The early postnatal development of salivary antibody and immunoglobulin response in children orally colonized with a nonpathogenic, probiotic strain of E. coli.

The development of levels of secretory immunoglobulins (SIgs) in newborns' saliva was examined under physiological conditions and after artificial colonization with nonpathogenic, probiotic bacterial strain E. coli O83. Higher levels of secretory immunoglobulin M (SIgM) and secretory immunoglobulin A (SIgA) were detected in the saliva of breast-fed children when compared with those of bottle-fed infants. SIgM was found earlier than SIgA, the levels of both SIgM and SIgA decreased after weaning. Breastfeeding actively stimulates local immunity on mucosal membranes of newborn infants. Early mucosal colonization with nonpathogenic E. coli bacteria stimulates the mucosal immune system to produce specific antibodies as well as nonspecific secretory immunoglobulins.

Multiple myeloma and related disorders. Lessons from an animal model.

This short review of our own work presents two aspects of the studies on multiple myeloma (MM) in an animal model--the aging C57BL/KaLwRij mouse: 1. the immunological/biological aspect of the development of monoclonal B-cell proliferative disorders, the so-called monoclonal gammopathies (MG), and 2. the use of the mouse myeloma of the 5TMM lines for studies on the etiology/pathogenesis of MM and for developing new ways of treatment of this disease. Our research revealed that there are at least four major mechanisms in the development of MG. Many of the results were confirmed in clinical studies and lead to a new classification of MG according to their biology and possible pathogenesis. Most of MG can be classified into one of the following categories: 1. B-cell malignancies, 2. B-cell benign neoplasia, 3. MG due to an immunodeficiency with T/B cell imbalance, and 4. Antigen driven MG.

Ibandronate reduces osteolytic lesions but not tumor burden in a murine model of myeloma bone disease.

We determined the effects of the potent bisphosphonate ibandronate in a murine model of human myeloma bone disease. In this model, bone lesions typical of the human disease develop in mice following inoculation of myeloma cells via the tail vein. Treatment with ibandronate (4 micrograms per mouse per day) significantly reduced the occurrence of osteolytic bone lesions in myeloma-bearing mice. However, ibandronate did not prevent the mice from developing hindlimb paralysis and did not produce a detectable effect on survival. There was no significant effect of ibandronate on total myeloma cell burden, as assessed by morphometric measurements of myeloma cells in the bone marrow, liver, and spleen, or by measurement of serum IgG2b levels. These results support clinical findings that bisphosphonates may be useful for the treatment of myeloma-associated bone destruction, but suggest that other therapies are also required to reduce tumor growth.

DNA vaccines against haematological malignancies.

DNA vaccines against cancer have to activate an inadequate or damaged immune system in order to attack residual cancer cells. Although the potential problem of tolerance may be overcome by transplantation, provision of high levels of T-cell help is likely to be an important factor in stimulating effective immune pathways. The fusion gene approach appears to provide the required help, and offers a rational design for raising both antibody and T-cell mediated attack against lymphoma and myeloma, which express idiotypic antigen at the cell surface or as a secreted protein respectively. Intriguingly, preliminary data indicate that the fusion gene approach promotes antibody responses against a different cell surface tumour antigen, CEA. Strategies for using DNA vaccines to induce attack on processed peptides bound to MHC class I molecules are also being developed. We hope and anticipate that all categories of tumour antigen may be susceptible to this powerful new technology. The critical clinical requirement, however, will be to treat the presenting tumour with maintenance or restoration of immune capacity. We await results of the preliminary clinical trials with great interest.

DNA vaccines with single-chain Fv fused to fragment C of tetanus toxin induce protective immunity against lymphoma and myeloma.

Vaccination with idiotypic protein protects against B-cell lymphoma, mainly through anti-idiotypic antibody. For use in patients, DNA vaccines containing single-chain Fv derived from tumor provide a convenient alternative vaccine delivery system. However, single-chain Fv sequence alone induces low anti-idiotypic response and poor protection against lymphoma. Fusion of the gene encoding fragment C of tetanus toxin to single-chain Fv substantially promotes the anti-idiotypic response and induces strong protection against B-cell lymphoma. The same fusion design also induces protective immunity against a surface Ig-negative myeloma. These findings indicate that fusion to a pathogen sequence allows a tumor antigen to engage diverse immune mechanisms that suppress growth. This fusion design has the added advantage of overcoming potential tolerance to tumor that may exist in patients.

Immunoglobulin VH gene sequence analysis of spontaneous murine immunoglobulin-secreting B-cell tumours with clinical features of human disease.

