Mouse Ascitic Fluid Research Articles

Molecular variants of β2-microglobulin in renal insufficiency

Many patients with renal insufficiency treated by dialysis for more than 10 years have tissue deposits of amyloid material containing polymerized beta 2-microglobulin (beta 2m). The mechanisms of beta 2m polymerization and degradation remain unknown. In biological fluids (serum and urine) from haemodialysis patients and in dialysis fluids from patients treated by chronic ambulatory peritoneal dialysis (CAPD), we have characterized different molecular forms of beta 2m, including proteolytic split products. beta 2m isoforms of pI 5.7, 5.3 and 4.5-5.0 were isolated from urine and CAPD fluid. The pI 5.3 beta 2m, but not the other forms, was recovered both as monomers and as dimers. Such dimers were also detected in serum from patients but not from healthy controls. pI 5.3 and 5.7 beta 2m isoforms were found to be nearly identical by mass spectrometry and by their amino acid sequences. The amino acid sequence of the 43 N-terminal amino acids of beta 2m of pI 5.0 showed identity with the corresponding region of pI 5.7 beta 2m. Fragments recovered from CAPD fluid were similar to proteolytic fragments generated from pure pI 5.7 beta 2m by incubation in mouse ascitic fluid at acidic pH. Furthermore, pure pI 5.7 beta 2m was converted into more acidic forms of 12 kDa upon incubation in mouse ascitic fluid at acid pH. beta 2m dimers found in serum may represent a precursor of amyloid fibrils.

Some ascites monoclonal antibody preparations contain contaminants that bind to selected Golgi zones or mast cells.

A small proportion of mouse ascites fluid induced by hybridomas producing monoclonal antibodies or myelomas secreting immunoglobulin yielded staining that was confined to the Golgi zone of certain epithelial cell types in rats and gerbils but not in mice. In addition, a commercial IgG fraction from mouse plasma similarly labeled the Golgi area, unlike IgG from mouse serum from another source. Culture supernatant from one hybridoma line contrasted with ascites fluid produced by the same hybridoma in failing to stain the Golgi region. The capacity of a fluid to react with the Golgi cisternae bore no relationship to the class of immunoglobulin secreted by the hybridoma or myeloma. Absorption of an ascites fluid with blood group A1 human erythrocytes eliminated its affinity for Golgi cisternae. Adsorption with blood group A2 or B or two type O cells used for screening for blood group antibodies had no effect on Golgi zone labeling by this ascites fluid. The positive cells included most serous secretory cells in rats, serous cells of sublingual and tracheal glands, and some endometrial and oviduct-lining cells in gerbils, and columnar lining cells of small intestine and cecum and all or part of the lining cells in some prostate lobes in both genera. Some of the tested ascites fluids stained mast cells. The agent accounting for mast cell labeling differed, however, from that reacting with Golgi cisternae in its distribution among the mouse ascites fluids examined, lack of relationship to the ABO blood group system, occurrence additionally in normal rat serum, and capacity to stain cells in mice as well as rats and gerbils.

St Louis encephalitis virus establishes a productive, cytopathic and persistent infection of Sf9 cells

The Sf9 cell line, commonly used for gene expression by recombinant baculovirus, has been productively infected by St Louis encephalitis (SLE) virus, a flavivirus. SLE viral infection produced a c.p.e. in the Sf9 cells characterized by giant cells and the presence of 10-fold fewer cells in the infected cultures after the first week of infection compared with uninoculated control cultures. Infected Sf9 cells expressed SLE viral antigens, and intracellular virus particles were observed by electron microscopy. Titres of cell-associated SLE virus rose slightly over an 8 week period, whereas titres of cell-free virus remained stable, suggesting that SLE virus establishes a productive and persistent infection of Sf9 cells. The SLE virus produced by the Sf9 cells could be neutralized by SLE virus-immune mouse ascitic fluid, and no evidence of escape mutants was detected. Sf9 cells persistently infected with SLE virus could be superinfected with a recombinant baculovirus and expressed recombinant antigen. The successful infection of Sf9 cells by SLE virus represents the first report of production of c.p.e. by SLE virus in insect cells under routine cell culture conditions and of the infection of Sf9 cells by a human pathogen.

