Autoimmunity and the pathogenesis of plasma cell tumor induction in NZB inbred and hybrid mice

Neoplastic development in plasma cells

An increasing number of model systems of plasma cell tumor (PCT) formation have been and are being developed. Discussed here are six models in mice and multiple myeloma (MM) in humans. Each model illustrates a unique set of biological factors. There are two general types of model systems: those that depend upon naturally arising mutagenic changes (pristane-induced PCTs, 5TMM, and MM) and those that are associated with oncogenes (Emu-v-abl), growth factors [interleukin-6 (IL-6)], and anti-apoptotic factors (Bcl-xL/Bcl-2). PCTs develop in several special tissue microenvironments that provide essential cytokines (IL-6) and cell-cell interactions. In mice, the activation and deregulation of c-myc by chromosomal translocations is a major feature in many of the models. This mechanism is much less a factor in MM and the 5T model in mice. Genetically determined susceptibility is involved in many of the mouse models, but only a few genes have been implicated thus far.

Pristane induced gene activation

Studies were performed to examine the effects of 2,6,10,14-tetramethyl pentadecane (pristane) versus 12-O-tetradecanoylphorbol 13-acetate (TPA) on the activation of the CAT gene under the regulatory control of viral promoter/enhancer elements transfected into NIH-3T3, CV-1 and COS-7 cells. The results of these studies demonstrated that (1) pristane or TPA induced trans-activation of SV2cat, HIVcat, RSVcat and MMTVcat in cells transfected with each respective plasmid construct, (2) only pristane induced activation of pA10cat and pOSP/11 and (3) neither TPA nor pristane trans-activated pSV0cat. Furthermore, treatment with either pristane or TPA elicited changes in the morphology of each of the cell lines. Collectively these results indicate that pristane is a potent inducer of gene expression and exhibits similar characteristics as the tumor promoter, TPA.

Pristane induced effects on chromatin of rat lymphoid cells

The effects of pristane on the conformation of chromatin in cells isolated from the lymphoid tissues of pristane-treated Copenhagen rats were examined by flow cytometry, thermal denaturation, sensitivity to enzymatic digestion, and histone protein analyses. Decreases were observed in the fluorescent intensities of propidium iodide (PI) stained nuclei isolated from lymphoid cells of pristane-treated rats when compared with normal rat lymphoid nuclei. Studies to address the possible basis for the pristane-induced changes in the DNA staining characteristics of lymphocytes demonstrated that 1) there were no decreases in the amount of DNA present in the nuclei, 2) nuclei isolated from pristane treated rats were less sensitive to thermal denaturation, as well as DNase I enzymatic digestion, and 3) there were apparent increases in the expression of the H1 histone proteins. Collectively, these results suggest that pristane elicits a conformational change in the chromatin which may be mediated by altered expression of nuclear-associated histone proteins.

Dietary effects of pristane on rat lymphoid tissues

Studies were conducted to assess the normal tissue-associated levels of pristane (2,6,10,14,-tetramethylpentadecane) in Copenhagen rats during ontogeny and adult life and to address whether or not dietary pristane can be adsorbed from the gut and disseminated throughout the body. During the course of this study the possible effects of dietary pristane on chromatin conformation of lymphoid cells were also examined by flow cytometry. The data indicated that 1) pristane crossed the placenta and accumulated in fetal tissues, 2) neonates were exposed to pristane via the colostrum, 3) there were significant increases in the amount of tissue-associated pristane in young adults and subsequent redistribution of the pristane to the muscle and adipose tissues in older rats and 4) after dietary exposure, significantly elevated levels of pristane were associated with the tissues and concomitant changes in chromatin conformation were observed. Collectively, these results suggest that pristane was adsorbed from dietary sources, disseminated to the tissues and exerted a transient, yet marked effect on chromatin of lymphoid cells in rats.

