were depleted by anti-CD20 therapy, they were evaluated before, during and after treatment of patients with rituximab (anti-CD20), followed by quantifying B cell subsets over a 5 month period during and after treatment. Overall, all three types of circulating B lineage cells persist despite treatment with rituximab. The inability of rituximab to prolong survival in MM may result from this failure to deplete CD20+ B and plasma cells in MM.

Erythropoietin treatment in advanced multiple myeloma is associated with improved immunological functions: could it be beneficial in early disease?

Erythropoietin (Epo) is the main growth regulator of red blood cells, and recombinant human erythropoietin (rHuEpo) is thus used in clinical practice for the treatment of anaemia, primarily in kidney disease and cancer. rHuEpo treatment was found to be associated with prolonged survival of multiple myeloma (MM) patients. This clinical observation was then supported by studies on murine myeloma models. It thus appeared that rHuEpo had an anti-myeloma effect, causally related to an immunomodulatory function of rHuEpo. The present study investigated whether rHuEpo-treated MM patients acquire improved immunological functions. Treatment with rHuEpo, prescribed for anaemia that occurs in advanced disease, was associated with effects on a variety of immunological parameters and functions. This was expressed in an actual normalisation of the CD4:CD8 cell ratio, enhanced T cell phytohaemagglutinin-mediated activation and proliferation potential, T cell expression of the costimulatory CD28 and inhibitory CTLA-4 molecules, as well as reduced interleukin-6 serum values to normal levels. Furthermore, it was demonstrated that immunological abnormalities manifest in patients even in the early stages of MM. Our findings thus suggest that rHuEpo treatment might be effective in the early stages of MM, before anaemia develops. It is expected that this would boost the immune system, consequently achieving an anti-myeloma function; affecting disease progression and improving the prognosis.

Drug resistance in multiple myeloma: novel therapeutic targets within the malignant clone

Myeloma is incurable because the malignant stem cell is not eradicated by treatment. Thus, identification of the malignant hierarchy of B lineage cells in myeloma is required to identify potentially generative components and to evaluate their drug resistance properties. BM plasma cells are usually depleted by chemotherapy, but clonotypic B cells survive melphalan/prednisone as well as combination chemotherapy. In vitro, circulating and bone marrow-localized myeloma plasma cells show defective drug export, despite their phenotypic expression of P-glycoprotein, the mdr1 gene product. In contrast to plasma cells, circulating myeloma clonotypic B cells exhibit very efficient drug export. This suggests that circulating clonotypic MM B cells comprise a reservoir of drug resistant disease in myeloma although their stem cell potential remains to be confirmed. The malignant clone in each myeloma patient is defined by a unique IgH VDJ gene rearrangement. Using methods that exclude the possibility that a frequent but non-malignant clone has inadvertently been identified, and after confirming that the sequence identified is expressed by nearly all bone marrow plasma cells, we show that the drug resistant set of myeloma B cells is clonally related to the malignant plasma cells in myeloma. Clonotypic MM B cells survive chemotherapy, persist during clinically defined "minimal residual disease" and remain after autologous transplantation. Thus their malignant status is an important consideration. If malignant, they must be considered in the design of therapy. If non-malignant, they would be expected to have minimal impact on the disease process. A variety of evidence provides strong support for the view that clonotypic drug resistant B cells are malignant and may include the generative compartment of myeloma. The P-gp+ set of clonotypic B cells is extensively DNA aneuploid, an attribute of malignancy. All clonotypic B cells overexpress RHAMM, a novel oncogene involved in malignant spread. Finally, the population of clonotypic B cells lacks intraclonal heterogeneity. Since intraclonal heterogeneity is driven by the response to antigens, its absence in these cells indicates that they are no longer antigen-responsive. Since antigen-independent clonal expansion is characteristic of lymphoid malignancies, these observations provide further proof that clonotypic B cells in myeloma are malignant. Thus, the drug resistance of these cells is highly relevant to understanding why myeloma remains incurable despite the initial chemosensitivity of most bone marrow plasma cells.