Development of a competitive enzyme-linked immunosorbent assay for detection of bovine, ovine, porcine, and equine antibodies to vesicular stomatitis virus

Two competitive (C) enzyme-linked immunosorbent assays (ELISAs) were developed for the detection of antibodies to vesicular stomatitis virus (VSV) in animal sera. The assays are based upon the availability of polyclonal antibodies (PAbs) from mouse ascitic fluids prepared against the New Jersey (NJ) and the Indiana (IN) VSV serotypes. The assays were performed by the immobilization of VSV-NJ and VSV-IN antigens on a solid phase (microtiter plate). Appropriately diluted test serum mixed with an equal volume of serotype-specific PAb was allowed to incubate in the presence of the relevant VSV antigen and finally with an enzyme-conjugated anti-mouse immunoglobulin. In the absence of anti-VSV antibodies in the test serum, the VSV antigen sites are reactive with the relevant PAb (NJ or IN) as indicated by color development after enzyme degradation of substrate. If the test serum contains the homologous VSV-NJ or VSV-IN antibodies, they compete with the relevant PAb for immobilized antigen sites and quantitatively block and inhibit the PAb reaction and subsequent color development. The performance of C-ELISAs in detecting anti-VSV antibodies in serum samples from four calves, two horses, four sheep, and seven pigs experimentally infected with VSV-NJ and VSV-IN was evaluated. The sensitivity and specificity of the C-ELISAs were compared with those of the standard microtiter serum neutralization (MTSN) tests. Homologous antibodies were demonstrable by C-ELISAs as early as 5 days postinfection (DPI) in one horse and one sheep infected with VSV-IN serotype. Seroconversion was demonstrable by C-ELISAs and MTSN tests in all animals by 9 DPI except in one sheep that received VSV-NJ and one horse inoculated with VSV-IN serotype which, on the basis of the MTSN test results, did not seroconvert until 14 and 11 DPI, respectively. The dynamics of homologous antibody response in all animals as revealed by the corresponding type-specific C-ELISAs paralleled the results of the MTSN tests. The type-specific antibodies to VSV serotypes increased exponentially during the first 2 to 4 weeks postinfection and remained relatively stable for about 6 months in some animals. The results suggest that the C-ELISAs offer many advantages over the MTSN tests and have potential applications as rapid and inexpensive tests in serodiagnosis of VSV infections in animals.

Activity of the carbapenem panipenem and role of the OprD (D2) protein in its diffusion through the Pseudomonas aeruginosa outer membrane

Evidence of permeation of panipenem through the OprD (D2) channel of Pseudomonas aeruginosa outer membrane was shown by using OprD protein-producing and -nonproducing strains which contained plasmid pHN4, which codes for L-1 beta-lactamase of Xanthomonas maltophilia. Permeation by panipenem was determined by measuring hydrolysis of the carbapenem by beta-lactamase in the periplasmic space. Permeation by panipenem was also determined by counting uptake of [14C]panipenem into P. aeruginosa PAO1 and its OprD protein-deficient mutant, and this permeation of PAO1 was inhibited by L-lysine. These results indicate that panipenem, as well as imipenem, uses the OprD channel, which functions as a specific channel for diffusion of basic amino acids. Panipenem and imipenem showed stronger activities against PAO1 and clinical isolates in human serum than in Mueller-Hinton broth, which contains more amino acids than human serum does. The activities of the carbapenems were reduced by addition of L-lysine to human serum. Similar results were obtained with mouse serum and ascitic fluid. In contrast, such a change in the activities of carbapenems was not observed with an OprD protein-deficient mutant, suggesting that the main reason for the strong activities of carbapenems in biological fluids is a decrease in competition between the antibiotics and basic amino acids for permeation through the OprD channel. Panipenem and imipenem showed much stronger therapeutic efficacies against experimental infections with P. aeruginosa in mice than did the reference antibiotics. Their in vivo activities were more consistent with their MICs in biological fluids than with those in Mueller-Hinton broth.

