Brief communication: Transplantable immunoglobulin-secreting tumors in rats. V. Monoclonal immunoglobulins secreted by 250 ileocecal immunocytomas in LOU-Wsl rats

Apoptosis of human naive NK cells mediated by a rat IgG2b anti CD2 mAb through a fractricidal ADCC reaction

LO-CD2a/BTI-322, a rat anti human CD2 mAb, shows in vitro and in vivo immunosuppressive properties and induces T-cell depletion resulting partially from an antibody dependent cellular cytotoxicity (ADCC) mediated by NK cells. The aim of this paper is to study the in vitro effect of LO-CD2a/BTI-322 on NK cells, the majority of them also expressing the CD2 molecule. The addition of the mAb to purified naive NK cells induces apoptosis of CD2+ cells. The apoptosis is rapid, Fas ligand independent and completely inhibited by the calcium chelator EGTA, suggesting a fractricidal ADCC reaction and implying that NK cells are not resistant to lysis when used as target cells. At the end of the reaction, the CD2 - remaining cells are still capable of natural cytotoxicity against K562 cells, but at a lower rate than untreated cells.

Anti-cholera toxin IgA-, IgG- and IgM-secreting cells in various rat lymphoid tissues after repeated intestinal or parenteral immunizations

Single antibody-secreting spot-forming cells (SFC) of the 3 main isotypes were counted in lymphoid cells from the gut lamina propria (LP), Peyer's patches (PP), mesenteric nodes (MN) and spleen (SP) of rats immunized 2-6 times intraduodenally (ID) or intraperitoneally (IP) with cholera toxin (CT). Responses for all isotypes peaked in all tissues after 4 ID- or IP-immunizations at much larger values than previously reported, and significantly decreased thereafter, except in LP and PP after IP-injections, where IgA- or IgG-SFC, but not IgM-SFC, only appeared or increased after 6 IP-doses. The highest IgA-SFC numbers (17% of tested cells) were in LP after 4 ID-doses. The isotype ratio was IgA greater than IgG greater than IgM in LP and PP after ID-injections, but IgG greater than IgA greater than IgM in MN and SP after both ID- and IP-routes. The isotype dispersion was much larger in LP and PP than in MN and SP. Our data show that at least 4 IP CT-doses were required to only elicit a few IgG- and almost no IgA-SFC in LP and PP, outlining the need for intestinal CT-immunizations to induce strong mucosal IgA-SFC responses. We also show good systemic responses elicited both by enteral and parenteral routes, and the small contribution of PP in total SFC, particularly after parenteral immunizations.

Hormonal modulation of sex differences in resistance to Leishmania major systemic infections

Differences in susceptibility to intravenously inoculated Leishmania major were observed in male and female mice of the BALB/cAnPt, DBA/2N, and DBA/2J strains and (BALB/cAnPt x DBA/2N)F1 hybrids. In all cases, males had significantly higher liver parasite burdens than females. Orchidectomy of BALB/c males resulted in a 20% decrease in the number of parasites in the liver compared with either normal or sham-gonadectomized controls. Additionally, testosterone treatment of female BALB/c mice resulted in an 88% increase in the number of liver amastigotes. These results suggest that the hormone testosterone can modulate systemic L. major infections in BALB/c mice.

Synthesis, processing, and secretion of rat immunoglobulin E made in Xenopus oocytes

Rat immunoglobulin E (IgE) synthesized in Xenopus laevis oocytes, injected with rat plasmacytoma mRNA, was analysed by specific immunoprecipitation and SDS-polyacrylamide gel electrophoresis under reducing as well as non-reducing conditions. The results indicate that the oocytes will translate and correctly process the rat IgE heavy and light chains, resulting in secretion of a correctly assembled, normal immunoglobulin molecule. The normal, extensive glycosylation of the IgE heavy chain (e-chain) is faithfully carried out by the oocytes; therefore, this posttranslational modification is apparently of an unspecific nature, and does not depend upon a mechanism specific for plasma cells.

