Markers of multiple hematopoietic-cell lineages in multiple myeloma

Multiple myeloma: new evidence and insights from the immunoglobulin heavy chain gene and phenotypes

DNA analysis of the Ig genes has been utilized to delineate the stages of differentiation of normal and malignant B-lineage cells, since the mechanisms involved in V(D)J recombination, somatic hypermutations, and class switch are developmentally regulated. Somatic mutations which result in amino acid substitutions are observed frequently in the Ig variable region genes in multiple myeloma (MM), but there is no intraclonal variation. This fact suggests that the target cell of malignant transformation in MM is a B-lineage cell which already has undergone antigenic selection. This B-lineage cell probably corresponds to a pre-plasma cell or a plasma cell rather than a memory B cell. Tumour cells which share an identical third-complementarity-determining-region (CDR3) sequence with the myeloma cells can be detected from the various fractions representing different stages of B-cell differentiation, such as CD34+, CD20+CD10+, CD20+CD21+, CD20+CD19- cells from the peripheral blood. Thus, the tumour cells in MM are composed of immunophenotypically heterogeneous subpopulations at various stages of differentiation, similar to normal B-lineage cells. These results imply that there is an analogous developmental pathway between the normal B-lineage cells and the tumour cells of MM. Dedifferentiation to the stem cell level may be essential to the malignant transformation in MM.

A solitary plasmacytoma of donor origin arising 14 years after kidney allotransplantation

Allotransplantation of solid organs transfers passenger leucocytes which may give rise to a state of persistent microchimaerism. In this report we describe the case of a patient who developed a solitary plasmacytoma in a transplanted kidney more than 10 years after allografting. The diagnosis was established on the basis of the presence of a monoclonal IgG kappa peak in the serum, and light chain proteinuria, the plasmacytoid features of tumour cells including cell surface expression of IgG, kappa light chains, CD20, CD38 and CD56, the absence of lytic bone lesions and a normal bone marrow biopsy, and the disappearance of the monoclonal IgG peak after graft nephrectomy. A donor origin of the tumour was established by HLA DNA typing of tumour, tumour-free kidney tissue, and peripheral blood leucocytes, respectively.

The clonogenic precursor cell in multiple myeloma

Multiple myeloma is characterized by the monoclonal expansion of plasma cells in the bone marrow. Although the predominant cell type is the plasma cell, the initial oncogenic transformation is considered to take place in a more immature B cell. There is still much controversy about this precursor cell type. Phenotypic analysis of bone marrow and peripheral blood revealed that in multiple myeloma a great diversity exists in the phenotype of the cells considered to be involved. Because of the lack of a myeloma specific genetic lesion it is very difficult to trace back the cell in which the transforming event, leading to multiple myeloma, took place. The only real clonal marker is the idiotype of the immunoglobulin molecule expressed by the myeloma cells. With recombinant DNA technology it is now possible to produce clonal markers for each individual myeloma patient which recognize only the immunoglobulin genes expressed by the myeloma cell and its precursors. The sequences of these myeloma immunoglobulin genes do reveal a lot of information about the stage in the B-cell differentiation pathway in which the oncogenic event might have taken place. The presence of somatic mutations in a non-random fashion without intraclonal variation leads to the conclusion that the precursor myeloma cell could not possibly be a pre-B cell or stem cell but has to be a mature B cell that has been in contact with antigen and has past through the phase of somatic mutation, like a memory B cell or plasmablast.(ABSTRACT TRUNCATED AT 250 WORDS)

CD19 and immunophenotype of bone marrow plasma cells in monoclonal gammopathy of undetermined significance

AIMS

To determine whether a particular phenotype or antigen is preferentially related to monoclonal gammopathies of undetermined significance (MGUS).

METHODS

Bone marrow specimens from 56 patients with MGUS were stained immunocytochemically (ABC peroxidase) for CD38, CD56, CD9, CD10, CD19, CD20, CD22, and MB2. Specimens from patients recently diagnosed with multiple myeloma and reactive bone marrow samples were studied in parallel.

RESULTS

CD38 was expressed on all plasma cells from all MGUS samples tested, while 36% were positive for CD56, CD9 and MB2 were both expressed strongly; CD20 was moderately expressed, and staining for CD10 and CD22 was uncommon. For these five B cell antigens there was no clear difference between their expression in MGUS and in multiple myeloma. A great difference was found for CD19: in MGUS this antigen was expressed on 2-91% of plasma cells (mean 35%) and 77% patients had > 10% positive plasma cells; in multiple myeloma its expression was low and only 12% patients had > 10% positive plasma cells. When these results were converted to numbers of CD19 positive plasma cells per 100 nucleated bone marrow cells, reactive bone marrow and MGUS specimens had a similar number of positive plasma cells. There was no correlation between expression of any of the antigens tested.

CONCLUSIONS

Many of the so-called pre-B, B or activation antigens are present on plasma cells from MGUS specimens, and expression of CD9, CD10, CD20, CD22, MB2, and CD38 in MGUS was very similar to that in multiple myeloma. CD56 was frequently expressed in MGUS. In this series CD19 was highly expressed in MGUS but not in multiple myeloma. Plasma cells bearing this antigen could represent the non-neoplastic process and determination of its expression could be useful for the diagnosis of MGUS.