EVIDENCE INCONSISTENT WITH A ROLE FOR TUMOR NECROSIS FACTOR IN TUMOR ALLOGRAFT REJECTION

Since it has been suggested that tumor necrosis factor is involved in organ allograft rejection, experiments were undertaken to determine whether it is involved in the rejection of allogeneic P815 tumor cells growing as ascites in the peritoneal cavities of mice. The results show that biologically active TNF was not detectable in serum or ascites fluid of mice during either growth or vigorous rejection of the tumor. On the other hand, mice in the process of rejecting their ascites tumor displayed a greatly enhanced capacity to produce TNF in the peritoneal cavities and systemically in response to an injection of endotoxin i.p. These results show that the immune response to the tumor was associated with the priming of host cells for increased TNF production both locally and systemically in response to an appropriate stimulus that was not supplied during the generation and expression of immunity. Additional evidence against a role for TNF in ascites tumor allograft rejection is seen in the finding that i.p. administration of anti-TNF antibodies failed to interfere with elimination of allogeneic tumor cells, even though the antibodies were given repeatedly before and during the rejection process. Taken together, these results are inconsistent with the view that TNF is involved in the effector stage of the anti-allograft response, even though cells at the site of rejection are primed to produce large quantities of TNF in response to endotoxin.

Immunological properties of a radioiodinated monoclonal antibody and its F(ab')2mu fragments directed against the polymorphic epithelial mucin of human breast cancer.

The purification of the IgM monoclonal antibody 436 against a breast tumor antigen from mouse ascitic fluid is reported. The purified immunoglobulin was radioiodinated and the resulting product assessed for its binding capacity and binding specificity. Purified IgM-436 served for F(ab')2 mu preparation which was tested for its antigen binding capacity. Radioiodinated IgM-436 and its F(ab')2 mu retained their immunological activity which was never lower than those of the corresponding cold products.

Production of polyclonal antibodies in ascitic fluid of mice: time and dose relationships.

Further studies of the humoral immune response have been undertaken using ovine immunoglobulin G as the immunogen and BALB/C mice as the recipients. Mice immunized by the intraperitoneal route weekly for five weeks with an emulsion of the immunogen in Freund's complete adjuvant and given an intraperitoneal injection of pristane on day 14 produce relatively large volumes of ascitic fluid. A simple fluoroimmunoassay is used to determine specific antibody titres. The mice do not lose condition, remain active and eat normally throughout, although all show extensive granuloma formation within the peritoneal cavity. Tapping is performed before ascitic fluid production is excessive and each study is complete within 49 days, with a maximum of 5 taps. Only a single immunization site is required, since no higher antibody titres are obtained using combined intraperitoneal plus intramuscular plus subcutaneous immunization routes. A dose response study has shown that relatively large amounts (100 micrograms) of ovine immunoglobulin G must be injected to evoke a maximum response. Studies are in progress of various adjuvants and potential modulators of the immune response and of ways in which the immunogenicity of macromolecules can be changed. This approach can also be used to obtain antibodies for diagnostic purposes more rapidly than in rabbits and sheep.

Selection of an escape variant of Borrelia burgdorferi by use of bactericidal monoclonal antibodies to OspB.

Two immunoglobulin G (IgG) monoclonal antibodies (MAbs) to outer surface protein B (CB2 and CB6), affinity purified from mouse ascitic fluid, exhibited concentration-dependent inhibitory and bactericidal properties against Borrelia burgdorferi after a 24-h incubation period in spirochete medium. Fab fragments derived from these MAbs showed the same effects, indicating that they were not caused by agglutination of the organisms by the intact MAbs. The inhibition of spirochete growth in cultures containing MAbs was also detected by spectrophotometric analysis of the media. CB2 did not inhibit the growth of Borrelia hermsii or the BEP4 strain of B. burgdorferi, neither of which is recognized by the MAb. Affinity-purified IgG from hybridoma supernatants had similar effects on B. burgdorferi as the ascitic-fluid-derived IgG did, indicating that the inhibitory and bactericidal properties were not due to nonspecific toxic contaminants. The bactericidal properties of the MAbs were not complement dependent as there was none in the serum-free system. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of B. burgdorferi organisms surviving after exposure to CB2 revealed an escape variant which failed to express OspB. The continued presence of OspA in these escape variants indicates that the lack of OspB was not due to the loss of the plasmid which contains the genes for both of these proteins.

A blocking ELISA for the detection of specific antibodies to bovine ephemeral fever virus

A blocking ELISA (B/ELISA) for detecting antibodies to bovine ephemeral fever virus (BEFV) in cattle is described. In this test, the binding capacity of a monoclonal antibody specific for an epitope on antigenic site G1 of the BEF virus glycoprotein is blocked in the presence of positive serum. The sensitivity of the B/ELISA was compared with the virus neutralisation (VN) test using a total of 380 sera from cattle. Of these, 118 were from an area known to be free of bovine ephemeral fever, 181 from naturally and experimentally BEFV-infected cattle, 33 sequential serum samples from a sentinel steer from which Berrimah virus (BERV) had been isolated, 9 from a sentinel cow from which Kimberley virus (KIMV) was isolated and a panel of 39 sera supplied as a blind trial. The B/ELISA results overall compared favourably with those of the VN tests. The monospecificity of the test was demonstrated using hyperimmune mouse ascitic fluid to other BEF serogroup viruses, namely KIM and BER viruses and the results showed no significant cross-reaction. The greater simplicity and sensitivity of the test when compared with the VN test makes it the preferred test for the diagnosis and monitoring of clinical bovine ephemeral fever.