A High Frequency of Circulating B Cells Share Clonotypic Ig Heavy-Chain VDJ Rearrangements With Autologous Bone Marrow Plasma Cells in Multiple Myeloma, as Measured by Single-Cell and In Situ Reverse Transcriptase-Polymerase Chain Reaction

In multiple myeloma (MM), the VDJ rearrangement of the immunoglobulin heavy chain expressed by MM plasma cells provides a unique clonotypic marker. Although clonotypic MM cells have been found in the circulation, their number has been controversial. Our objective was to provide direct evidence, using single-cell assays, for the frequency of clonotypic cells in blood of 18 MM patients, and to confirm their identity as B cells. The clonotypic Ig heavy-chain (IgH) VDJ was determined from single plasma cells using consensus reverse transcriptase-polymerase chain reaction (RT-PCR), subcloning, and sequencing. For all patients, using patient-specific primers, clonotypic transcripts were amplified from 10 or more individual plasma cells. Using in situ RT-PCR, for all patients greater than 80% of plasma cells were found to be clonotypic. Three separate methods, RT-PCR, single-cell RT-PCR, and in situ RT-PCR, were used to analyze clonotypic cells in peripheral blood mononuclear cells (PBMC) from MM patients. Sequencing of the IgH transcripts expressed by individual cells obtained by limiting dilution of freshly isolated PBMC from a MM patient showed that all B cells expressed an identical CDR3. This intraclonal homogeneity indicates an escape from antigenic-selection, characteristic of malignant B cells. For this patient, the frequency of clonotypic PBMC, about 25%, was comparable to the number of PBMC B cells (34%). Because the PBMC included less than 1% plasma cells, virtually all clonotypic PBMC must be B cells. Using single-cell RT-PCR, clonotypic IgH transcripts were identified in individual sorted B cells from blood. To accurately quantify the number of clonotypic B cells, sorted B cells derived from 18 MM patients (36 samples) and 18 healthy donors (53 samples) were analyzed using in situ RT-PCR with patient-specific primers. Clonotypic transcripts were not detectable among normal B cells. For the 18 MM patients, a mean of 66% ± 4% (SE) of blood B cells were clonotypic (range, 9% to 95%), with mean absolute number of 0.15 ± .02 × 109/L blood. Over time in individual patients, conventional chemotherapy transiently decreased circulating clonotypic B cells. Their numbers were increased in granulocyte colony-stimulating factor (G-CSF)– mobilized blood of one patient. However, clonotypic B cells of a one patient became undetectable after allogeneic transplant, correlating with complete remission. Although contributions to MM spread and progression is likely, their malignant status and impact has yet to be clarified. Their high frequency in the blood, and their resistence to conventional chemotherapy suggests that the number of circulating clonotypic cells should be clinically monitored, and that therapeutic targeting of these B cells may benefit myeloma patients.

© 1998 by The American Society of Hematology.

A High Frequency of Circulating B Cells Share Clonotypic Ig Heavy-Chain VDJ Rearrangements With Autologous Bone Marrow Plasma Cells in Multiple Myeloma, as Measured by Single-Cell and In Situ Reverse Transcriptase-Polymerase Chain Reaction