Multiple myeloma clones are derived from a cell late in B lymphoid development

We have previously demonstrated that the immunoglobulin (Ig) heavy chain variable region (VH) sequences expressed by the malignant clone in multiple myeloma (MM) contain a high degree of somatic mutation without clonal diversity. This sequence can be used to identify all members of the malignant clone in this B cell malignancy. We sequenced the variable regions expressed by patients with MM and generated primers from the complementarity determining region (CDR) sequences specific for each patient's tumor. Using these primers, we performed PCR amplification on highly purified subpopulations of cells separated by expression of CD10, CD34 and CD38. The results of these experiments demonstrate: 1) there is a small fraction of CD10-expressing tumor cells in MM patients, 2) CD34-bearing malignant cells do not exist in MM, and 3) although the vast amount of tumor is in the CD38-expressing cells, a small amount of tumor is in the CD38-negative population. We also used these primers to determine whether pre-class switch (i.e., Cmu-expressing lymphocytes) clonal cells exist in these patients. After PCR amplification with CDR1 and Cmu primers, colony hybridization was performed using both framework 3 (FR3) and CDR3 probes. Out of > 200 FR3-hybridizing colonies, < or = 5 colonies also hybridized with the CDR3 probe. Colonies which hybridized with both these probes were sequenced, and none of these sequences matched even closely the CDR3 expressed by the malignant clone. These results make the existence of a pre-class switch malignant cell unlikely in MM. Overall, these results suggest that the malignant clone in MM derives from a cell late in B lymphocyte development.

Immunoglobulin gene sequence analysis to further assess B-cell origin of multiple myeloma

To further characterize the B-cell origin of multiple myeloma, our laboratory performed immunoglobulin gene sequence analyses of four cases of myeloma (three immunoglobulin A and one immunoglobulin G). Three tumors expressed VH3 genes and one expressed a VH1 gene, while the light chains included two V lambda and one V kappa III; one light chain was not isolated. The closest homology to published germ line genes ranged from 91 to 97%. In two cases, the expressed VH genes were compared with the putative germ line precursor VH genes isolated from autologous granulocyte DNA and appeared to have mutated randomly from the germ line gene. By sequencing multiple clonal isolates from each tumor sample, we found no evidence for ongoing mutation in three cases; in one case, however, clonotypic heterogeneity was evident. The analysis of DH- and JH-region genes revealed (i) limited or absent N nucleotide insertions (two of four cases), (ii) the presence of a DH-JH junction resulting from sequence overlap between the DH and JH genes (one of four cases), (iii) the absence of somatic mutations (two of four cases), and (iv) restricted JH gene usage of a JH6 polymorphism (three of four cases). These analyses of DH and JH genes suggest that multiple myeloma, similar to what has been proposed for chronic lymphocytic leukemia, may derive from B cells which have rearranged during fetal development rather than during adult life.

Mouse anti-human interleukin-6 receptor monoclonal antibody inhibits proliferation of fresh human myeloma cells in vitro

Interleukin-6 (IL-6) is a major growth factor in multiple myeloma. We investigated the effect of mouse anti-human IL-6 receptor monoclonal antibody (anti-IL-6R mAb) on the in vitro proliferation of freshly isolated myeloma cells from 21 patients to evaluate the therapeutic potential. The addition of anti-IL-6R mAb inhibited more than 30% of the spontaneous proliferation of myeloma cells in 9 of 21 cases in a dose- (0.1 to 20 micrograms/ml) and time-dependent manner. The inhibitory effects of anti-IL-6R mAb did not differ significantly from that of anti-IL-6 mAb, and were correlated with the extent of the response of myeloma cells to IL-6. Flow cytometric analysis showed that all myeloma cells expressed IL-6R, whose intensity was not correlated with either the extent of response of myeloma cells to IL-6 or the inhibitory effects of anti-IL-6R mAb on proliferation of myeloma cells. Although our study showed heterogeneity in the proliferative responses of myeloma cells to IL-6 and anti-IL-6R mAb, these observations suggest the possibility of using anti-IL-6R mAbs for treating some patients with multiple myeloma whose growth depends on IL-6.

N- and K-ras oncogenes in plasma cell dyscrasias

N- and K-ras oncogene mutations represent the most frequent molecular lesions in plasma cell dyscrasias. They are not randomly distributed since they are detectable in multiple myeloma (MM) (9-31%) and plasma cell leukemia (PCL) (30%), and not in monoclonal gammopathy of undetermined significance (MGUS) and solitary plasmacytoma (SP). Codons 12, 13 and 61 of N- and K-ras genes have been found mutated. Mutations affecting codon 61 of N-ras gene are the most frequent finding. A heterogeneous pattern of mutations is described with a prevalence of purine-pyrimidine transversions. Ras gene mutations have been predominantly detected in myelomas characterized by an advanced stage disease, and adverse prognostic parameters. These findings suggest that ras mutations represent a late molecular lesion and may be implicated in tumor progression rather than tumor initiation.

Cellular origin and extent of clonal involvement in multiple myeloma: genetic and phenotypic studies

The cellular origin and extent of clonal involvement in multiple myeloma (MM) are controversial. The third-complementarity-determining region (CDR3) of the immunoglobulin heavy chain gene is the target region of VH replacements and somatic mutations. We analysed the CDR3 sequences of myeloma cells from eight newly diagnosed and three relapsed patients in order to elucidate the target cell of malignant transformation in MM. We also examined the extent of clonal involvement in MM using a CDR3 clone-specific nucleic acid probe. The peripheral lymphocytes from the five MM patients were separated into fractions such as CD34+, CD20+CD10+, CD20+CD21+, CD20+CD19- and CD2+ cells. Amplified CDR3 DNAs from these subpopulations were hybridized with the probe specific to each patient's tumour cells. We found no evidence of ongoing VH replacements or somatic mutations in CDR3 in MM. However, frequent nucleotide mutations in D and JH segments were observed. Circulating malignant cells were detected in the CD34+ and all of the CD20+ subpopulations, but not in the CD2+ fraction. MM is a neoplasm originating from a B-lineage cell which has already undergone antigen-dependent selection. Nevertheless, the tumour cells are composed of heterogeneous subpopulations at various stages of differentiation, similar to normal B-lineage cells. Conversely, T cells were not involved in MM. These results imply that there is an analogous developmental pathway between the normal B-lineage cells and the tumour cells of MM.