Selective high-performance liquid chromatographic purification of bispecific monoclonal antibodies

The recent development of improved production techniques for bispecific monoclonal antibodies (biMAbs) has significantly increased interest in specific purification procedures. In this investigation, a general high-performance liquid chromatographic (HPLC) purification method is proposed that allows highly purified biMAbs to be obtained from mouse ascites fluid containing a mixture of different antibodies, i.e., parental MAbs, active biMAb and a mixture of randomly assembled heavy and light chains. Proteins from ascites fluid were precipitated with ammonium sulphate and applied to a high-performance protein A column to separate the total immunoglobulin fraction. BiMAbs were isolated from other immunoglobulins by two subsequent passages through a high-performance hydroxyapatite (HPHT) column. This purification protocol combines specificity of protein A for immunoglobulin G (IgG) and high selectivity of hydroxyapatite for different IgG idiotypes. All purification steps were performed rapidly and reliably by HPLC. This method was applied to the purification of six different biMAbs with consistently high yields, purity and homogeneity. This general purification method may prove extremely valuable when highly pure preparation of biMAbs is required, as for in vivo use.

Preparation and characterization of Salmonella H antibodies in mouse ascites fluid

A method is described for raising antibodies to Salmonella H antigens in mice. Quantities of high titre antibodies of specificities similar to the traditional methods using rabbits are obtained.

Production of Monoclonal Antibody in Mouse Ascitic Fluid with Two Solid Tumor-Forming Hybridoma Cell Lines

Production of Monoclonal Antibody in Mouse Ascitic Fluid with Two Solid Tumor-Forming Hybridoma Cell Lines

Carboxy-terminally truncated dengue virus envelope glycoproteins expressed on the cell surface and secreted extracellularly exhibit increased immunogenicity in mice

Recombinant vaccinia viruses expressing C-terminally truncated E's that ranged in length from 9 to 99% of the N-terminal sequence were constructed. The overall antigenicity of the E products was analyzed by radioimmunoprecipitation, using dengue virus hyperimmune mouse ascitic fluid (HMAF) or an anti-E peptide serum. Truncated E that was 79% or less in length did not bind HMAF efficiently, whereas E constructs greater than 79% were able to bind HMAF with high efficiency. The first 392 amino acids of the dengue type 4 virus E sequence, including the Arg-392 following the 79% E C terminus, appeared to be critical for proper antigenic structure required for efficient binding by HMAF. Truncated E's ranging from 59 to 81% in length were secreted extracellularly, whereas smaller or larger E's were retained intracellularly. Secreted E's contained carbohydrate side chains that were resistant to endoglycosidase H digestion, suggesting that the transport of E occurs via a pathway from the rough endoplasmic reticulum through the Golgi complex. 79% E-RKG (which possessed the three additional amino acids immediately downstream of 79% E) was expressed at a high concentration on the surface of recombinant virus-infected cells presumably being inserted into the plasma membrane by a hydrophobic C-terminal membrane anchor. Evaluation in mice of the protective efficacy of the various vaccinia virus E recombinants indicated that only truncated E's that were recognized efficiently by HMAF induced a high level of resistance to dengue virus encephalitis. 79% E-RKG which is expressed at a high concentration on the surface of infected cells was highly immunogenic when tested for induction of an E antibody response. This suggests that cell surface expression of 79% E-RKG was responsible for its enhanced immunogenicity. Finally, passive immunization studies indicated that serum antibodies to E played a major role in the complete or nearly complete resistance to dengue virus challenge induced by certain vaccinia virus-truncated E recombinants.