Expression of immunoglobulin lambda chains in the laboratory rat

We immunized a BALB/c mouse with the lambda-bearing rat IgG1 myeloma IR31, fused its spleen cells with the hybridoma parent line P3.X63.Ag8.653, and isolated a monoclonal antibody (G33/11) directed against rat immunoglobulin lambda chains. We used this antibody to classify two existing rat hybridomas as lambda-bearing proteins (D4.37HL.252 and PC61.5), and isolated one new lambda-bearing rat IgM hybridoma, G36/1. All the normal inbred rat sera that were tested contained lambda-bearing Ig as detected by G33/11, at levels ranging from 1.5% to 13% of the total serum Ig, the mean value being 7.9%. This antibody will be valuable for broadening our understanding of the immunogenetics of the rat, and for the characterization of monoclonal antibodies made in this species.

Rat (and mouse) monoclonal antibodies. V. A simple automated technique of antigen purification by immunoaffinity chromatography

A technique to automate the purification of antigens by immunoaffinity chromatography is described. It is operated on a time basis and measurements of the optical density of the immunoaffinity column eluate are made at 280 nm. Immunoaffinity columns of Sepharose 4B coupled mouse or rat monoclonal antibody can be used for 150 or more cycles. From 23 to 120 mg of monoclonal antibody were purified per run. There is a potential application of this system to other forms of affinity chromatography.

Production of monoclonal anti-glomerular basement membrane antibodies during autoimmune glomerulonephritis

Monoclonal anti-glomerular basement membrane (GBM) antibodies were obtained by fusing spleen cells from Brown-Norway (BN) rats injected with mercuric chloride with IR 983 F, a nonsecreting rat myeloma cell line. These antibodies showed the same pattern of fixation on renal basement membranes by indirect immunofluorescence. One of them was developed. It reacted both in vivo and in vitro with GBM but failed to react with collagenase-digested GBM, laminin, and collagen IV. This monoclonal antibody which resembles the kidney acid eluate obtained from BN rats injected with mercuric chloride induced a weak and transient proteinuria when intravenously injected into normal BN rats.

Rat monoclonal antibodies. II. A rapid and efficient method of purification from ascitic fluid or serum

A technique for purifying rat monoclonal antibodies from ascitic fluid or serum is described which is based on 2 facts. First, approximately 95% of rat immunoglobulin light chains are of the kappa type. Second, an allotypy in the rat species is located on the constant part of the kappa light chain. By use of a mouse monoclonal antibody with specific binding affinity for the Ig kappa-1a allotype on the kappa light chains of the LOU inbred rat strain, it is possible with immunoaffinity chromatography to isolate LOU Ig kappa-1a-bearing immunoglobulins from the serum proteins, including the immunoglobulins, of rats of Ig kappa-1b allotype. LOU histocompatible hybridomas synthesizing the Ig kappa-1a allotype can be transplanted into rats congenic with the LOU inbred strain carrying the Ig kappa-1b allotype, since LOU rats with the Ig kappa-1a kappa light chain allotype and congenic LOU Ig kappa-1b rats with the Ig kappa-1b kappa light chain allotype are fully histocompatible. The serum or ascitic fluid of the recipients is applied to an immunoabsorbent column to which mouse monoclonal antibody against the Ig kappa-1a allotype is coupled. The serum proteins, including the host immunoglobulins pass through the column. An appropriate buffer is used to elute the monoclonal antibodies in a second step. The same technique may be employed for other monoclonal antibodies. A reciprocal system using mouse monoclonal antibodies against Ig kappa-1b rat allotype can be used, a plasmacytoma or hybridoma synthesizing Ig kappa-1b kappa light chain being transplanted into an Ig kappa-1a kappa light chain synthesizing rat. The method is rapid, efficient and inexpensive. Its limitation is with respect to lambda-type monoclonal antibodies, which are relatively rare.

Rat monoclonal antibodies. I. Rapid purification from in vitro culture supernatants

A technique for purifying rat monoclonal antibodies quickly and efficiently from in vitro culture supernatants is described. It is based on the fact that more than 95% of rat immunoglobulins carry kappa light chains. A mouse monoclonal antibody with suitable binding affinity for rat kappa light chains is immobilized on solid support and used to purify rat immunoglobulins. Milligrams of rat monoclonal antibodies may be rapidly concentrated from culture supernatants with high recovery. Rat monoclonal antibodies expressing lambda light chains (about 5% of the total) may be purified in a similar way with an appropriate anti-rat lambda chain monoclonal antibody.

