The epitope specificity and tissue reactivity of four murine monoclonal anti-CD22 antibodies

The CD22 antigen is expressed on the surface of normal human B cells and some neoplastic B cell lines and tumors. Previous cross-blocking studies using a panel of monoclonal anti-CD22 antibodies have defined four epitope groups, termed A-D. In the present studies, we have further dissected the epitopes recognized by four monoclonal anti-CD22 antibodies using immunoprecipitation and cross-blocking techniques, immunofluorescence analyses with a variety of cell lines, and immunoperoxidase analyses of 36 normal human tissues. Two of the antibodies, HD6 and RFB4, have been described previously, and two, UV22-1 and UV22-2, are described in this report. Our studies indicate that the four monoclonal antibodies show unexpected complexities in their reactivity with CD22+ and CD22- cells and their reactivity with solubilized CD22 molecules. The four antibodies, which recognize epitopes defined previously as CD22-A and CD22-B, further subdivide these epitope clusters into four determinants, A1, A2, B1, and B2. Furthermore, only two of the antibodies, RFB4 and UV22-2, are B cell-specific. In summary, our data indicate that RFB4 and UV22-2 would be the antibodies of choice for constructing immunotoxins to treat B cell tumors.

Evaluation of four CD22 antibodies as ricin A chain-containing immunotoxins for the in vivo therapy of human B-cell leukemias and lymphomas

Ricin A chain-containing immunotoxins (IT-As) specific for the human B-cell antigen, CD22, were prepared from 4 monoclonal antibodies (MAbs) or their Fab' fragments: RFB4, HD6, UV22-I and UV22-2. The ITs were tested for their ability to kill cells from the Burkitt lymphoma line, Daudi, the pre-B-cell leukemia line, NALM-6, and the myeloma cell line, ARH-77. Daudi expresses high levels of CD22, whereas NALM-6 and ARH-77 express low levels of CD22. The IgG-RFB4-A was highly toxic to all 3 cell lines; it killed 50% of the Daudi cells at a concentration of 1.2 x 10(-12) M and 50% of NALM-6 and ARH-77 cells at concentrations of 1.5 to 2.1 x 10(-11) M. IgG-RFB4-A was 10-30 times more toxic to Daudi cells than were the IgG-As constructed from the other 3 CD22 MAbs and 10 times more toxic than ricin itself. IT-As constructed from the Fab' fragments of the 4 CD22 antibodies were 2 to 5 times less toxic to Daudi cells than their IgG-A counterparts. Fab'-RFB4-A was twice as toxic to Daudi cells as ricin, whereas the other Fab'-As were about 7 times less toxic than ricin. Scatchard analyses of the binding of the radio-iodinated antibodies to Daudi cells showed that the intact RFB4 antibody bound 3-10 times more strongly than the other antibodies, whereas the Fab'-RFB4 bound 1.2 to 3.5 times more strongly than the Fab' fragments prepared from the other antibodies. Thus, the potent cytotoxic activity of the RFB4-As appears to derive, in part, from their superior binding affinity. Prior studies have shown that UV22-I and HD6 cross-react with certain normal human tissues lacking cells of B-cell lineage, whereas UV22-2 and RFB4 are B-cell-specific. This fact, together with its superior potency as an IT-A, suggests that RFB4 is the antibody of choice for preparing Fab'-As or IgG-As for in vivo therapy of human B-cell leukemias and lymphomas.

Sex differences in ferric nitrilotriacetate-induced lipid peroxidation and nephrotoxicity in mice

Since male A/J mice are much more susceptible to both acute and subacute nephrotoxicity and the carcinogenic effect of ferric nitrilotriacetate than female mice, sex differences in the lipid peroxidation level after ferric nitrilotriacetate use were examined. The effects of orchiectomy and testosterone were also investigated. Male and female A/J mice were given a single intraperitoneal injection of ferric nitrilotriacetate (3 mg of iron/kg of body weight) and then thiobarbituric acid reactivity was determined in the liver and the kidney. Only male mice showed high thiobarbituric acid reactivity after 30 min, with the kidney showing higher activity than the liver. Castrated male mice showed a reduction in thiobarbituric acid reactivity, whereas testosterone-pretreated castrated male or testosterone-pretreated female mice showed increased thiobarbituric acid reactivity. In addition, daily intraperitoneal injections of ferric nitrilotriacetate resulted in the death of all normal male mice within 6 days, whereas all female and castrated male mice survived 3 months of treatment. Thus, male and female mice showed differences in ferric nitrilotriacetate-induced toxicity as reflected in the degree of lipid peroxidation and mortality.