In multiple myeloma (MM), the VDJ rearrangement of the immunoglobulin heavy chain expressed by MM plasma cells provides a unique clonotypic marker. Although clonotypic MM cells have been found in the circulation, their number has been controversial. Our objective was to provide direct evidence, using single-cell assays, for the frequency of clonotypic cells in blood of 18 MM patients, and to confirm their identity as B cells. The clonotypic Ig heavy-chain (IgH) VDJ was determined from single plasma cells using consensus reverse transcriptase-polymerase chain reaction (RT-PCR), subcloning, and sequencing. For all patients, using patient-specific primers, clonotypic transcripts were amplified from 10 or more individual plasma cells. Using in situ RT-PCR, for all patients greater than 80% of plasma cells were found to be clonotypic. Three separate methods, RT-PCR, single-cell RT-PCR, and in situ RT-PCR, were used to analyze clonotypic cells in peripheral blood mononuclear cells (PBMC) from MM patients. Sequencing of the IgH transcripts expressed by individual cells obtained by limiting dilution of freshly isolated PBMC from a MM patient showed that all B cells expressed an identical CDR3. This intraclonal homogeneity indicates an escape from antigenic-selection, characteristic of malignant B cells. For this patient, the frequency of clonotypic PBMC, about 25%, was comparable to the number of PBMC B cells (34%). Because the PBMC included less than 1% plasma cells, virtually all clonotypic PBMC must be B cells. Using single-cell RT-PCR, clonotypic IgH transcripts were identified in individual sorted B cells from blood. To accurately quantify the number of clonotypic B cells, sorted B cells derived from 18 MM patients (36 samples) and 18 healthy donors (53 samples) were analyzed using in situ RT-PCR with patient-specific primers. Clonotypic transcripts were not detectable among normal B cells. For the 18 MM patients, a mean of 66% ± 4% (SE) of blood B cells were clonotypic (range, 9% to 95%), with mean absolute number of 0.15 ± .02 × 109/L blood. Over time in individual patients, conventional chemotherapy transiently decreased circulating clonotypic B cells. Their numbers were increased in granulocyte colony-stimulating factor (G-CSF)– mobilized blood of one patient. However, clonotypic B cells of a one patient became undetectable after allogeneic transplant, correlating with complete remission. Although contributions to MM spread and progression is likely, their malignant status and impact has yet to be clarified. Their high frequency in the blood, and their resistence to conventional chemotherapy suggests that the number of circulating clonotypic cells should be clinically monitored, and that therapeutic targeting of these B cells may benefit myeloma patients.

© 1998 by The American Society of Hematology.

CD8+/CD57 cells and apoptosis suppress T-cell functions in multiple myeloma

The aim of this study was to evaluate the role of CD8+/CD57+ lymphocytes in the immune dysregulation of multiple myeloma (MM). Cytofluorimetry of peripheral blood lymphocytes (PBL) purified from 39 MM patients showed an inverse relationship between the percentage of CD8+/CD57+ cells and CD4/CD8 ratio. Analysis of their activation antigens revealed that they were prevalently HLA-DR+ and Fas+. Removal of CD8+/CD57+ cells from MM PBL significantly improved cell proliferation and pokeweed mitogen (PWM)-induced polyclonal Ig production in vitro, whereas the addition of supernatants from patients' CD8+/CD57+ cell cultures to normal PBL suppressed both the PWM-driven Ig synthesis and the proliferative rate of stimulated PBL, supporting the contention that CD8+/CD57+ cells release in vitro an inhibitory factor that is directly involved in T-cell regulatory function. However, since the proliferative recovery of PWM- and phytohaemagglutinin (PHA)-stimulated MM PBL in the absence of CD8+/CD57+ lymphocytes was only partial, a dysregulated activation-induced apoptosis was anticipated. In fact, patients' PBL displayed an increased susceptibility to apoptosis and this was significantly enhanced after PWM and, even more, after PHA stimulation. Analysis of CD57 antigen expression on apoptotic or viable cells demonstrated a substantial defect of apoptosis in the CD8+/CD57+ population. Our results indicate that both the immunosuppressive effect of CD8+/CD57+ cells and the enhanced susceptibility to apoptosis of PBL could be involved in the pathogenesis of the immunodeficiency observed in this disease.

Interleukin-4 and tumour necrosis factor-alpha produce non isotype specific partial differentiation of peripheral blood B-cells in myeloma

In a previous study, culture of peripheral blood mononuclear cells (PBMC) from myeloma patients with interleukin(IL)-4 and tumour necrosis factor(TNF)-alpha resulted in the appearance of clonal plasma cells, thus suggesting the presence of circulating myeloma cell precursors in the peripheral blood. Using the same cytokine combination, we cultured PBMC and purified peripheral blood B-cells from myeloma patients. In nearly all cases, partial differentiation of B-cells occurred but, similarly to results for normal controls, both kappa and lambda light chain (L.C.) cytoplasmic positive lymphoid and lymphoplasmacytoid cells were detected rather than clonal plasma cells. These results suggest that IL-4 and TNF-alpha cause partial differentiation of residual normal polyclonal B-cells rather than of circulating myeloma cell precursors in the peripheral blood of myeloma patients.