Cell surface markers in multiple myeloma

OBJECTIVE

To describe the immunophenotype of normal and myelomatous plasma cells (PCs) and the changes in immunoregulatory nonmyelomatous cells in multiple myeloma (MM).

DESIGN

The cell surface markers (antigens) associated with this common cancer were reviewed.

MATERIAL AND METHODS

Immunophenotypic characterization of both normal PCs and their counterpart malignant hematopoietic cells can be achieved by using monoclonal antibodies and either flow cytometry or immunocytochemical techniques.

RESULTS

Normal PCs are heterogeneous and express, in addition to cytoplasmic immunoglobulins, the antigens CD9, CD10, CD13, CD19, CD20, CD33, CD38, and D-related human leukocyte antigen (HLA-DR). This heterogeneity also occurs in malignant PCs. Myelomatous PCs may express, in addition to CD38 (the most typical PC marker), the antigens CD9, CD10, HLA-DR, and CD20. Other non-B-cell lineage markers such as myeloid (CD13, CD14, CD15, CD33, CD41, and glycophorin A), T-cell (CD2 and CD4), and natural killer-associated (CD56) antigens, as well as CD23, CD24, CD25, CD37, CD39, CDw40, CD45R, CD71, and certain unclustered antigens (R1-3, PCA-1, PCA-2, PC1, 62B1, 8A, 8F6, and MM4), have been noted in myelomatous PCs. The presence of these antigens in the myeloma cells may have a prognostic value--for example, the expression of CD20 and of myelomonocytic antigens (CD11b, CD13, CD14, CD15, and CD33) may be related to a poor prognosis. The adverse prognostic implication of the expression of CD10 initially described in MM has not been subsequently confirmed. Patients with MM may have mononuclear cells in their peripheral blood that express the same antigens as those expressed by the myeloma cells in their bone marrow. The presence of such cells or their therapy-associated decrease or disappearance may be related to the prognosis of patients with MM.

CONCLUSION

The presence of cell surface markers on PCs and their prognostic significance in patients with MM warrant further investigation.

Familial aggregation of haematological neoplasms: a controlled study

Advances in molecular biology techniques suggest that many haematological neoplasms originate from a transformation process at the level of the haemopoietic pluripotential stem cell. While familial aggregation has been reported for many haematological neoplasms, most studies were uncontrolled and examined the presence of the same haematological neoplasm as the index case. We assessed the familial aggregation of all haematological neoplasms in 4061 family members of 189 patients with various haematological neoplasms and two control groups: 955 relatives of 36 patients with non-malignant haematological disorders and 508 relatives of 33 patients with type II diabetes mellitus. Data collection included self-administered questionnaires. The odds ratio for haematological neoplasms among relatives of the index cases adjusted for age, sex, ethnicity, number of relatives in the family, and degree of familial linkage in the study group versus the two control groups was 3.62 (95% confidence interval, 1.44-9.07; P < 0.01). The vast majority of the haematological neoplasms among family members did not belong to the same histopathological category as the index cases. The data support the hypothesis of a genetic predisposition to haematological neoplasms. The fact that the aggregation is not disease specific is consistent with a defect in the pluripotent haemopoietic stem cell.

CD34 selection for purging in multiple myeloma and analysis of CD34+ B cell precursors

Selection of CD34+ hematopoietic progenitor cells from autografts may be performed in multiple myeloma (MM) to minimize contamination with tumor cells. This approach is based on the assumption that the malignant cells do not express the CD34 antigen. Therefore, we first compared the CD34+/CD10+ and CD34+/CD19+ subpopulations from bone marrow (BM) and peripheral blood (PB) of fourteen MM patients and five normal controls. No difference between the respective early B cell subsets of both groups could be observed. Using tricolor flow cytometry, the CD19 expression on CD34+/CD10+ cells in BM was found to increase continuously from CD19- to CD19dim. In contrast, circulating CD34+/CD10+ cells did not coexpress the CD19 antigen. This population may contain myeloid progenitor cells or bipotential progenitor cells of the myeloid and lymphoid lineage as suggested by data obtained with fetal liver cells. Further functional studies are required. Enrichment of CD34+ cells with immunomagnetic beads was performed from BM of three MM patients and four normal donors. The CD34+ cells were selected with the HPCA-1 antibody and detached from the beads with chymopapain. Compared with the starting cell preparation, a 3.97 +/- 0.48 log (mean +/- SE) reduction of plasma cells could be achieved after CD34 selection. On morphological examination, 84% +/- 4% of the cells in the CD34+ fraction (MM) were immature blasts. The plating efficiency for hematopoietic colony forming cells was 9.7% +/- 2.8% in the CD34 selected fraction of the MM group, reflecting a 51-fold increase as compared with the starting population.(ABSTRACT TRUNCATED AT 250 WORDS)

Relapse of aggressive myeloma after complete remission in secondary acute leukemia: coincidence or consequence?

We describe a patient with multiple myeloma who developed secondary acute myelomonocytic leukemia after long-term melphalan treatment. Following two courses of low-dose cytarabine, complete remission of the A.M.L. was achieved. Shortly thereafter an aggressive relapse of the quiescent myeloma occurred with acute renal failure and massive infiltration of bone marrow with multinucleated giant plasma cells. Although it is well known that administration of melphalan to patients with multiple myeloma increases the likelihood of A.M.L., this case demonstrates that treatment of A.M.L. in a patient with multiple myeloma may perhaps influence the course of multiple myeloma.