Effect of dietary vitamin E on ferric nitrilotriacetate-induced nephrotoxicity in rats

The effect of dietary vitamin E on renal tissue damage and lipid peroxidation was investigated following treatment with ferric nitrilotriacetate (Fe-NTA) in rats. Almost 100% renal proximal tubular necrosis was observed in the vitamin E-deficient rats following Fe-NTA treatment (5 mgFe/kg body wt, ip) as early as 12 hr. In the vitamin E-supplemented rats, no injury was observed in the proximal convoluted (cortical) tubules, although some injury was seen in the medullary outer stripe (mostly pars recta of the proximal tubules) 24 hr after Fe-NTA treatment. The tissue lipid peroxidation was dose-dependently increased 1 hr after a single ip injection of Fe-NTA (1 to 10 mg Fe/kg body wt). Vitamin E-deficient animals had an increased tissue content of thiobarbituric acid-reactive substance following Fe-NTA treatment, whereas vitamin E-supplemented animals showed suppressed lipid peroxidation. This study indicates that vitamin E provides some protection against the nephrotoxicity and associated lipid peroxidation induced by Fe-NTA.

Nephrotoxicity and its prevention by vitamin E in ferric nitrilotriacetate-promoted lipid peroxidation

Iron and aluminum complexes of nitrilotriacetic acid cause severe nephrotoxicity in Wistar rats. In addition, a high incidence of renal cell carcinoma is seen in ferric nitrilotriacetate-treated animals. The present study was performed to see if lipid peroxidation is involved in ferric nitrilotriacetate toxicity. Ferric nitrilotriacetate had more bleomycin-detectable 'free' iron than any ferric salt, while iron complexed with desferrioxamine or ferric chondroitin sulfate had none. The toxicity of ferric nitrilotriacetate in vivo was more pronounced in vitamin E-deficient rats. A thiobarbituric acid-reactive substance was present in the kidneys of vitamin E-deficient rats in amounts markedly elevated compared to vitamin E-sufficient, or vitamin E-supplemented rats. Non-complexed nitrilotriacetate or aluminum nitrilotriacetate did not produce any thiobarbituric acid-reactive substance in vitamin E-sufficient rats died by the 58th day of administration. We suggest that the iron-stimulated production of free radicals leading to lipid peroxidation is the major cause of ferric nitrilotriacetate-mediated renal toxicity. Vitamin E, a known scavenger of free radicals, is effective in protecting against this iron-induced toxicity.

Inhibitory, opsonic and cytotoxic activities of monoclonal antibodies against asexual erythrocytic stages of Plasmodium falciparum

A range of monoclonal antibodies specific for Plasmodium falciparum were tested in vitro for their abilities to inhibit the multiplication of a partially synchronized culture of P. falciparum, to augment the phagocytosis of the parasites by macrophages, and to enhance the killing of parasites by peritoneal cells depleted of adherent cells. Seven of 17 monoclonal antibodies, ranging from culture supernatant fluid and ascitic fluid to purified IgG, showed dose- and time-dependent inhibition of parasite growth in vitro. At a concentration of 0.6 mg/ml, the inhibitory capacity of these monoclonal IgGs was above 94% over a 3-day culture period, much higher than that of the relevant polyclonal IgG. Four of 6 monoclonal antibodies tested augmented the phagocytosis of the parasites by macrophages, which occurred as a result of opsonization of the parasites. Four of 7 monoclonal antibodies examined showed cytotoxic activity on malaria parasites. Peritoneal cells depleted of adherent cells were capable of killing the parasites in the presence of monoclonal antibodies. These results indicate that there may be 'monofunction', 'bifunction', and 'multifunction' types of monoclonal antibodies against P. falciparum. The putative protective antigen of malaria parasites purified by 'multifunctional monoclonal antibody' affinity chromatography may have potential interest as a vaccine against the parasite or as an immunodiagnostic reagent for human malaria.

Subacute nephrotoxicity and induction of renal cell carcinoma in mice treated with ferric nitrilotriacetate

We investigated the induction of renal tumors by the ferric complex of nitrilotriacetic acid (Fe-NTA) in male and female A/J mice. Fifty-three male and 21 female mice received i.p. injections of Fe-NTA, 1.8 to 2.7 mg of iron/kg of body weight/day, 6 days a wk for 12 wk, at the longest. Ten male and ten female mice received nitrilotriacetic acid (NTA) i.p. at the dose equivalent to the NTA portion of Fe-NTA for the same period of time. Twenty male and 20 female mice left untreated served as the controls. Twenty-eight of the 53 Fe-NTA-treated male mice died within 14 days of the treatment. Renal proximal tubular cell necrosis was the major autopsy finding in these mice. On the other hand, all the Fe-NTA-treated female mice and NTA-treated male and female mice survived the 12 wk of treatment. Renal tubular cell carcinoma had developed in 15 of the 25 male mice and in one of the 21 female mice by the 420th day after the start of the experiment. The NTA-treated and control mice did not develop any tumors. In conclusion there is no species specificity in rats or mice in the induction of the renal carcinoma by Fe-NTA, but male mice are far more susceptible to both the acute or subacute toxicity and carcinogenic effect of Fe-NTA than are female mice.