Subclass restriction of the antiidiotypic antibody response in the rat

Antiidiotypic antibodies were induced in LOU/M rats by immunization with two myeloma proteins of LOU origin: IR-162 (IgE) and IR-418 (IgG2a). Antibodies to IR-162 were easily obtained after a limited number of immunizations with protein in soluble form; polymerization with glutaraldehyde did not enhance immunogenicity. Antibodies to IR-418 appeared only after a large number of immunizations with protein in polymerized form or with protein copolymerized with rabbit IgG. All of the antibodies, either to IR-162 or to IR-418, were found to be idiotype-specific. In every case for which significant levels of antiidiotypic antibodies were produced, most or all of the antibodies belonged to rat IgG1 subclass. Since, in mice, antiidiotypic antibodies are restricted to the IgG1 subclass, our results indicate a functional analogy between rat and mouse IgG1. Our studies also suggest that the rat IgG1 subclass may be predominantly expressed in T-cell-dependent antibody responses, such as production of antiidiotypic antibodies.

Rat hybridoma antibodies against canine parvovirus

Hybrid cells have been produced by fusion between rat myeloma cells IR983F and spleen cells from a LOU rat immunized with canine enteritis parvovirus. Four stable cell lines were selected each secreting a monoclonal antibody directed against this virus. By indirect immunofluorescence, the antigenic determinants recognized by these antibodies were found to be present not only in canine parvovirus infected cells but also in cells infected by the related parvoviruses of mink enteritis and feline panleukopenia. Two of the monoclonal antibodies inhibit hemagglutination by the canine virus and neutralize its infectivity. Hybrid cells were transplanted into histocompatible animals, and large amounts of the antibodies were obtained.

Solubilization and initial biochemical characterization of an IgE-destroying enzyme on rat peritoneal mast cells

Previous studies had demonstrated that incubation of IgE with purified rat mast cells can result in the time and cell concentration-dependent destruction of the ability of the IgE to be bound to specific receptors on rat basophil leukemia cells. The IgE-destroying activity, which has an extremely acid pH optimum, resisted attempts at solubilization using detergents. However, it was solubilized in good yield by use of chaotropic salts and especially KOCN. The soluble activity is stable to freezing and thawing, and to heating to 68 degrees C for 60 min. It is promptly destroyed upon boiling. IgE destruction was linear with time up to 20 min and a series of products, mol. wts 138,000, 92,500, 60,000 and 36,500, are formed during the reaction. No pH optimum for the reaction could be found because, as the pH was lowered below 4.0, the spontaneous destruction of IgE became too great. At pH 4.75 the apparent Km for the reaction was 0.55 microM and Vmax was 0.4 nmoles IgE/10(4) mast cell equivalents/min. IgE-destroying activity could be inhibited by heat-inactivated serum, and by relatively high concentrations of crude alpha 1-antitrypsin, aprotinin, lima bean and soybean trypsin inhibitors and by p-nitroguanidinobenzoate. A large number of other protease inhibitors were inactive.

Non-random chromosomal changes involving chromosomes 6 and 7 in spontaneous rat immunocytomas

G-banding analysis of seven Ig-secreting spontaneous rat immunocytomas showed a consistent translocation of the distal part of the q-arm of chromosome 7 to the telomeric end of chromosome 6. The breakpoints were assigned to q3.3 on chromosome 7 and q3.2 on chromosome 6. Previously, we found a similar translocation pattern in mouse plasmacytomas induced by different agents. The distal part of the q-arm of chromosome 15 was translocated to the telomeric end of chromosome 12, known to carry Igh, the immunoglobulin heavy chain cluster. The banding homologies between the chromosomes involved in the translocation in the two species suggest that a similar mechanism is responsible for plasmacytomagenesis in both. We also predict that the rat Ig heavy chain gene cluster will be located to the terminal segment of chromosome 6.