Multiple myeloma: 'early' plasma cell phenotype identifies patients with aggressive biological and clinical characteristics

The immunological phenotype of bone marrow myeloma cells and peripheral blood lymphocytes was evaluated in 38 untreated myeloma patients. A striking increase of monotypic cells expressing the same light chain as the M component was observed in bone marrow from 18/38 (47%) patients. A two-colour analysis clarified that the majority of myeloma cells co-expressed plasma cell and B lymphocyte markers (cyIg, CD38, CD56 and sIg), and were regarded as early-plasma cells (early-PC). In the remaining patients, myeloma cells expressed plasma cell markers only (late-PC). Phenotype corresponded to a distinct morphological pattern: early-PC showed a lympho-plasmocytoid feature with significantly lower diameters than late-PC (12.1 v 14.8 microns, P < 0.007). Moreover, the plasma cell labelling index was significantly increased in early-PC patients (1.2 v 0.5%, P < 0.04). In peripheral blood from patients with early-PC, monotypic cells co-expressing sIg and CD38, CD56, but not CD19, were also detected. These data suggest a recirculation of early-PC. Myeloma cells maintained their phenotypic pattern during the course of the disease. This observation suggests that the degree of maturation is an intrinsic characteristic of the myeloma cell population in individual patients. The evaluation of prognostic factors, such as beta 2-microglobulin, C-reactive protein and neopterin, showed a statistically significant increase in the early-PC patients, suggesting a poor outcome. In conclusion, myeloma cell phenotype allows identification of a myeloma variant with aggressive biological and clinical characteristics.

Coincidental polycythemia vera and multiple myeloma: case report and review

Polycythemia vera (PCV) and multiple myeloma are both clonal disorders of hematopoietic stem cells. The simultaneous occurrence of these diseases in an individual patient is rare. A case of synchronous PCV and smoldering myeloma is presented and the literature is reviewed. The issues of clinical importance in this unusual case include the mechanisms of anemia in multiple myeloma, the difficulty in using anemia as a parameter on which to base the initiation of therapy for myeloma, and the risks of treatment-induced leukemia and myelodysplasia.

Evidence for a bone marrow B cell transcribing malignant plasma cell VDJ joined to C mu sequence in immunoglobulin (IgG)- and IgA-secreting multiple myelomas

Multiple myeloma is a B cell malignancy characterized by the expansion of plasma cells producing monoclonal immunoglobulins (Ig). It has been regarded as a tumor arising at the B, pre-B lymphocyte, or even stem cell level. Precursor cells are presumed to proliferate and differentiate giving rise to the plasma cell clonal expansion. Antigenic features and specific Ig gene rearrangement shared by B lymphocytes and myeloma cells have supported this hypothesis. However, the existence of such a precursor is based upon indirect evidence and is still an open question. During differentiation, B cells rearrange variable (V) regions of Ig heavy chain genes, providing a specific marker of clonality. Using an anchor polymerase chain reaction assay, these rearranged regions from five patients with multiple myeloma were cloned and sequenced. The switch of the Ig constant (C) region was used to define the B cell differentiation stage: V regions are linked to C mu genes in pre-B and B lymphocytes (pre-switch B cells), but to C gamma or C alpha in post-switch B lymphocytes and plasma cells (post-switch B cells). Analysis of bone marrow cells at diagnosis revealed the presence of pre-switch B cells bearing plasma cell V regions still joined to the C mu gene. These cells were not identified in peripheral blood, where tumor post-switch B cells were detected. These pre-switch B cells may be regarded as potential myeloma cell precursors.

The bone marrow of multiple myeloma patients contains B cell populations at different stages of differentiation that are clonally related to the malignant plasma cell

One of the distinguishing features of multiple myeloma (MM) is the proliferation of a clonal plasma cell population in the bone marrow (BM). It is of particular interest that the tumor plasma cells appear to be restricted to the microenvironment of the BM and are rarely detected in the peripheral system, yet the disease is found widely disseminated throughout the axial skeleton. Furthermore, isolation of MM tumor cell lines has proven to be quite problematic due to their slow growth rate. These observations have instigated the search for earlier cells in the B cell lineage that are clonally related to the plasma cell tumor and that may represent the growth fraction of the tumor. We used allele-specific oligonucleotides (ASO) derived from the third complementarity determining region of the rearranged tumor immunoglobulin heavy chain gene to detect isotypes clonally related to the plasma cell tumor. By reverse transcribing RNA from the BM with a panel of CH primers (mu, delta, alpha, and gamma), followed by ASO-polymerase chain reaction amplification, we demonstrate the existence of preswitch isotype species that are clonally related to the myeloma tumor. Furthermore, we show that separation of the BM cells into CD45+ and CD38+ cell populations results in a lineage-specific expression of the clonally related RNA molecules, with the C mu and C delta in the CD45+, and C gamma in the CD38+ population. Interestingly, clonally related C alpha transcripts are also derived from the CD45+ fraction. These results confirm the presence of B cell populations clonally related to the plasma cell tumor and are consistent with models that propose the existence of myeloma precursors.

Expression of GpIb on plasma cells in a patient with monoclonal IgG and acquired von Willebrand disease

To get insights into the pathogenesis of acquired von Willebrand disease associated with plasma cell dyscrasias, we searched for the expression of the physiological von Willebrand factor receptor, the GpIb/GpIX complex, on bone marrow plasma cells. The monoclonal spike in our patient corresponded to IgG kappa molecules; there was no plasma inhibitor to vWF:Ag or vWF:RiCoF. The bone marrow contained 1-2% plasma cells. Fresh bone marrow cells or plasma cells enriched bone marrow cells after a 48 h in vitro culture in the presence of interleukin 6 were stained by an immuno alkaline phosphatase technique using monoclonal antibodies (mAb) to von Willebrand factor, GpIb alpha and beta chain, GpIIb/IIIa and Gp IX. Two different mAb to GpIb alpha chains reacted with the majority (75%) of plasma cells whereas all other reagents yielded no staining. Malignant plasma cells from patients with multiple myeloma without haemostatic disorder were unreactive with anti-GpIb mAb. These data suggest that in some patients with acquired von Willebrand syndrome there is a GpIb mediated selective adsorption of von Willebrand factor on clonal plasma cells.

