No abstract

A monoclonal antibody (MoAb) that defines a novel terminal B-cell- restricted antigen, termed HM1.24, was developed against a human plasma cell line. The MoAb, designated anti-HM1.24, reacted with five different human myeloma cell lines, as well as with monoclonal neoplastic plasma cells obtained from the bone marrow or peripheral blood of patients with multiple myeloma or Waldenstrom's macroglobulinemia. The HM1.24 antigen was also expressed by mature Ig- secreting B cells (plasma cells and lymphoplasmacytoid cells) but not by other cells contained in the peripheral blood, bone marrow, liver, spleen, kidney, or heart of normal individuals or patients with non- plasma-cell-related malignancies. The anti-HM1.24 MoAb bound to human myeloma RPMI 8226 cells with an affinity constant of 9.2 x 10(8) M-1, indicating approximately 84,000 sites/cell. By immunoprecipitation assay under reducing conditions, this MoAb identified a membrane glycoprotein that had a molecular weight of 29 to 33 kD. Our studies indicate that the HM1.24-related protein represents a specific marker of late-stage B-cell maturation and potentially serves as a target antigen for the immunotherapy of multiple myeloma and related plasma cell dyscrasias.

Multiple myeloma (MM) cells cause devastating bone destruction by activating osteoclasts in the bone marrow milieu. However, the mechanism of enhanced bone resorption in patients with myeloma is poorly understood. In the present study, we investigated a role of C-C chemokines, macrophage inflammatory protein (MIP)–1α and MIP-1β, in MM cell-induced osteolysis. These chemokines were produced and secreted by a majority of MM cell lines as well as primary MM cells from patients. Secretion of MIP-1α and MIP-1β correlated well with the ability of myeloma cells to enhance osteoclastic bone resorption both in vitro and in vivo as well as in MM patients. In osteoclastogenic cultures of rabbit bone cells, cocultures with myeloma cells as well as addition of myeloma cell-conditioned media enhanced both formation of osteoclastlike cells and resorption pits to an extent comparable to the effect of recombinant MIP-1α and MIP-1β. Importantly, these effects were mostly reversed by neutralizing antibodies against MIP-1α and MIP-1β, or their cognate receptor, CCR5, suggesting critical roles of these chemokines. We also demonstrated that stromal cells express CCR5 and that recombinant MIP-1α and MIP-1β induce expression of receptor activator of nuclear factor-κB (RANK) ligand by stromal cells, thereby stimulating osteoclast differentiation of preosteoclastic cells. These results suggest that MIP-1α and MIP-1β may be major osteoclast-activating factors produced by MM cells.

Abstract.We immunohistochemically investigated the localization of activin A and follistatin in various human tissues with specific antibodies to recombinant human (rh-) activin A and rh-follistatin.

Multiple myeloma (MM) cells cause devastating bone destruction by activating osteoclasts in the bone marrow milieu. However, the mechanism of enhanced bone resorption in patients with myeloma is poorly understood. In the present study, we investigated a role of C-C chemokines, macrophage inflammatory protein (MIP)–1α and MIP-1β, in MM cell-induced osteolysis. These chemokines were produced and secreted by a majority of MM cell lines as well as primary MM cells from patients. Secretion of MIP-1α and MIP-1β correlated well with the ability of myeloma cells to enhance osteoclastic bone resorption both in vitro and in vivo as well as in MM patients. In osteoclastogenic cultures of rabbit bone cells, cocultures with myeloma cells as well as addition of myeloma cell-conditioned media enhanced both formation of osteoclastlike cells and resorption pits to an extent comparable to the effect of recombinant MIP-1α and MIP-1β. Importantly, these effects were mostly reversed by neutralizing antibodies against MIP-1α and MIP-1β, or their cognate receptor, CCR5, suggesting critical roles of these chemokines. We also demonstrated that stromal cells express CCR5 and that recombinant MIP-1α and MIP-1β induce expression of receptor activator of nuclear factor-κB (RANK) ligand by stromal cells, thereby stimulating osteoclast differentiation of preosteoclastic cells. These results suggest that MIP-1α and MIP-1β may be major osteoclast-activating factors produced by MM cells.

Free light chains (FLC) are a natural product of B lymphocytes and, as such, represent a quantifiable biomarker of cellular proliferation. Accurate measurement of the concentrations of these components in serum and urine provides a unique means of ascertaining B cell immunoglobulin synthesis during physiologic and, especially, pathologic states, where such information has important diagnostic and therapeutic implications. Previously, use of such quantitative assays has been limited due to the lack of potent serologic reagents specific for these components. We have immunized mice with kappa- and lambda-type monoclonal human light chains (Bence Jones proteins (BJP)) and have obtained monoclonal antibodies (MoAbs) that differentiate between unbound and bound light chains. These highly specific MoAbs were used to measure by ELISA the concentrations of FLC in the serum of 22 normal individuals and in urine from 16 of these subjects. The mean serum kappa and lambda FLC concentrations were found to be 16.6+/-6.1 microg/ml and 33.8+/-14.8 microg/ml, respectively. In contrast, the values for urinary kappa and lambda FLC were 2.96+/-1.84 microg/ml and 1.07+/-0.69 microg/ml, respectively. In each case studied, the serum kappa:lambda ratio was consistently less than that of urine (mean values, serum approximately 1:2; urine approximately 3:1). That the rate of synthesis of lambda-type FLC exceeded that of kappa was evidenced in assays of culture fluid supernatants of unstimulated normal peripheral blood mononuclear cells (PBMC), where the mean kappa:lambda ratio was determined to be 1:1.4. Metabolic studies in which mice were injected with pools of kappa- and lambda-type BJP prepared in ratios of 1:1, 1:2 and 1:4 demonstrated that, regardless of the proportion, kappa FLC were preferentially excreted. Our studies provide the first evidence that lambda FLC are secreted by normal PBMC at a greater rate than are kappa FLC, as evidenced in biosynthetic studies and by measurement of their serum concentrations. Further, we posit that quaternary structural differences between the two light-chain isotypes may account for the predominance of kappa versus lambda components in urine.

No abstract

The urine-based ELISA (URINELISA H. pylori Antibody) is very accurate and should be useful as an alternative to serum-based ELISAs for screening of H. pylori infection.