A new subtype of a natural viral inhibitor (CVI) that is stable in the gastrointestinal tract

A virus inhibitor found in gastric secretions and in extracts from gastrointestinal tissues is described. The inhibitor shares a number of characteristics with the recently described contact-blocking virus inhibitor (CVI), which is produced by unstimulated cells in culture, and occurs naturally in some body fluids. The new inhibitor, which we have designated gastrointestinal-CVI (GI-CVI) is similar to the originally described CVI in its resistance to denaturation by acid and alkali, stability at 100 degrees C, and broad antiviral action. GI-CVI can be distinguished from the previously described material by its resistance to proteolytic inactivation and enhanced heat stability, however. This new virus inhibitor has been found in significant titers in gastrointestinal secretions and tissue extracts from three mammalian species.

Synthesis of nitrosomethylisoamylamine from isoamylamine and sodium nitrite by fungi

Nitrosomethylisoamylamine (NMIA), a carcinogenic N-nitroso compound was synthesized from isoamylamine (IAA) in a glucose-ammonium nitrate medium after several days' incubation with fungi and subsequent nitrosation with sodium nitrate. The nitrosamine was not produced by control reactions which lacked either IAA or fungi. The yield of NMIA varied with the length of incubation after inoculation with the fungi, and with the concentrations of IAA and NaNO2, the duration of nitrosation, the pH of the medium and the species of the fungi. The optimum conditions for the formation of the nitrosamine are reported.

Nephrotoxicity and renal cell carcinoma after use of iron- and aluminum-nitrilotriacetate complexes in rats

Wistar male rats were tested for nephrotoxicity and carcinogenicity after administration of ferric nitrilotriacetate [(NTA) CAS: 139-13-9] (Fe-NTA) [No. of rats (n) = 24] and Al-NTA (n = 24). The control rats were given AlCl3 (n = 10), NTA (n = 10), and saline (n = 10). Sublethal doses of Fe-NTA [5-7 mg Fe/kg (body wt)] and Al-NTA [1.5-2.0 mg Al/kg (body wt)] were chosen and injected ip for 3 months. AlCl3 and NTA were given in equivalent doses and saline was given in equivalent volumes. All the rats given Fe-NTA or Al-NTA had a depressed weight gain, polyuria, and glucosuria from the 1st week. Histologically, acute tubular necrosis and regenerating epithelial cells were observed. Regenerative atypical epithelial cells in the renal cortex were seen at the termination of Fe-NTA or Al-NTA administration. Control rats had no remarkable changes. After 1 year, primary renal cell carcinoma and metastases to liver, lung, and peritoneum were observed only in Fe-NTA-treated rats (14 of 18 surviving rats). On the contrary, there were no tumors in Al-NTA-treated rats (none of 12 surviving rats). The results suggest that nephrotoxicity and renal cell carcinoma are two independent phenomena from Al-NTA treatment and that a long-term sublethal dose of Al-NTA is not related to renal carcinogenicity.

Synthesis of methylisoamylnitrosamine from isoamylamine by fungi (Fusarium moniliforme)

Methylisoamylnitrosamine, a carcinogenic N-nitroso compound, has been formed in glucose ammonium nitrate medium containing 150 mg of isoamylamine (a primary amine) inoculated with a common fungus (Fusarium moniliforme Sheldon), to which 400 mg NaNO2 are added after incubation for 7-8 days at 28 degrees C. No such compound has been found in control samples without fungi or isoamylamine. This paper reports a method of experimental synthesis of the nitrosamine by F. moniliforme strains 82-01 and 83-01, using isoamylamine and NaNO2, as well as the analysis of the compound by GC/MS and GC/TEA.

A new N-nitroso compound, N-2-methylpropyl-N-1-methylacetonyl-nitrosamine, in moldy millet and wheat flour

A new N-nitroso compound, N-2-methylpropyl-N-1-methylacetonyl-nitrosamine (MAMPNA), was found in millet and wheat flour inoculated with Fusarium moniliforme Sheldon, a common species of fungi occurring in foods in Linxian County, after 8-day incubation and an addition of a small amount of NaNO2. The compound has been identified by GC-MS and confirmed by synthesized MAMPNA. The present paper reports the isolation and detection of MAMPNA in moldy foods, and discusses the role of the fungus in processes of nitrosamine formation and possible biosynthetic approach of the new compound.

Influence of pN2 and pD2 on HD formation by various nitrogenases

Formation of HD from D2 has been demonstrated with nitrogenase preparations from Azotobacter vinelandii, Clostridium pasteurianum, Klebsiella pneumoniae, and Azospirillum sp. We conclude that the formation of HD from D2 is a general property of nitrogenases. However, the nitrogenases differ in their Ki values for D2 (N2 fixation) and in their rates of catalyzing HD formation; among the nitrogenases tested, C. pasteurianum nitrogenase had the lowest activity for formation of HD. When contaminating N2 was removed from the atmospheres above reaction mixtures, less than 1% of the total electron flux in the system was directed to HD formation; hence, we doubt that N2-independent HD formation is significant. A working hypothesis is suggested that operates without invoking an N2-independent reaction for forming HD.