Plasma cell myeloma in the horse. A case report and literature review

Plasma cell myelomas in horses have been reported infrequently. Data from 10 cases, 9 from the literature and 1 new case, are used to characterize the disease in the horse. Hot-blooded horses (7/10), specifically Quarter Horses (4/10), were most often affected. Median age at diagnosis was 11 years (range, 3 mo-22 yr) and both male (5) and female horses (5) were represented equally. Clinical findings included weight loss (6/8), anorexia (4/8), fever (4/8), limb edema (4/8), pneumonia (3/8), rear leg paresis/ataxia (3/8), epistaxis (3/8), palpable lymphadenopathy (2/8), and bone pain (2/8). Anemia (8/8) was present routinely, and in three horses, RBCs were macrocytic. Leukopenia (2/8), thrombocytopenia (2/8), and circulating plasma cells (3/8) were variable findings. Except for abnormal protein concentrations and hyponatremia (3), abnormal results from serum biochemical analysis including hypocholesterolemia (1), hypercalcemia (1), and azotemia (1) were reported infrequently. Hyperproteinemia (8/9), hypoalbuminemia (7/9), and hyperglobulinemia (8/9) were characteristic but not invariable findings. Monoclonal proteins (7/7) were detected in the alpha 2, beta, or gamma region by serum electrophoresis. The paraprotein's heavy chain, determined in four horses, was a subclass of IgG. Three horses had decreased concentrations of normal immunoglobulins. Variable proteinuria (trace to 4+) was detected by routine urinalysis in four of six horses. Bence Jones proteinuria was detected in one of five horses (heat precipitation) and monoclonal proteins were detected in two of three electrophoresed urine samples. Three of the horses had lytic bone lesions detected radiographically. Bone marrow aspirates were diagnostic in two of five horses.(ABSTRACT TRUNCATED AT 250 WORDS)

The involvement of adhesion molecules in the biology of multiple myeloma

Multiple myeloma represents a B cell malignancy characterized by a monoclonal proliferation of plasma cells. A striking feature of the disease is the tendency of the malignant plasma cells to affect mainly the bone marrow environment and to invade the peripheral blood only in the terminal stage. The growth of myeloma plasma cells is believed to be regulated by a functional interplay between the tumor cells and the bone marrow stroma, involving the action of various cytokines. This growth control is most probably mediated by close cellular contact of the myeloma cells and marrow stromal components. Therefore it can be assumed that myeloma plasma cells possess the ability to interact with the bone marrow stroma. Until now the adhesive mechanisms that may underlie this interaction, remain undetermined. We investigated the expression of several adhesion molecules on bone marrow plasma cells in myeloma patients and normal controls. Normal as well as malignant plasma cells were found to be strongly positive for the intercellular adhesion molecule ICAM-1, the fibronectin receptor VLA-4 and the lymphocyte homing receptor CD44. In addition, a much weaker expression of the second fibronectin receptor VLA-5, the laminin receptor VLA-6 and the vitronectin receptor CD51 was demonstrated. In contrast to normal plasma cells, myeloma cells can also express the neural cell adhesion molecule N-CAM. In this report we discuss the possible role of adhesion molecules in the pathogenesis and clinical evolution of multiple myeloma.

Restricted expression of immunoglobulin light chain mRNA and of the adhesion molecule CD11b on circulating monoclonal B lineage cells in peripheral blood of myeloma patients

Circulating monoclonal B cells in peripheral blood from patients with multiple myeloma or with monoclonal gammopathy of undetermined significance (MGUS) have previously been shown to express CD19, CD20, and PCA-1 and are predominantly CD45R0+, characterizing them as very late stage B cells. This work shows that the abnormal B cells are monoclonal as defined by their exclusive expression of either kappa or lambda light chain mRNA, and that the same type of light chain mRNA is expressed in both bone marrow plasma cells and blood B cells. These abnormal tumour-related circulating B cells express high densities of CD11b, a beta 2-integrin, which is expressed in a conformationally active state as defined by reactivity with monoclonal antibody 7E3. Normal peripheral blood B cells which do not bear CD11b acquire a high density after stimulation with pokeweed mitogen (PWM). At day 4 of culture, the expression of CD11b on normal CD19+ B cells was nearly comparable to that of the circulating myeloma late stage B cells. After PWM stimulation of circulating myeloma B cells the expression of CD11b was gradually lost during 4 days of culture, suggesting that its expression is dynamically regulated. Two patients with no phenotypically abnormal B cells in their blood at diagnosis acquired a large subset of CD11b+ B cells 4 weeks after initiation of chemotherapy. In most patients, a subset of the circulating myeloma B cells express a low density of CD5. The proportion of CD19+ B cells in the bone marrow expressing CD11b was much reduced compared with peripheral blood B cells, and CD11b was not detectable on plasma cells in the bone marrow, suggesting a sequential relationship of the B-cell subsets detected in our population of patients, involving gradual loss of CD11b concurrent with the loss of CD19 during B lineage differentiation. These cells appear to represent a continuously differentiating monoclonal B lineage culminating in the CD11b- plasma cell entrenched in the bone marrow. We speculate that the expression of conformationally active CD11b on the abnormal B cells in peripheral blood mononuclear cells of myeloma patients facilitates transendothelial migration of circulating myeloma B cells to the bone marrow.