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.

Circulating clonotypic B cells in the biology of multiple myeloma: speculations on the origin of myeloma

The population of circulating B cells in myeloma patients includes an apparently large but variable subset with the IgH VDJ rearrangement diagnostic for the malignant clone of plasma cells in individual myeloma patients. Although the biological significance is at present unknown, it is likely that they include both malignant and non-malignant clonal relatives of the myeloma plasma cells. This article presents speculations on the significance of these cells in the origin of myeloma and the relationship between monoclonal gammopathy of undetermined significance (MGUS) and frank myeloma. MGUS appears to represent the establishment of clonal dominance probably by a chronically antigen-stimulated B cell clone. It seems likely that malignant transformation event(s) occurring in a clonal daughter cell give rise to myeloma. If correct, this implies that in a myeloma patient, non-malignant antigen-responsive B cells expressing the patient-specific IgH rearrangement coexist in the circulation and probably all lymphoid tissues, with their malignant antigen-independent relatives. However, the significance one attributes to the clonotypic B cells detected in the blood of myeloma patients depends in part on the view one takes of the progression from MGUS to myeloma. An alternative perspective is that MGUS represents a dormant state of malignancy held in check by controlled apoptosis, arrested cell cycling, and/or by immunoregulatory networks. Although lacking in experimental support, if this interpretation were correct, myeloma would occur when the regulatory mechanisms fail, allowing uncontrolled malignant cell renewal. This alternative view would imply that the majority of circulating clonotypic B cells might be malignant. Thus, an analysis of the biology of these clonotypic circulating B cells, with an emphasis on measures of malignancy, is likely to shed considerable light on the events underlying myeloma genesis, progression and spread.

Autoregulatory circuits in myeloma. Tumor cell cytotoxicity mediated by soluble CD16

BACKGROUND

Multiple myeloma remains an incurable malignancy due to marked resistance of the tumor to standard doses of chemotherapy. Treatment approaches, using chemotherapeutic dose escalation and hematopoietic stem cell support have resulted in significant augmentation of tumor mass reduction such that complete remissions are effected in approximately 50% of patients. These remissions are however, often not durable. In the setting of minimal residual disease, therefore, adjunctive immunotherapy may be useful.

METHODS

Peripheral blood mononuclear cells were studied from 28 untreated patients with multiple myeloma (MM). Mononuclear cell CD16 (FcR gamma III) expression was determined by flow cytometry. The effect of lymphocyte-derived soluble CD16, isolated by affinity chromatography, on MM cell growth and differentiation was assessed. MM cell proliferation, viability, immunoglobulin production and gene expression was studied.

RESULTS

Data are presented indicating that cells expressing CD16 are increased in untreated patients with IgG-secreting myeloma. The predominant phenotype of these cells is CD8+ or CD56+. These CD16+ cells can produce a soluble form of the Fc receptor (sFcR, sCD16) that can bind to surface Ig on cultured human IgG-secreting myeloma cells and effect suppression of tumor cell growth and Ig secretion. This effector function is accompanied by concomitant suppression of c-myc as well as IgH and IgL gene transcription. Finally, prolonged exposure to sCD16 causes myeloma tumor cell cytolysis.

CONCLUSIONS

sCD16 and possibly other soluble FcR are candidate molecules for adjunctive immunotherapy of myeloma, once complete responses have been effected by intensive cytotoxic therapy, now possible in up to 50% of newly diagnosed patients.

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.