Pharmacological Modulation of the Antigen-Induced Expression of the Low-Affinity IgE Receptor (FcεRII/CD23) on Rat Alveolar Macrophages

Brown-Norway (BN) rats were sensitized by 3 aerosol exposures to ovalbumin (OA; 10 mg/ml) at days 1, 3 and 14. At day 21, the rats were challenged with the antigen or vehicle by aerosol. Alveolar macrophages (AM) were obtained by bronchoalveolar lavage and the expression of Fc epsilon RII/CD23 was assessed by flow cytometry after staining with the BB10 monoclonal antibody. A maximum of 74% of the AM from sensitized and challenged BN rats expressed FC epsilon RII/CD23 24 h after OA exposure, compared to 12% of the cells from rats exposed to vehicle. Sprague-Dawley rats were passively sensitized by intravenous injection of 0.1 or 0.05 ml/kg mouse ascitic fluid containing dinitrophenyl (DNP)-specific monoclonal IgE (2682-1) and after 24 h exposed to an aerosol of 5 mg/ml of DNP-bovine serum albumin for 30 min. In this case also, antigen exposure induced the expression of Fc epsilon RII/CD23 on 75% AM, compared to 17% AM from saline-challenged rats. Such an induction of Fc epsilon RII/CD23 on AM was, however, not observed when the animals were challenged with either histamine, serotonin or acetylcholine by aerosol. The antigen-induced expression of Fc epsilon RII/CD23 on AM was inhibited upon treatment of the rats with ketotifen or beclomethasone. In addition, oral or aerosol administration of respectively BN 50730 or BN 52021 (two structurally unrelated platelet-activating factor antagonists), inhibited the antigen-induced Fc epsilon RII/CD23 expression on AM, indicating the participation of this lipid mediator in this process.

Enhancement of Clot Lysis In Vitro and In Vivo with a Bispecific Monoclonal Antibody Directed against Human Fibrin and against Urokinase-Type Plasminogen Activator

A hybrid hybridoma (FU1-74), secreting a bispecific monoclonal antibody (bs mAb), was obtained by fusion of a murine hybridoma secreting a monoclonal antibody (mAb) specific for human fibrin with a murine hybridoma secreting a mAb against urokinase-type plasminogen activator (u-PA). The bs mAb (MA-FU1-74), purified to homogeneity from mouse ascitic fluid, migrated as a single band with apparent Mr 150,000 on nonreduced SDS-PAGE and had an affinity for both human fibrin (Ka = 2 x 10(7) M-1) and for u-PA (Ka = 10(8) M-1) comparable to that of the mAbs obtained from the respective parental hybridomas. MA-FU1-74 did not influence the enzymatic activity of two-chain u-PA (tcu-PA) towards plasminogen or towards a chromogenic substrate. The complex of MA-FU1-74 with recombinant single chain u-PA (rscu-PA) or with tcu-PA (urokinase) enhanced the fibrinolytic potency of the plasminogen activator towards clotted human plasma 20-fold and 5-fold, respectively. In a hamster pulmonary embolism model, the rscu-PA/MA-FU1-74 complex had a 13- to 17-fold increased thrombolytic potency (percent lysis per mg/kg u-PA administered) relative to that of rscu-PA. The specific thrombolytic activity (percent lysis per microgram/ml steady state plasma level of u-PA antigen) of the complex was, however, not significantly different from that of rscu-PA. The complex of rscu-PA with the parental anti-u-PA mAb (MA-UK1-3) had only a 2-fold enhanced thrombolytic potency relative to that of rscu-PA and had a 5-fold decreased specific thrombolytic activity. The plasma clearance rates of the complexes of rscu-PA with both MA-FU1-74 and MA-UK1-3 were about 10-fold lower than that of rscu-PA. In a rabbit jugular vein thrombosis model, the rscu-PA/MA-FU1-74 complex had a 4-fold enhanced thrombolytic potency, an unchanged specific thrombolytic activity and 20-fold reduced plasma clearance. In both animal models, the rscu-PA/MA-FU1-74 complex did not cause more extensive systemic activation of the fibrinolytic system than rscu-PA. It is concluded that the bispecific anti-fibrin/anti-u-PA mAb MA-FU1-74 targets u-PA to the fibrin clot, resulting in a significantly enhanced thrombolytic potency of the plasminogen activator.