Multiple myeloma and chronic lymphocytic leukemia: parallels and contrasts

Multiple myeloma (MM) and chronic lymphocytic leukemia (CLL) are closely related B-cell cancers. Parallel and divergent features of these diseases are reviewed. In MM, expression of multiple hemopoietic lineage-associated antigens on the malignant cells and the substantial likelihood of progression to acute myelogenous leukemia suggest transformation of a pluripotent stem cell. In CLL, transformation more likely involves a committed B-cell progenitor. Another difference is that clonal evolution with associated cytogenetic progression is common in MM but not CLL. Other data, including studies of proto-oncogenes and tumor suppressor genes, suggest that MM results both from increased proliferation and accumulation of tumor cells, whereas tumor cell accumulation is the predominant feature of CLL. These differences may be reflected in the seemingly greater role of cytokine abnormalities in MM progression. For example, osteoclast-activating properties of some cytokines account for bone involvement in MM but not in CLL. MM and CLL share common features such as stage-dependent anemia and immune deficiency. Both diseases respond to alkylating agents but vary markedly in their sensitivity to fludarabine (CLL greater than MM) and glucocorticoids (MM greater than CLL). Differences between these diseases in progression-free interval and survival may reflect different definitions of premalignant and malignant phases rather than biologic differences. Detailed comparisons between MM and CLL may provide additional insights into these and related B-cell cancers.

Immunogenetics of cell surface antigens of human cancer

Hybridoma technology, immunohistochemistry and molecular genetic techniques have paved the way for a general serological mapping of molecules expressed on the surface of normal and neoplastic cells. The emerging findings challenge cell lineage-based models of differentiation and point to new, modular concepts to explain complex tumor phenotypes. In parallel studies, the repertoire of T-cell recognized tumor antigens--still mysterious but probably quite distinct from the antibody-defined repertoire--has also become accessible to molecular analysis.

Early disappearance of murine plasmocytoma stem cells in long-term bone marrow culture

Long-term bone marrow culture (LTBMC) was evaluated as a purging procedure in the murine plasmocytoma MOPC-315s system. MOPC-315s cells injected in Balb-c mice rapidly proliferate both in marrow and spleen, where macroscopic tumor colonies develop. A linear relationship between the number of injected cells and spleen colonies was observed, consistent with the presence of 1 clonogenic myeloma stem cell out of 1800 cells. In vitro, MOPC-315s cells are easily identifiable as rosette-forming cells (RFC+) with trinitrophenil acid (TNP) coated sheep red blood cells. When bone marrow (BM) cells containing 20-40% RFC+ were seeded in LTBMC, RFC+ rapidly decreased and were no longer detectable by day 14 of culture. Clonal Ig gene rearrangement was evident at time 0, but it was no more detectable later on. In addition, cells taken at days 14 and 21 of culture were no more tumorigenic when injected in vivo. The results suggest the efficacy of the LTBMC for the in vitro elimination of myeloma cells, including the neoplastic stem cells.

[Prognostic factors and monitoring of myeloma]

An improved knowledge of the initial prognostic factors of multiple myeloma and regular monitoring of the disease should result in the choice of the most effective treatment. The conventional prognostic factors have been divided into three stages by Durie and Salmon. These stages are based on the proportion and type of the monoclonal component, on haemoglobin, calcium and creatinine blood levels and on the extent of bone lesions. However, this widely used classification has certain disadvantages: the size of the tumoral mass is evaluated mainly from the proportion of monoclonal gammopathy, the bone lesions are difficult to determine and the kinetics of cell proliferation are not taken into account. Parameters with high prognostic value have recently been demonstrated; they include beta 2-microglobulin, LDH, interleukin-6, C-reactive protein, serum albumin and kinetic of cell proliferation. When associated, these data allow to establish prognostic staying that are at least as relevant as those of the Durie-Salmon's classification. Monitoring of patients with multiple myeloma by means of a time-related curve of either the tumoral mass or the amount of monoclonal gammopathy leads to the best possible treatment.

Langerhans-cell histiocytosis in an adult patient with multiple myeloma

A 44-year-old man who had suffered for 6 years from multiple myeloma developed multiple papules on the face and chest. Histological examination of these papules revealed the infiltration of predominantly histiocytic cells into the dermis and into parts of the epidermis. These cells were seen on electron-microscopic study to have Langerhans granules in the cytoplasm, which led to a diagnosis of Langerhans-cell histiocytosis concomitant with multiple myeloma. Possible explanations for this unusual association are discussed.

Current concepts on monoclonal gammopathies

This is a review of the monoclonal gammopathies, including a discussion of cause. The role of T lymphocytes and B lymphocytes is presented. The recognition of a monoclonal protein in the serum and urine is presented in detail. The frequency of benign and malignant monoclonal gammopathies is provided. A long-term follow-up of 241 patients with apparently benign monoclonal gammopathy is examined closely. In this series, multiple myeloma, macroglobulinaemia, amyloidosis, or related disorders developed in 22% of the 241 patients with long-term disease. The median duration from the recognition of the monoclonal protein until the development of serious disease was approximately eight to ten years. The differentiation of benign from malignant monoclonal gammopathies is examined in detail. The point is made that patients must be followed indefinitely because malignancy may develop more than 20 years later. The association of monoclonal gammopathies with other apparently unrelated diseases is discussed.

Molecular analysis of clonality in plasma cell dyscrasias

It has been suggested that multiple myeloma, generally considered a neoplastic disorder of mature plasma cells, may arise from a pluripotent haemopoietic stem cell. The possibility that circulating lymphocytes derive from the same neoplastic progenitor has been tested in a large number of studies in the past few years, as proof of the interest that this subject is raising among scientists, and also of its elusiveness. We studied a group of 29 patients with plasma cell dyscrasias in order to evaluate clonality of haemopoietic cell populations. The X-linked markers hypoxantine phosphoribosyltransferase (HPRT) and phosphoglycerate kinase (PGK) disclosed no monoclonal component in seven heterozygous women. Analysis of immunoglobulin gene rearrangement with four probes showed a germline configuration in samples from 25/29 patients. Only four bone marrow samples from subjects with aggressive disease had rearranged C mu sequence; one had rearrangement of JH and C mu.