B lymphocyte function in multiple myeloma: analysis of T cell- and monocyte-dependent antibody production

T-cell and B-cell functions were studied in 35 patients with untreated multiple myeloma (MM) and in 16 patients with MM treated with prednisolone, melphalan and vincristine. The numbers of CD4+ T cells were normal in untreated MM patients, but markedly decreased in treated patients, whereas CD8+ cell numbers were normal in untreated and treated patients. Mitogen-induced as well as antigen-induced lymphocyte proliferative responses were reduced, but not further affected by treatment. The antigen-induced proliferative responses by lymphocytes of treated, but not of untreated patients, correlated positively to the proportions of CD4+ cells among MNC. Taken together, the findings suggest selective loss of CD4+ subpopulations during cytotoxic treatment. Pokeweed mitogen (PWM)-induced Ig production was generally low, but significantly reduced Ig production was only seen in experiments employing MM B cells and monocytes co-cultured with irradiated T-enriched cells. Irradiated MM T cells displayed normal helper function when co-cultured with normal B cells stimulated with PWM. MM B cells and monocytes cultured with irradiated normal T cells produced little Ig; however, MM monocytes were not suppressive. In 2 of 3 patients with either IgG-kappa or IgA-kappa myeloma, the numbers of PWM-stimulated B cells that produced kappa chains were somewhat higher than those found among normal MNC. The impaired ability of antibody production by B cells from untreated MM patients seems to relate to intrinsic B cell defect(s) rather than to abnormal regulation by T cells or monocytes. However, disturbances in the functions of CD4+ cells may be observed in treated MM.

Abnormalities in lymphocyte profile and specificity repertoire of patients with Waldenstrom's macroglobulinemia, multiple myeloma, and IgM monoclonal gammopathy of undetermined significance

The characteristics of T and B lymphocyte profile and B lymphocyte specificity repertoire were compared in patients with Waldenstrom's macroglobulinemia (WM), IgM monoclonal gammopathy of undetermined significance (IgM MGUS), multiple myeloma (MM), and age-matched normal subjects. Patients with MM had both significantly reduced frequency and number of sIg+ (surface Ig) B cells, whereas patients with WM and IgM MGUS had a reduced frequency but normal numbers of sIg+ B cells in circulation as detected in a capping assay. WM was distinguished by the large numbers of cells in the peripheral blood lymphocyte (PBL) pool that expressed CD9 (BA-2) and CD24 (BA-1) and were monoclonal, based on light chain analysis using flow cytometry. The profile of T lineage cells showed that the ratio of CD4:CD8 was significantly reduced in both MM and WM due to a reduction in the CD4 set. The CD4+ cells were qualitatively abnormal as well, with an enriched proportion of the 4B4+ (CDw29) subset and decreased proportion of the Lp220+ (CD45R) subset. This appeared to be an effect of the disease process on the relatively immature Lp220+ set. From clonal analysis, those patients with WM or IgM MGUS (unlike MM patients) did not exhibit enhanced reactivity with auto-Ig determinants, and most WM patients (7/8) and half of the IgM MGUS patients (3/6) did not have enriched proportions of B cells reactive to tetanus toxoid (TT). The TT-specific B cells in both WM and IgM MGUS, in contrast to MM, appeared fully functional in secretion of anti-TT IgM in vivo. We speculate that the more severe immunodeficiency in MM may be controlled or exacerbated by the presence of an anti-Ig network. The absence of this network in WM allows a relatively more effective immune response, but the immunodeficiency that is observed in these patients involves some abnormality in normal lymphocyte differentiation (is also present in MM).