Interleukin 2 Induces Tumor Necrosis Factor Gene ExpressionIn Vivo

Interleukin 2 (IL-2) treatment of malignancies is often associated with severe toxicity, and the alterations observed after high dose administration of IL-2 are similar to those induced by recombinant tumor necrosis factor (TNF). We therefore examined the hypothesis that IL-2 induces TNF gene expression in vivo. Purified, recombinant human IL-2 was injected intraperitoneally into mice which had been previously primed with complete Freund's adjuvant (CFA). Biologically-active TNF was detected in the ascites fluid of CD-1 mice; it was detectable 30 minutes after IL-2 and peaked at 1 hour (500 +/- 158 units/ml). Plasma levels of TNF also peaked at 1 hour at 32 +/- 4 units/ml. Similar kinetics were observed in CBA/J mice. TNF specific mRNA was also present in the ascites cells, and peaked 30 minutes after IL-2 injection into CBA/J mice. Injection of vehicle containing 10 times the maximum contaminating dose of endotoxin did not induce TNF above background levels. As a further control for potential endotoxin contamination, IL-2 was injected into endotoxin hyporesponsive C3H/HeJ mice. These mice also demonstrated the rapid upregulation of biologically-active TNF in the ascites, with peak production occurring at 1 hour (125 +/- 47 units/ml). The induction of biologically-active TNF in the C3H/HeJ mice was associated with a peripheral blood neutrophilia and lymphopenia, pathophysiologic alterations that have been attributed to TNF. These data show that a single injection of purified, recombinant IL-2 induces TNF gene expression in vivo.

Diagnostic use of Polyclonal Antibodies Raised in Mouse Ascitic Fluid in Bancroftian Filariasis

Polyclonal antibodies were produced against Brugia malayi adult antigens (BmA (PBS) SAg and BmA (SDS) SAg) in mouse ascitic fluid by immunising Balb/c mice intraperitoneally with high ratio of adjuvant to immunogen. The diagnostic use of these antibodies in detecting circulating filarial antigen in bancroftian filariasis was studied by sandwich enzyme-linked immunosorbent assay (sandwich ELISA) using stick assay system. Both antibodies raised against PBS and SDS soluble antigens were found to be equally sensitive and relatively specific in detection of circulating filarial antigen. When anti BmA (PBS) SAg antibody was used in sandwich ELISA, 90% of microfilaraemic sera, 30-40% of acute and sub acute filarial sera, 20% of chronic filarial sera, 7% of endemic normal sera and none of 15 non-endemic normal sera were positive for filarial antigen. Using anti BmA (SDS) Sag antibody, 93% of microfilarial sera, 40% of acute and sub acute filarial sera, 20% of chronic filarial sera and none of 15 endemic and non-endemic normal sera showed the presence of filarial antigen. The filarial antigen detection using anti BmA S Ag antibodies produced in mouse ascitic fluid in sandwich ELISA may be useful in detection of active stage (microfilaraemia) of infection.

Isolation of Trichinella-Specific Antigens for Diagnosis by Gradient Monoclonal Antibody Affinity Chromatography

Monoclonal antibodies were generated for the isolation of specific antigens from Trichinella spiralis. Two monoclonal antibodies (7G6-2 and 10B6-1) of class IgG2b and IgG1 were selected according to their reactivities in an enzyme-linked immunosorbent assay and western blot. Clone 7G6-2 reacted with an antigen with molecular mass of approximately 60 kDa, and clone 10B6-1 bound to multiple antigens ranging from 49 to 62 kDa on western blot. Antibodies of each clone were purified partially from mouse ascites fluid by ammonium sulfate precipitation and were coupled to CNBr-activated Sepharose 4B. Antigens with molecular masses of 49 kDa and 57 kDa (P49/57), 52-62 kDa (P52/62), and 60 kDa (P60) were isolated from larval excretory-secretory products and crude worm extract with column 10B6-1 and column 7G6-2, respectively, in part by changing the pH of elution buffers. These antigens were mostly glycoproteins, strongly immunogenic, and specific to the parasite.

A soluble form of the interleukin 4 receptor in biological fluids

Murine biological fluids and murine cell culture supernatants were analyzed for the presence of soluble murine interleukin 4 receptor (sIL4R) with the use of two monoclonal antibodies directed against the receptor. Mouse urine, serum, ascitic fluid, and cell culture supernatants contained varying levels of immunoreactive protein. All of the immunoreactive protein possessed interleukin 4 (IL 4) binding activity. Following partial purification of ascitic fluid a protein was isolated that binds IL 4 with high affinity. This data is consistent with the fact that murine biological fluids contain a soluble version of the murine IL 4 receptor that arises via secretion of the soluble receptor and/or via shedding of the extracellular portion of the full-length receptor from the cell surface.