Immunocytochemical investigation of normal and chronic lymphocytic leukaemia lymphocytes reveals unexpectedly frequent reactivity with some myelomonocytic associated antibodies

Information about the expression of some myelomonocytic markers in lymphocytes of patients with B-CLL is scarce. We studied the CD13, CD14, CD11c and CD68 surface antigens in 42 controls and in 38 patients with B-CLL to detect their possible reactivity. Eighty-nine percent of B-CLL expressed very strongly the CD14 antigen; on the contrary, the other myelomonocytic antigens tested were very weakly expressed. Forty-one of 42 controls showed a few CD14-positive lymphocytes with a statistical difference between normal and CLL lymphocytes. No statistical difference was recorded either between CD14 expression and Rai's staging system or Binet's stages, nor between CD14 and bone marrow involvement and doubling time or between CD14 and heavy or light chain expression. A minor B lymphocytic subset in humans coexpresses the CD14 and CD5 antigens, it being increasingly speculated that B chronic lymphocyte leukaemias originate precisely from this B CD5- and CD14-positive cells. Just as the CD5 antigen is regarded as an excellent B-CLL marker, it seems to us that a strong expression of the CD14 antigen might have the same diagnostic relevance.

Multiparameter analyses of normal and malignant human plasma cells: CD38++, CD56+, CD54+, cIg+ is the common phenotype of myeloma cells

Plasma cells obtained from bone marrow samples of 45 patients with MM, eight patients with MGUS, eight patients with Waldenström's macroglobulinaemia (WM), one patient with immunocytoma, and 12 controls were characterized by immunophenotyping, estimation of DNA content, and labeling index, as well as by morphological analysis. Plasma cells from 37/45 myeloma and 5/8 MGUS patients expressed CD38 and CD56 (N-CAM) on their surface but were negative for other NK cell-associated antigens such as CD16 (Fc gamma RIII) or CD2. All tumor cells of less-differentiated cell type (WM, immunocytoma) and normal polyclonal plasma cells were negative for CD56. CD56-specific mRNA was demonstrated in myeloma cells by northern blot analysis. Another adhesion molecule, ICAM-1 (CD54), was found on plasma cells from all patients and controls examined. Coexpression of CD19 (1/45), CD20 (9/45), or CD33 (3/45) was rare and CD10 with CD14 was expressed by a small tumor cell subpopulation of only one myeloma patient. The individual pattern of surface marker expression was not associated with a special-type myeloma protein isotype, stage or status of disease, LI or histological classification; however, a correlation between CD56 expression or histological classification and DNA content of the tumor cells was found.

Frequent expression of haemopoietic and non-haemopoietic antigens by neoplastic plasma cells: an immunohistochemical study using formalin-fixed, paraffin-embedded tissue

There is increasing evidence that neoplastic plasma cells express various haemopoietic and non-haemopoietic antigens. Since this issue could raise problems in diagnostic histopathology, we have investigated 51 cases of multiple myeloma (plasmacytoma) systematically with a broad panel of antibodies applicable on paraffin-embedded and mildly decalcified tissue. In approximately 90% of the cases the neoplastic plasma cells reacted with at least one antibody detecting haemopoietic antigens: MB2 (75%), DF-T1/CD 43 (59%), UCHL1/CD 45RO (47%), Ki-B3 (41%), anti-LCA/CD 45 (40%), L26/CD 20 (26%), 4KB5/CD 45RA (18%), Ber H2/CD 30 (10%), anti-neutrophil elastase (4%), anti-Leu-7/CD 57 (8%), Dako-M1/CD 15 (2%), KP1/CD 68 (2%) and anti-glycoprotein IIIa (2%). In approximately 70% of the cases the cells reacted with antibodies against non-haemopoietic antigens: anti-epithelial membrane antigen (65%), BMA120 (53%), anti-vimentin (44%), anti-pan-cytokeratin/KL1 (8%), anti-carcino-embryonic antigen (6%) and HMB45 (6%). Lack of awareness of the frequent expression of both haemopoietic and non-haemopoietic antigens by neoplastic plasma cells could lead to mis-diagnosis of plasmacytomas as malignant lymphomas or even as carcinomas or sarcomas.

Immunoglobulin gene rearrangement in multiple myeloma: limitations of Southern blot analysis

Thirty-six patients with early and advanced multiple myeloma were investigated with Southern blot analysis to determine the presence of immunoglobulin gene rearrangement as evidence of clonality. Rearrangements were not uniformly found, being detected in only 14 of 19 patients with newly diagnosed myeloma and in 15 of 17 cases of clinically advanced myeloma. A correlation between percentage of bone marrow plasma cells and detection of immunoglobulin gene rearrangement was noted; however, in four cases of early myeloma with > 10% marrow plasma cells, no rearrangement was found. These results suggest that Southern blot analysis may not be an optimal method for the determination of clonality in plasma cell dyscrasias or, alternatively, that a proportion of the plasma cells found on bone marrow examination in some patients with early myeloma may not be monoclonal.

Simultaneous occurrence of myelomonocytic leukemia and multiple myeloma: involvement of common leukemic progenitors and their developmental abnormality of "lineage infidelity"