The 5T series of multiple myelomas (MM) and Waldenstrsöm's macroglobulinaemia-like lymphomas (WM), which developed spontaneously in ageing mice of the C57BL/KaLwRij strain, shows clinical and biological features that closely resemble their corresponding human diseases. In order to compare the patterns of somatic mutation in VH genes of mouse tumours with those of human counterparts, we have determined and analysed sequences of immunoglobulin VH genes in five cases of murine MM, two of WM and one of biclonal benign monoclonal gammopathy (BMG). Four of five MM and 2/2 WM cases used VH genes of the large J558 family; one MM used a gene of the VGAM3.8 family, and both clones of the BMG used genes of the 36-60 family. N-region insertions were observed in all cases, but D-segment genes were only identified in 6/9 cases, which were all from the D-SP family and translated in reading frame 3. Compared with human MM, in which the VH genes have been found to be consistently hypermutated (mean% +/- SD = 8.8 +/- 3.2), the degree of somatic mutation in the murine tumours was significantly lower (mean% +/- SD = 2.9 +/- 2.3). There was no significant evidence of clustering of replacement mutations in complementarity determining regions (CDR), a feature considered to be characteristic of antigen-selected sequences. However, one clone of the biclonal BMG case showed intraclonal variation, a feature described in some cases of human BMG. These results indicate that murine VH genes in mature tumours differ from human counterparts in the level and distribution of somatic mutations, but support the concept that BMG may be distinct from MM.

Monoclonal gammopathies in aging mu, kappa-transgenic mice: involvement of the B-1 cell lineage.

Monoclonal gammopathies (MG) are monoclonal proliferative disorders of B cells at the differentiation stage of Ig production. They can be detected in the serum, either as transient or as persistent homogenous immunoglobulin (H-Ig) components. The exact phenotype, localization, and cell lineage origin of the precursor cells of MG are unknown, but may be crucial for both the correct diagnosis and for timely efficient treatment of the malignant forms. We used for the first time transgenic (Tg) mice (Sp6; mu/kappa) to study the origin of MG. In the mu, kappa Tg mice a small proportion of B cells can still produce endogenous IgM. These cells are of B-1 cell origin. The MG in Tg mice showed a later onset and a lower frequency than those in littermate control mice, mainly due to a four times lower frequency of benign monoclonal gammopathy. The 10% of B-1 cells that were able to produce endogenous Ig led to the development of MG in a frequency that was half the number of MG found in normal littermates. None of the MG in Tg mice produced an Ig of the Tg origin and therefore it can be concluded that they originated from B-1 cells.

Galactose-deficient IgA1 in sera of IgA nephropathy patients is present in complexes with IgG.

IgA1 proteins from sera of patients with IgA nephropathy (IgAN) are galactosylated to a lesser degree than those from healthy controls. The increased reactivity of intact or de-sialylated serum IgA1 with N-acetylgalactosamine (GalNAc)-specific lectins, Helix aspersa (HAA) and Caragana arborescens (CAA) and de-sialylated IgA1 with Helix pomatia (HPA) and Bauhinia purpurea (BPA) indicated that the Gal deficiency is in glycans located in the hinge region of IgA1 molecules. De-sialylated IgA from sera of 81 IgAN patients bound biotin-labeled lectin HAA more effectively than did de-sialylated IgA from 56 healthy controls (P < 0.0001). Similar results were observed for 67 IgAN patients and 52 controls with second lectin, CAA (P < 0.001). The binding patterns for 9 patients with mesangial proliferative glomerulonephritis of non-IgA origin were similar to those for controls. Incompletely galactosylated IgA1 capable of binding GalNAc-specific lectins was detected in complexes with IgG as demonstrated by ELISA, size-exclusion chromatography and sucrose gradient ultracentrifugation. The formation of IgA1-IgG complexes may affect the serum level of IgA1 by reducing the rate of its elimination and catabolic degradation by the liver.

Frequency of clonal dominance in the specific antibody response to DNP-HSA in CBA and C57BL mice reflects their susceptibility to age-associated development of monoclonal gammopathies.