Antinuclear antibodies and nuclear antigens in NZB myeloma ascitic fluids

Approximately 5-10% of ascitic fluids from 411 NZB myeloma tumors were found to possess either antinuclear (ANA) or Coombs antibodies. Some fluids showed anti-SM specificity, which is thought to be unique to systemic lupus erythematosus (SLE). In addition, the ascitic fluids were found to contain large amounts of DNA and Sm autoantigens. Further passage of ANA-positive myelomas indicated that the autoantibodies were not products of the myeloma cells themselves. The sporadic appearance of unsuspected autoantibodies in ascitic fluids may cause confusion when working with myeloma or with hybridoma reagents. Furthermore, the development of SLE-specific anti-Sm antibodies in this context suggests parallels between myeloma development and autoimmunity.

binding constants of levans and D-fructo-oligosaccharides to BALB/c and NZB D-fructan-specific, myeloma proteins, determined by affinity electrophoresis

The association constants for the interaction of BALB/c (UPC 10, Y5476, W3082, and UPC 61) and NZB (PC 3660) myeloma anti-D-fructans in pure form, or in ascitic fluids, with high-molecular-weight levans (Ka) and with such low-molecular-weight compounds as rye-grass levan, inulin, sucrose, and D-fructo-oligosaccharides (Kia) were determined by affinity electrophoresis, measuring the extent of retardation of the D-fructan-specific band by levan and its restoration by the low-molecular-weight compounds and oligosaccharide haptens. With different levans,Ka values ranged from 1.14 X 10(5) TO 1.52 X 10(6) ML/g for PC 3660, 1.35 X 10(5) TO 6.45 X 10(5) mL/g for UPC 10, 1.0 X 10(4) to 7.9 X 10(4) mL/g for Y5476, 7.63 X 10(3) to 6.38 X 10(4) mL/g for W 3082, and 3.35 X 10(3) to 1.54 X 10(4) mL/g for UPC 61. The retarded, D-fructan-specific bands of W3082 and UPC 61 were restored by inulin, having beta-D-(2 leads to)-linkages, and rye-grass levan, having beta-D-(2 leads to 6)-linkages, and those of PC 3660, UPC 10, and Y5476 by rye-grass levan. The Kia values of inulin with W3082 and UPC 61 were 10 times those of rye-grass levan. The Kia values of inulin (3.65 X 10(5) M-1 for W3082, and 4.44 X 10(5) M-1 for UPC 61) were very similar to those of [beta-D-Fruf-(2 leads to 1)]2-beta-D-Fruf-(2 leads to 6)-D-Glc (3) (3.95 X 10(5) M-1 for W3082, and 4.5 X 10(5) M-1 for UPC 61). With sucrose and the D-fructo-oligosaccharides, the order of Kia values of W3082 and UPC 61 was 3 greater than beta-D-Fruf-(2 leads to 1)-beta-D-Fruf-(2 leads to 6)-D-Glc greater than sucrose greater than beta-D-Fruf-(2 leads to 6)-D-Glc. With rye-grass levan, Kia values were 4.25 X 10(5) M-1 for PC 3660, 2.7 X 10(5) M-1 for UPC 10, and 8.77 X 10(4) M-1 for Y5476. These results confirm earlier findings that W3082 and UPC 61 have dual specificity for beta-(2 leads to 1) and beta-(2 leads to 6) D-fructofuranosyl linkages, that PC 3660, Y5476, and UPC 1U have specificity for beta-(2 leads to 6) D-fructofuranosyl linkages, and that the combining sites of W3082 and UPC 61 are most complementary to the tetrasaccharide 3. That W3082 and Y5476 share the same, cross-reacting idiotype, although their combining sites differ in specificity, provides further evidence that these two properties do not run parallel.

The genetic and cellular basis of regulation of the immune response to tumor antigens

In this chapter I have dealt with the cellular and genetic basis of regulation of the immune response to tumor antigen. I have knowingly omitted discussion of effectors such as ADCC, NK, and B cells, since my own experience with such effectors relates primarily to early events associated with small-tumor inocula (Greenberg and Greene, 1976). In that model, NK and ADCC mechanisms, in which natural antibody and macrophages participate, are of importance and T cells are not. In the studies I have dealt with herein, more advanced tumor models have been evaluated. It is clear, I hope, from this chapter that understanding the pathways to immune-cell or Ts activation will provide the basis for applied immunotherapy techniques in the future.