Antigen stimulated IgM secretion by circulating B lymphocytes in patients with benign and malignant IgG gammopathy. Relationship to stage of disease

In the present investigation antigen-driven (sheep red blood cells, SRBC) IgM antibody secretion by B lymphocytes of 22 MM (IgG kappa) patients and 15 patients with IgG kappa monoclonal gammopathy of undetermined significance (MGUS) was studied and compared to that of 20 age-matched healthy controls and five patients with Waldenstrum (IgM) macroglobulinemia (WM). Antibody production by cultured lymphocytes of MM and WM patients was significantly decreased, whereas in MGUS patients it fell within normal limits. We could divide MM patients into three subsets: those who secrete normal amounts of IgM in vitro (patients with the stable type); a second subset of patients whose B lymphocytes secreted low amounts of IgM (MM patients in remission); and a third subset of patients who manifested an intrinsic block of B cell differentiation into IgM-secreting cells (patients with the progressive stage). Sephadex G-10 adherent suppressor cells had no effect on antibody production in the stable and progressive types of disease, whereas in the remission stage they markedly inhibited IgM secretion. Measurement of antigen-driven IgM antibody secretion might help in the differentiation of MGUS and stable (smouldering) MM from frank (progressive) MM at diagnosis. It may also provide a tool for monitoring progression of disease and response to therapy.

T-cells of multiple myeloma patients triggered by the autologous mixed lymphocyte reaction suppress polyclonal immunoglobulin synthesis

To elucidate the possible role of T-cells of patients with multiple myeloma (MM) in the suppression of polyclonal immunoglobulin synthesis. T-cells with and without prior activation by the autologous mixed lymphocyte reaction (AMLR) were added to normal immunoglobulin (Ig)-secreting cultures. The suppression induced by AMLR-activated T-cells from patients with MM was compared to that induced by AMLR-activated T-cells from apparently normal controls. The addition of 10% unstimulated autologous T-cells from patients with MM resulted in minimal suppression of IgG synthesis (87 +/- 19% of baseline values for patients and 115 +/- 21% for controls, no significant difference). The suppression sharply increased when T-cells were preactivated by AMLR and then added in the same concentration to the IgG-secreting cultures (38 + 12% of baseline values for patients compared to 106 + 14% for controls, P less than 0.05). AMLR cultures were performed in the presence of adherent monocytes and after their depletion. The T-cell suppressor effect on normal IgG synthesis was unchanged after monocyte depletion. T-cells preactivated in the AMLR from patients with MM sharply suppress in vitro polyclonal IgG synthesis, and the activation of these suppressor T-cells is not dependent on the presence of monocytes.

Defective generation of alloreactive cytotoxic T lymphocytes (CTL) in human monoclonal gammopathies

The generation of cytotoxic T lymphocytes (CTL) towards allogeneic cells was investigated in 19 patients with monoclonal gammopathy of undetermined significance (MGUS) and 31 patients with multiple myeloma (MM). This function was significantly decreased in all patients. The cytotoxic deficiency was more pronounced in MM with poor prognosis than MM with good prognosis and MGUS patients. A phenotypic analysis of PBT lymphocytes showed that poor prognosis MM also had the highest proportions of activated cells (HLA-DR+) in CD8+ subpopulations. CTL were generated after depletion of CD11+ lymphocytes (including suppressor cells) or after inhibition of suppressor function with deoxyguanosine. No increase of cytotoxicity was detected under these conditions. Exogenous supplementation of recombinant interleukin 2 (rIL-2) was also ineffective. These data indicate that MG PBT lymphocytes are unable to fully differentiate into CTL following allogeneic stimulation. This deficiency is most evident in MM patients already showing the poorest prognosis and the most altered T cell phenotype.

Delay and not deficiency in cap formation of peripheral blood B cells in patients with multiple myeloma