The effects of age, genetic background, and neonatal thymectomy on the levels and the heterogeneity of the specific antibody response were investigated in an experimental mouse model. Both intact and neonatally thymectomized (NTx) C57BL/KaLwRij (C57BL) and CBA/BrARij (CBA) mice were immunized at the age of 3 ("young") or 22 months ("old"). Highly sensitive antigen-specific immunoblotting techniques (ABL), in combination with agar-electrophoresis and isoelectric focusing (IEF), were used to investigate total specific antibody levels, the number of responding antigen-specific clonotypes, and the dominance of responding B cell clones in the antibody response against dinitrophenylated human serum albumin. After immunization, the specific antibody levels progressively increased in all experimental groups with the exception of old C57BL mice. All mice responded with a specific polyclonal heterogeneous response. In addition, some mice showed a clonal dominance of antibody-producing cells, as is reflected in the appearance of distinct homogeneous antibody components (H-Ab) in the sera. This clonal dominance was scarce in CBA mice but frequent in C57BL mice. Age at time of immunization and NTx had little if any additive effect on the incidence of H-Ab in either mouse strain. All dominant clones showed different electrophoretic mobility, indicating the proliferation of various clonotypes and not a strain-specific dominance of one clone. In old C57BL mice the specific antibody response was more restricted in heterogeneity, as is illustrated by more visible spectrotype bands in IEF and subsequent ABL. Hence, in old C57BL mice smaller amounts of specific antibodies were produced by fewer clones. Still, the incidence of H-Ab in this group was the same as that in the group of young C57BL mice. This indicates that at old age the responding B cell clones are more prone to becoming clonally dominant in C57BL mice. This tendency correlates with the high incidence of spontaneously developing monoclonal gammopathies in aging C57BL mice.

A murine model of human myeloma bone disease.

Myeloma causes a devastating and unique form of osteolytic bone disease. Although osteoclast activation is responsible for bone destruction, the precise mechanisms by which myeloma cells increase osteoclast activity have not been defined. An animal model of human myeloma bone disease would help in clarification of these mechanisms. Multiple myeloma occurs spontaneously in aging C57 BL/KaLwRij mice and has all of the features of the disease in humans, including the characteristic bone lesions. The disease can be induced in normal C57 BL/KaLwRij mice by inoculation of fresh marrow-derived cells from mice with myeloma, but this model is difficult to study because of variability in the number of myeloma cells in marrow-derived preparations. To develop a better animal model of human myeloma bone disease, we have established and subcloned a cell line from this murine myeloma and found that it causes osteolytic bone lesions in mice characteristic of human myeloma bone disease. The cell line produces interleukin-6, but grows independent of exogenous interleukin-6. Mice inoculated intravenously with the cultured cells predictably develop an identical disease to the mice injected intravenously with fresh bone-marrow-derived myeloma cells, including monoclonal gammopathy and radiologic bone lesions. We found that some of the mice became hypercalcemic, and the bone lesions are characterized by increased osteoclast activity. We found identical results when we inoculated Nu/Bg/XID mice with cultured murine myeloma cells. Because we can inoculate mice with precise numbers of cells and predict accurately when the mice will develop bone lesions, become hypercalcemic, and die, this should be a convenient model for determining the mechanisms by which the myeloma cells cause osteoclast activation in this model of human myeloma bone disease.

Vectorial transcytosis of dimeric IgA by the Calu-3 human lung epithelial cell line: upregulation by IFN-gamma.

We have developed an in vitro airway epithelial cell model for dimeric immunoglobulin (Ig) A (dIgA) transcytosis that allows the assessment of polymeric Ig receptor (pIgR) gene expression and actual dIgA transport. Tight monolayers of human lung-derived Calu-3 adenocarcinoma cells grown on permeable membranes expressed pIgR mRNA and released more secretory component (SC; P < 0.01) and secretory IgA (sIgA; P < 0.02) into the apical medium than into the basolateral medium. Transcytosis of dIgA was not due to paracellular leakage and was inhibited to approximately 20 and 30% of control values by anti-pIgR antibodies and the competitive ligand pentameric IgM, respectively. Interferon-gamma (IFN-gamma; 200 U/ml) induced pIgR mRNA expression and increased apical release of free SC and sIgA in a dose-dependent fashion (P < 0.0001). Basolateral addition of increasing amounts of dIgA dose dependently increased apical sIgA release (P < 0.0001). These data indicate that Calu-3 monolayers are capable of translocating dIgA through the pIgR. In addition, we show the integrated stimulatory effect of IFN-gamma on pIgR mRNA and protein expression and dIgA transcytosis.

Structural differences among serum IgA proteins of chimpanzee, rhesus monkey and rat origin.

Asparagine-linked sugar chains were quantitatively released from chimpanzee, Rhesus monkey and rat IgA proteins as oligosaccharides by hydrazinolysis, converted to radioactive oligosaccharides by reduction with NaB3H4, and separated into neutral and two acidic fractions by paper electrophoresis. The acidic oligosaccharides were converted to neutral ones by sialidase digestion, indicating that they are sialyl derivatives. However, the content of N-acetyl and N-glycolyl neuraminic acids was different among three species. The neutral and sialidase-treated acidic oligosaccharides were fractionated by Bio-Gel P-4 column chromatography in combination with linkage-specific sequential exoglycosidase digestion. Although IgA molecules from these species have mainly biantennary complex-type sugar chains, the contents of fucose and bisecting N-acetylglucosamine residues displayed marked species differences. In addition to these sugar chains, a small amount of the high mannose-type sugar chains was detected in chimpanzee and rat, but not in Rhesus monkey IgA. These results indicated that the processing of asparagine-linked sugar chains of IgA is different in each species.