We investigated the origin of leukemic progenitors in a case of the simultaneous occurrence of myelomonocytic leukemia and multiple myeloma (IgG-kappa). At presentation, myeloperoxidase and nonspecific esterase-positive myelomonocytic cells had proliferated up to 12.2 x 10(9)/liter in the peripheral blood. Bone marrow cell differentials revealed the coexistence of myelomonocytic cells (30%) and atypical plasmacytoid cells (26%). Myelomonocytic cells in peripheral blood expressed both myeloid antigens (CD11b, CD13, CD14, CD15, CD33) and T/B-lymphoid antigens (CD2, CD4, CD5, CD7, CD10, PCA-1). Bone marrow mononuclear cells (BMMC) could be divided into PCA-1 strongly positive and PCA-1 weakly positive populations, which were considered to represent myeloma cells and myelomonocytic cells, respectively; the former were CD2-positive (CD2+), CD14-, and CD15-, whereas the latter were CD2+, CD14+, and CD15+. Immunohistochemical analysis revealed that, in addition to plasmacytoid cells, a minority of myelomonocytic cells showed a positive reaction for IgG staining, and production of IgG was observed in the culture supernatant of CD14+ myelomonocytic cells in peripheral blood. Southern blot analysis revealed the presence of two identical rearrangement bands of immunoglobulin heavy chain gene in both BMMC containing myeloma cells and myelomonocytic cells and CD14+ myelomonocytic cells in peripheral blood. In a long-term methylcellulose assay, peripheral blood mononuclear cells produced large compact colonies consisting of macrophages and IgG+ plasmacytoid cells (M phi/P colonies), while BMMC produced a different type of colonies consisting of CD14+ myelomonoblasts, macrophages, and IgG+ plasma cells (Mb/M phi/P colonies) in addition to M phi/P colonies. Recloning experiments showed that primary Mb/M phi/P colonies gave rise to both secondary M phi/P and Mb/M phi/P colonies. These observations strongly suggest that common leukemic progenitors provide both myeloma and myelomonocytic leukemia cells, and the mechanism of "lineage infidelity" is probably involved in the development of their "bilineal" differentiation.

Expression of the neural cell adhesion molecule (CD56) by human myeloma cells

Recent studies in multiple myeloma indicate that molecules associated with different haematopoietic lineages may be expressed aberrantly by myeloma cells. In order to investigate this phenomenon further, we studied the immunophenotype of bone marrow cells from 21 patients with multiple myeloma using a panel of monoclonal antibodies against T,B, myelomonocytic, and natural killer (NK)-cell antigens. Leu-19/NKH1 (CD56), a molecule identical to N-CAM, which is normally expressed by neuroectodermal and NK cells, was found in 13 patients (62%). Dual-parameter flow cytometry was used to correlate N-CAM positivity with DNA aneuploidy or cytoplasmic immunoglobulin expression as markers of myeloma cells. When N-CAM was found positive, other haematopoietic antigens were expressed only in three out of 13 cases (23%). In contrast, myeloma cells not expressing N-CAM frequently exhibited pre-B cell markers, myeloid antigen, and HLA-DR, respectively (seven out of eight cases, 88%). Six out of eight N-CAM-negative myelomas were of the IgG lambda isotype, otherwise no clearcut association with basic clinical and laboratory parameters was noted. We conclude that N-CAM expression is a common finding in multiple myeloma. Whether its expression and the observed antigenic heterogeneity is just a manifestation of malignancy or N-CAM may play a role in the biology of multiple myeloma regarding tumour cell spread, remains to be explained.

Immunophenotypic heterogeneity of multiple myeloma: influence on the biology and clinical course of the disease. Castellano-Leones (Spain) Cooperative Group for the Study of Monoclonal Gammopathies

In 112 untreated myeloma patients we have analysed the immunophenotype of plasma cells both by immunofluorescence (IF) and immunocytochemistry (APAAP). Both techniques yielded similar results pointing to an important degree of heterogeneity in antigenic expression not only between different patients but also within the same patient. The expression of CD38 and Han-PC1 antigens (Ags) was almost constant (greater than 90% positive cases), while CD9 was detected in 66% of the cases. On the other hand, less than one third of patients were positive for CD10, CD20 and HLA-DR and generally with a weak expression (less than 30% positive plasma cells). In occasional cases plasma cells were weakly positive for the myelomonocytic markers CD13 (9%), CD15 (25%) and CD14 (6%). The possibility that this heterogeneity might be the result of different stages of differentiation of the neoplastic clone is suggested both by the positive correlation in the expression of some of these antigens (CD10, CD9, CD20, HLA-DR) and by the relationship between CD10 and myeloid antigens with immature plasma cell morphology. Finally, the cALLA antigen does not seem to be of significant value in predicting survival. Moreover, none of the other markers explored showed a clear influence in the course of the disease, although the tendency towards a lower survival found for the CD20+ cases as well as the association of the expression of some antigens and advanced clinical stage, may warrant further studies in a larger series of patients.

Expression of myelomonocytic antigens is associated with unfavourable clinicoprognostic factors in B-cell chronic lymphocytic leukaemia

The cross-lineage expression of five myelomonocytic antigens (CD11b, CD11c, CD13, CD14, and CD15) was analysed in neoplastic lymphocytes from 100 consecutive B-cell chronic lymphocytic leukaemia (B-CLL) patients. CD14 antigen was detected on lymphocytes from more than 50% of patients whilst smaller percentages of samples were positive for CD11b (21%), CD11c (26%), CD13 (22%), and CD15 (7%). The presence of the CD13 antigen on neoplastic lymphocytes showed a statistically significant association with the two most important unfavourable clinicoprognostic factors in B-CLL: advanced clinical stage (CD13, P less than 0.01 by the Rai staging system; P less than 0.05 by the Binet staging system) and the diffuse pattern of bone marrow infiltration (CD13, P less than 0.001). A multiple logistic regression analysis showed that the increased risk for CD13-positive patients (13.7-fold higher than CD13-negative cases; P = 0.001) of presenting a diffuse pattern of bone marrow infiltration is independent of all other prognostic factors analysed including sex, age, lymphocyte counts, and clinical stage. A statistically significant association of CD11c (P = 0.002) and CD11b (P = 0.032) expression with the pattern of bone marrow infiltration was also found. Our results indicate for the first time a statistically significant association of CD13, CD11c, and CD11b antigens with unfavourable prognostic factors in B-CLL. They suggest that the cross-lineage expression of myeloid-associated surface peptidase (CD13-aminopeptidase N) and/or cell adhesion molecules (CD11c-LeuCAMc, CD11b-LeuCAMb) may influence the biological and clinical behaviour of chronic lymphoproliferative disorders of B cells.