A major problem in the study of peripheral blood (PB) B cells from patients with multiple myeloma (MM) is the distinction between the cells really able to synthesize membrane (m) immunoglobulins (Ig) and those able only to absorb serum Ig passively, since the lymphocytes of such patients are bathed in very high concentrations of monoclonal Ig. In order to reappraise PB B cells (including putative pre-B cells) in MM, we have used three different criteria: (a) the capacity of PB B cells to cap mIg when triggered by an anti-Ig; (b) the presence of B-cell differentiation antigens (CD19, CD20, CD21, and CD37) as specific B-cell markers; and (c) the expression of cytoplasmic mu heavy chain as a marker of pre-B cells. We have found that, in active myeloma (N = 13), the percentages and absolute numbers of PB B cells able to cap mIg (4.25%; 45.43 cells/mm3) were significantly lower than those in healthy donors (8.4%; 151.2 cells/mm3) and those in stable MM (7.67%; 134.39 cells/mm3). In addition, the capping formation in patients with stable or active MM was significantly delayed compared to that in healthy donors. For all the normal individuals and patients investigated, there has been found an excellent correlation between the percentages and absolute numbers of PB B cells able to cap their mIg and those of PB mononuclear cells bearing the four B cell-specific differentiation antigens: CD19, CD20, CD21, and CD37. Finally, virtually no pre-B cells bearing cytoplasmic mu chains have been identified in the peripheral blood from healthy donors and patients with MM.

Humoral immune deficiency in multiple myeloma patients due to compromised B-cell function

Patients with multiple myeloma are generally immunodeficient, with pronounced depression in primary antibody responses. We have attempted to delineate the reasons for the humoral immunodeficiency by analyzing the specificity repertoire of the surface immunoglobulin (Ig)-positive B cells in patients with multiple myeloma or monoclonal gammopathy of undetermined significance (MGUS), in comparison with normal donors. B lymphocytes from 26 patients with multiple myeloma, 12 patients with MGUS, and 8 normal donors were transformed with Epstein-Barr virus (EBV) and cultured at limiting dilution for clonal analysis. The Ig secreted by each clone was analyzed for class and anti-tetanus toxoid (TT) specificity to determine the frequencies of IgM, IgG, anti-TT IgM, and anti-TT IgG antibody-secreting clones. Our objective was to establish whether the inability to mount humoral responses to common environmental pathogens was due to a lack of specific B cells or to inhibition of B-cell function. Our results indicate that the quantitative B-cell deficiency in patients was due to a nonrandom loss of selected sets of B cells. Although most patients had a reduced aggregate number of B cells, the number of TT-specific B cells was normal. There was, on average, a threefold increase in the proportion of the B-cell specificity repertoire devoted to recognition of TT. Forty-four percent of the patients with MGUS were also affected. In addition, the TT-specific B cells in multiple myeloma patients were severely compromised in their ability to secrete antibody or to differentiate to antibody-secreting cells in vivo. This arrest in differentiation appears to be extrinsic to the B cells, as they were fully able to secrete anti-TT antibody after transformation and culture in vitro. We postulate the existence of an autoimmune inhibitory network mediating the arrest in B-cell differentiation and the humoral immune deficiency.

Specificity repertoire of lymphocytes from multiple myeloma patients. I. High frequency of B cells specific for idiotypic and F(ab')2-region determinants on immunoglobulin

The specificity repertoire of B lymphocytes from 14 multiple myeloma patients has been studied using the technique of Epstein-Barr virus (EBV) transformation of peripheral blood lymphocytes (PBL) coupled with clonal analysis by limiting dilution. We find that up to 100% of the B cells from myeloma patients undergoing EBV transformation secrete IgM specific for determinants on the F(ab')2 region of autologous and/or heterologous monoclonal immunoglobulin. In normal individuals 0.02-0.73% of the transformed B cells secrete IgM specific for F(ab')2 determinants. Two patients with monoclonal gammopathy of undetermined significance had only a weak reactivity to F(ab')2 fragments. The number of anti-F(ab')2 B cells was up to 145-fold greater in patients than in normal donors. The majority of antibodies from patient clones recognized determinants shared among 3-12 different F(ab')2 fragments, whereas those originating from normal donor B cells saw determinants expressed on only one or two of the panel of test F(ab')2 fragments. There was a preference for autologous M components and a high proportion of antiidiotypic reactivity in five of eight patients so analyzed. We speculate that these findings indicate the existence of an anti-F(ab')2 immunoregulatory network mediating patient immunodeficiency network mediating patient immunodeficiency, thereby creating an abnormality that may enable the progression of multiple myeloma.