Comparative study of the conformational features of rat immunoglobulin G subclasses by circular dichroism

Four subclasses of rat immunoglobulin G and some of their fragments were studied by circular dichroism. These studies were carried out in different conditions in order to determine whether conformational differences exist between each subclass. The results showed that in their native state the subclasses cannot be distinguished by characteristic differences. Moreover, differences between monoclonal immunoglobulins G of the same subclass were found, particularly in the 200-250 nm region, and their relationship to aromatic side chain contributions (especially those of tyrosine) has been investigated. However, the conformations of the immunoglobulin G were found to be differently affected by denaturing treatments and a relation to subclass has been demonstrated.

A sensitive enzyme-linked immunosorbent assay for the quantitation of antigen-specific murine immunoglobulin E

An enzyme-linked immunosorbent assay (ELISA) for the quantitation of 2,4-dinitrophenyl (DNP)-specific murine immunoglobulin (Ig) E is described. The assay uses beta-galactosidase, which is conjugated to goat anti-rabbit gamma-globulin (GARG) via a method using a mild heterobifunctional cross-linking reagent, m-maleimidobenzoyl-N-hydroxy-succinimide ester (MBS). The assay has a sensitivity for detection of about 200 pg/ml of anti-DNP IgE. Analyses of murine serum samples using this ELISA correlate well with those obtained using the passive cutaneous anaphylaxis (PCA) reaction in rats. With the use of automated 96-well reader, data acquisition is rapid and, therefore, this ELISA is ideal for analyses of large numbers of samples. The assay can be easily modified for the measurement of other Ig classes and of IgE of other antigen specificities.

Effect of sensitization and non-antibody IgE on 48/80 induced histamine release from isolated rat mast cells

Histamine release from isolated rat mast cells from non-immunized and immunized Hooded Lister rats was induced by compound 48/80. The histamine release was decreased with a lower maximum at the optimal concentration of 48/80 when using cells from immunized rats compared to non-immunized control rats. The stimulation of IgE antibody production, after immunization using B. pertussis as an adjuvant was also accompanied by an elevation of total serum IgW. The 48/80 induced histamine release from Sprague Dawley mast cells was not inhibited by immunization. Non-antibody IgE showed a non-competitive inhibition of 48/80 induced histamine release when myeloma IgE was incubated with mast cells from both Hooded Lister and Sprague Dawley rats. The results indicate the existence of different receptors for IgE and 48/80.

IgE production in vitro by two rat myeloma tumor lines (IR2 and IR162)

Two IgE-synthesizing rat myeloma tumor lines (IR2 and IR162) were maintained in growing cultures that were viable for prolonged periods of up to three months in the presence of primary fibroblasts. The production of IgE by explanted tumor cells was studied in short-term and long-term cultures. The IR 162 tumor line retained expression of both IgE heavy (H) and light (L) chain synthesis for up to three months under in vitro conditions, while the IR2 tumor line initially lost H chain expression after approximately one month in culture, followed by subsequent loss of L chain about one month later. Total polysomal RNA extracted from IR2 cells, before and after loss of IgE-expression, was separated by sucrose gradient centrifugation, and gradient fractions were analysed for poly(A)-containing mRNA by a [3H]poly(U)binding assay. The results for the long-term IR2 cultures showed a disappearance of mRNA sedimenting at 18-20 S and 15 S, found to represent H and L chain mRNAs, respectively. Furthermore, no IgE L chain mRNA sequences could be detected in long-term IR2 cultures when analysed by hybridization assays, using as a probe a 3H-labelled DNA complementary to IgE L chain mRNA, L chain mRNA sequences were also absent from the nuclear RNA in long-term IR2 cultures. The loss of IgE synthesis in long-term cultures of IR2 cells therefore appears to be correlated with a concomitant loss of IgE mRNA sequences indicating a dedifferentiation in vitro modulated at the transcriptional level.

Total serum IgE influence on the anaphylactic and 48/80 induced histamine release from isolated rat mast cells

We have investigated the influence of non-specific IgE on histamine release induced by antigen or compound 48/80. Our results indicate that increased amounts of IgE influence antigen mediated histamine release as well as release induced by a non-immunological stimulus like compound 48/80.