Organ involvement and phenotypic adhesion profile of 5T2 and 5T33 myeloma cells in the C57BL/KaLwRij mouse.

The aim of this study was to evaluate the tissue infiltration and phenotypic adhesion profile of 5T2 multiple myeloma (MM) and 5T33 MM cells and to correlate it with that observed in human disease. For each line, 30 mice were intravenously inoculated with myeloma cells and at a clear-cut demonstrable serum paraprotein concentration; mice were sacrificed and a number of organs removed. The haematoxylin-eosin stainings on paraffin sections were complemented with immunohistochemistry using monoclonal antibodies developed against the specific MM idiotype. When analysed over time, 5T2 MM cells could be observed in bone marrow samples from week 9 after transfer of the cells. For the 5T33 MM, a simultaneous infiltration was observed in bone marrow, spleen and liver 2 weeks after inoculation. Osteolytic lesions consistently developed in the 5T2 MM, but this was not consistent for 5T33 MM. PCNA staining showed a higher proliferative index for the 5T33 MM cells. The expression of adhesion molecules was analysed by immunohistochemistry on cytosmears: both 5T2 MM and 5T33 MM cells were LFA-1, CD44, VLA-4 and VLA-5 positive. We conclude that both lines have a phenotypic adhesion profile analogous to that of human MM cells. As the 5T2 MM cells are less aggressive than the 5T33 MM cells, their organ distribution is more restricted to the bone marrow and osteolytic lesions are consistently present, the former cell line induces myeloma development similar to the human disease.

Follow-up of bone lesions in an experimental multiple myeloma mouse model: description of an in vivo technique using radiography dedicated for mammography.

The evolution of bone lesions in transplantable C57BL/KaLwRjj 5T mouse myeloma (MM) has been followed in vivo. Mice were anaesthetised and a radiograph of the pelvis and hind legs was performed by a radiograph dedicated for mammography. This is the first description of an in vivo technique under experimental conditions whereby the development of bone lesions owing to the MM growth was demonstrated.

Evaluation of monoclonal antibodies with specificity for human IgA, IgA subclasses and allotypes and secretory component. Results of an IUIS/WHO collaborative study.

51 monoclonal antibodies (McAb) with putative specificity for human IgA, the IgA subclasses, Am allotypes or secretory component (SC) were evaluated for immunoreactivity and specificity by nine laboratories employing immunodiffusion, agglutination, immunohistological assays, immunoblotting and direct binding and competitive inhibition enzyme immunoassays. McAbs specific for IgA PAN (n = 24), IgA1 (n = 7), IgA2 (n = 3), IgA2m(2) (n = 2), non-IgA2m(2) (n = 4) and SC or secretory IgA (n = 5) were identified that were immunoreactive and specific in the assays employed. The McAbs identified as IgA- or SC-reactive were shown to be non-reactive to human IgG, IgM, IgD, IgE, kappa and lambda by direct binding and competitive inhibition immunoassays. Interestingly, no McAbs with restricted specificity for IgA2m(1) were identified. Some McAbs displayed higher affinity and/or better performance in one or several of the assay groups. The IgA- and SC-specific McAbs identified in this international collaborative study have potential as immunochemical reference reagents to identify and quantitate monomeric and polymeric IgA in human serum and secretions.

Tenfold increased incidence of spontaneous multiple myeloma in long-term immunosuppressed aging C57BL/KaLwRij mice.

Persons undergoing maintenance immunosuppressive treatment (MIST) were shown to be at increased risk for the development of early malignancies, often of cells of the immune system. Very little is known about the late effects of MIST. Some clinical studies indicated an age-related increase in the incidence of plasma-cell disorders, in particular in that of multiple myeloma (MM). In the present study the influence of MIST on the development of monoclonal B-cell proliferative disorders, monoclonal gammopathies (MG), was studied in an animal model, the C57BL/KaLwRij mouse. This strain is known for its susceptibility to develop with aging MG similar to those in humans. Two widely used treatment protocols (azathioprine/prednisolone and Cyclosporin A/prednisolone) were tested in young and adult mice. Both regiments were shown to increase 10-fold the incidence of spontaneous multiple myeloma. Unexpectedly, the same high incidence of MM and in addition the development of a life-shortening lymphoblastic lymphoma were found in a high frequency in the control group that received Cremophor EL only, i.e., the solvent of Cyclosporin A. Repeated experiments with another lot of Cremophor showed a 6-fold increased frequency of NM but no lymphoblastic lymphoma. With respect to the life-span and the incidence of hemopoietic neoplasms the least harmful drugs for MIST appeared to be azathioprine/prednisolone. The results of the experiments in this C57BL/KaLwRij mouse model give a warning for increased incidence of MM in susceptible aging individuals and address a question whether Cremophor EL is a safe solvent for Cyclosporin A.