Immunochemical studies on dextran-specific and levan-specific myeloma proteins from NZB mice

Two dextran-specific (PC 3858 and PC 3936) and one levan-specific (PC 3660) NZB myeloma proteins were studied by quantitative precipitin and precipitin-inhibition assays. Both myeloma antidextrans were alphaD-(1 leads to 6) specific and precipitated strongly with a synthetic, linear dextran, molecular weight 35,500, and with other dextrans. The two myeloma antidextrans differed with respect to their relative reactivities with dextrans containing various proportions of alpha-D-(1 leads to 6), alpha-D-(1 leads to 4)-like, and alpha-D-(1 leads to 3)-like linkages. In inhibition assays, the two antidextran myeloma proteins behaved differently from each other, from alpha-D-(1 leads to 6)-specific BALB/c myeloma antidextrans, and from the human antidextrans previously studied. Isomalto-oligosaccharides IM3, IM4, and IM5 were all equal in inhibitory power but were only about 60% as potent as IM6 and IM7, which also inhibited equally on a molar basis. Although precipitation with linear dextran suggests that both may have groove-type sites, as previously inferred for QUPC 52, the size of their combining sites is uncertain. It is not clear whether the sites are only as big as three glucose residues with the increased inhibition by six and seven glucose residues being attributable to partial bivalence and to their ability to combine in several ways along the chain, or whether the site is as big as six glucose residues with the increment in binding by the fourth and fifth glucose residues being minimal and the sixth contributing considerable additional binding-energy. The fructan-specific myeloma protein did not react with inulin, but reacted with many levans and with perennial rye-grass levan containing only beta-D-(2 leads to 6) links. The levan-antilevan reaction was not inhibited by beta-D-(2 leads to 1)- linked oligosaccharides. The findings suggest that PC 3660 has a specificity for (2 leads to 6)-linked chains.

Therapeutic studies in NZB/NZW mice. VI. Age-dependent effects of concanavalin A stimulated spleen cell supernate

Spleen cells from normal mice were cultured with Concanavalin A to produce an immunosuppressive supernate. This supernate was used to treat the lupus-like autoimmune disease of NZB/NZW mice. Such treated mice lived significantly longer than did controls, but only if treatment was initiated early in the course of the illness.

Allotypes of IgM and IgD receptors in the mouse: a probe for lymphocyte differentiation

Antibodies to IgD and IgM are present in many mouse alloantisera made against lymphocytes. Antibodies to IgM are also present in a small minority of conventional antiallotype sera made against pertussis/anti-pertussis complexes. These antibodies reflect different allelic forms of IgD and IgM in different mouse strains, and allowed the mapping of the delta- and mu-chain genes (Ig-5 and Ig-6, respectively) to the heavy-chain complex. The variable portions of IgM and IgD receptors on individual cells bearing both chains are similar or identical. Both receptors show allelic exclusion and come from the same chromosome on individual cells (haplotype exclusion). It is suggested that very early in B lymphocyte differentiation there is a commitment to a given chromosome, and translocation of one copy of a given variable region gene to each heavy-chain gene. Subsequent switches of immunoglobulin class then involve differential gene activation. Immature B cells possess IgM receptors only and mature into cells bearing both IgM and IgD receptors. After activation with antigen, IgD is probably lost. These findings are discussed within the framework of the clonal abortion theory of B-lymphocyte tolerance.

Genetic studies in inbred rats. VII. Tentative model for the major histocompatibility complex

Several lines of evidence are presented which support a tentative model of the major histocompatibility complex (MHC) of the rat. The serologically defined (SD), lymphocyte defined (LD) and immune response (Ir) loci are separate but linked, and there are probably two loci controlling the serologically defined antigens. The MHC in the rat appears to resemble that in the human more than that in the mouse.