Studies on the incidence of rat ileocecal malignant immunocytoma: vertical transmission of the high tumour incidence

Monoclonal immunoglobulin-secreting tumours (immunocytomas, myelomas or plasmocytomas) appear with a high or low incidence in 2 sublines, LOU/C and LOU/M respectively, of the same inbred strain of rats. Studies of the reciprocal hybrids of the first generation between both substrains have shown that the transmission of the high tumour incidence from parents to offsprings is determined by the male as well as by the female. Absence of C-type viral particles in LOU/C rats and immunocytomas derived from them suggests that this vertical transmission might be genetically mediated.

Relationship between serum IgE levels and anaphylactic histamine release from isolated rat mast cells

Inbred Hooded Lister rats were immunized with egg albumin with B. pertussis vaccine used as an adjuvant. The serum levels of total IgE and IgE antibody (egg albumin specific) were determined by radioimmunoassay techniques before and after immunization. The basic level of total IgE in serum was 560 +/- 110 ng/ml. After immunization a maximal peak at day 11 of 1940 +/- 160 ng/ml was registered. Anti-egg albumin IgE antibody showed a maximum around day 13 of 75 +/- 11 units/ml. Pleural mast cells were isolated on Ficoll between day 14 and 20 after immunization. A significant negative correlation between the basic total IgE level and histamine release by antigen (egg albumin) was found and also a significant positive correlation of specific IgE antibody (determined at day 11) and histamine release. The correlation between IgE level and histamine release was slightly improved if instead the ratio of specific IgE antibody over total IgE was used.

Rat immunoglobulins

Five immunoglobulin isotypes (or classes) have been identified in the human as well as in the rat species. The homologies between the human and the rat immunoglobulin classes have been well defined with the help of the monoclonal immunoglobulins produced by the LOU immunocytomas (plasmocytomas,myeloma tumours). The LOU rat immunocytomas model, the physicochemical and the biological properties of the rat immunoglobulins are described in this review.

Decrease in the incidence of malignant ileo-caecal immunocytoma in LOU/C rats after surgical removal of the ileo-caecal lymph nodes

Malignant ileo-caecal immunocytomata, which secrete immunoglobulin, frequently arise spontaneously in LOU/C/Wsl rats. The tumors are confined to the ileo-caecal region and could originate either in the wall of the caecum or in the ileo-caecal lymph nodes. After excision of the ileo-caecal lymph nodes, the incidence of the type of tumor was found to be reduced significantly. The results strongly suggest that the first cells to undergo malignant transformation are located in the ileo-caecal nodes.

Partial amino acid sequences of kappa-chains of rat immunoglobulins: genetic and evolutionary implications

Partial amino acid sequences have been determined for several kappa-type light chains prepared from sera or urine of inbred LOU/C/Wsl rats bearing plasma cell tumors. Comparison of these sequences with those of human, rabbit, and mouse kappa-chains available in the literature indicates that the constant region of rat kappa-chains shows more amino acid sequence homology to that of the mouse kappa-chain than to human and rabbit kappa-chains, a result expected from the phylogenetic relationship of the species compared. Examination of the N-terminal amino acid sequences indicated that the variable regions of rat kappa-chains can also be classified into subgroups according to degree of sequence homology in a manner similar to that done for kappa-chains of other species (e.g., human, rabbit, and mouse). However, the prototype amino acid sequences of kappa-chain variable region subgroups of the rat were not homologous to those of other species including the closely related mouse. The implications of this observation with respect to the genetics and evolution of immunoglobulins are discussed.

Isolation and properties of a 7 S rat immunoglobulin different from IgG

A 7 S rat immunoglobulin, of rapid electrophoretic mobility, was characterized and isolated from normal or hyperimmune rat serum and was designated "IgR". This immunoglobulin belongs to a class different from IgG and was originally described as IgA. IgR has a molecular weight of 160 000, is present in the serum and milk as a monomer and is readily absorbed by the intestine of suckling rats. In hyperimmunized animals, about 20% of the antibodies were of the IgR class. IgR is devoid of anaphylactic capacity and no homologies could be established between it and immunoglobulins of other animal species.