Search for the antigen-specificity of homogeneous IgG components (H-IgG) after allogeneic bone marrow transplantation.

After allogeneic BMT, transient homogeneous Ig components (H-Ig) can be detected in the sera of most graft recipients. So far, data on the antigen-specificity and therefore the function of these H-Ig are not available. Such information may be important for our understanding of the underlying mechanisms that are responsible for these excessive clonal B cell expansions, and it may help to delineate the functional antibody repertoire after BMT. In the present study, sera of 98 paediatric BM graft recipients were investigated for the potential presence of H-Ig of IgG isotype (H-IgG) with specificity towards a panel of antigens, including vaccine and herpes virus antigens, auto-antigens and allo-antigens. The vast majority of H-IgG in sera of BM graft recipients were unreactive when tested for this panel of antigens. However, in four cases, antigen-specificity of H-IgG to tetanus toxoid could be demonstrated after vaccination with that antigen. An explanation for the negative findings may be either that a restricted antibody production had been elicited by other non-tested antigens, eg substances of colonizing and translocating bacteria or of food antigens, or that the H-IgG components may have anti-idiotype or anti-'self' specificity.

Cytogenetic findings in mouse multiple myeloma and Waldenström's macroglobulinemia.

Multiple myeloma (MM) and Waldenstrom's macroglobulinemia-like lymphoma (MW) appear spontaneously in C57BL/KaLwRij mice at a frequency of 0.5% and 0.2%, respectively. They can readily be propagated by intravenous transfer of mainly bone marrow or spleen cells into syngeneic recipients. Previous studies demonstrated that these mouse malignant monoclonal gammopathies (MMG) show clinical and biologic features that closely resemble those of the corresponding human diseases and thus could be used as experimental models. We report on cytogenetic analysis of two mouse MW and five MM in vivo cell lines of the 5TMM series propagated in syngeneic mice. These studies demonstrated clonal abnormalities in all cell lines, hyperdiploid karyotype in both MW and one MM lines, and hypotriploidy, hypertriploidy, or hypotetraploidy in the other lines. Structural abnormalities of chromosome 15 were observed in all MM lines. In five MM lines, frequent rearrangements were also found for chromosome numbers 1, 2, 5, and 12. A single chromosomal abnormality, as found in induced mouse plasmacytomas and resembling Burkitt lymphoma, was not found in mouse MM and MW. It was concluded that spontaneously originating C57BL MM of the 5T series is a better model for human MM than pristane-induced BALB/c or NZB plasmacytoma.

The origin of IgG production and homogeneous IgG components after allogeneic bone marrow transplantation.

Pediatric recipients (n = 25) of an allogeneic bone marrow (BM) graft were selected on the basis of informative IgG allotype (Gm) differences between the BM donor and the recipient. To investigate the kinetics of the appearance of IgG of donor origin and the disappearance of IgG of recipient origin, G1m and G2m allotype levels were quantified in sera obtained at regular intervals between 3 months and 5 years after BM transplantation (BMT). For this quantification, a dot immunobinding assay (DIBA) has been developed. In 19 of 22 informative recipients, the Gm allotype distribution had reached the range of values expected on the basis of the Gm phenotype of the donor within 6 months after BMT. Remarkably, IgG of recipient origin persisted in 15 of 18 informative recipients until last follow up, ie, for several years after BMT. In addition to the origin of total IgG production, the origin of homogeneous IgG components (H-IgG) appearing after BMT was investigated. H-IgG of donor origin could be detected as early as 3 weeks after BMT, but also H-IgG of recipient origin were present in 8 of 13 informative recipients for a period of up to 1 year after BMT. We conclude that host-type IgG-producing cells were not eradicated by the (myeloablative) conditioning regimen and persisted in a high number of graft recipients. It is our hypothesis that lack of graft-versus-host disease (GVHD) in the majority of these recipients results in the persistence of IgG-producing cells of host origin. These observations may be relevant for the evaluation of patients who received allogeneic BMT for the treatment of multiple myeloma.