Expression of Ia-like antigens on cultured human malignant melanoma cell lines

Human malignant melanoma cell lines were found to bear Ia-like cell surface determinants demonstrable by hetero- or alloantisera and by direct identification of the characteristic bimolecular glycoprotein complex. Immunoprecipitation confirmed the presence of Ia determinants on the bimolecular complex. The quantity of Ia molecules determined by these methods and by absorption experiments was relatively constant for each cell line. Among different lines, however, the amount of Ia antigens ranged from a level equal to that expressed by B-cell lines to a small fraction of this amount. This variation in level of Ia contrasted with the more uniform amount of beta2-microglobulin detected on the cell surface. The Ia alloantigen specificity DRw2 was the most frequently encountered specificity. Ia determinants were also found on the surface of an epidermoid carcinoma line, but not on various other cell lines of normal or neoplastic origin.

Ia-bearing T lymphocytes in man. Their identification and role in the generation of allogeneic helper activity

The presence of Ia-like antigens was demonstrated on a small population (2-6%) of highly purified human circulating T lymphocytes by immunofluorescence with a rabbit anti-Ia serum raised against the isolated bimolecular Ia structure. The Ia+ T lymphocytes have no surface or intracellular immunoglobulins. The expansion of this Ia+ T-cell population was encountered in certain patients. Ia antigens were also found on T blasts grown in long-term cultures with conditioned medium generated by phytohemagglutinin-stimulated lymphocytes. In addition, leukemia blasts which stained for Ia antigens and formed E rosettes were identified in the peripheral blood of two leukemic patients. This evidence further supports the existence of Ia-bearing T cells in man. The Ia+ T-lymphocyte population was shown to contain cells responsible for the generation of allogeneic helper activity. Elimination of Ia+ lymphocytes from a purified T-cell population by the anti-Ia antiserum and complement abolished its ability to help an allogeneic B-cell preparation to generate plaque-forming cells against sheep erythrocytes in vitro in the presence of the antigen.

Mutagenicity of some commercially available nitro compounds for Salmonella typhimurium

Benzoyl chloride and 53 commercially available aromatic heterocyclic and aliphatic nitro compounds were tested for mutagenicity in Salmonella typhimurium TA98 and TA100. 34 of 53 nitro compounds (64%) were mutagenic, 4 in TA100 only, 15 in TA98 only, and 15 in both strains. 13 of the heterocyclic derivatives of pyridine, indole, indazole, quinoline, and benzimidazole were mutagenic. 21 of 34 mutagenic nitro compounds were bactericidal. Nitromethane was the only aliphatic tested and was not mutagenic. Benzoyl chloride, a human carcinogen, was mutagenic for TA98.

Inhibition of human erythropoietic colony formation in culture by treatment with Ia antisera

Incubation with Ia antiserum, followed by complement, markedly inhibited erythroid colonies arising from hematopoietic cells present in the nonadherent low density fractions of normal bone marrow. Both erythropoietin-dependent colonies and bursts were eliminated at dilutions of antiserum equivalent to, or greater than the dilutions required to abolish the granulocyte-macrophage colony formation. The inhibitory effect of the Ia antiserum was abolished by absorption with B but not T cells from lymphoid lines. Available evidence suggested that Ia determinants are expressed on the erythropoietin-sensitive progenitors of the erythroid series in precise analogy to their sequence of expression on the granulocyte lineage. In both lineages, as shown previously, the Ia determinants become undetectable during subsequent stages of differentiation.

A computer program for stepwise logistic regression using maximum likelihood estimation

A computer program has been written which performs a stepwise selection of variables for logistic regression using maximum likelihood estimation. The selection procedure is based on likelihood ratio tests for the coefficients. These tests are used in a forward selection and a backward elimination at each step. The use of the program is illustrated by several examples.

Patterns of expression of human "Ia-like" antigens during the terminal stages of B cell development

The "Ia-like" antigens characteristically present on the membrane of B lymphocytes were shown to be absent in most terminally differentiated Ig-producing plasma cells. This was most evident in analyses of myeloma plasma cells that uniformly lacked the Ia-antigens. Also, in B lymphoid cell lines, the lymphoblasts were uniformly Ia-positive but the plasma cells were negative. In contrast, however, the majority of plasma cells produced after pokeweed mitogen stimulation remained positive. Plasma cells in tonsil and in the tissue of peripheral blood of patients with Wladenström's macroglobulinemia were also sometimes Ia-positive although the majority were negative. Studies of membrane IgM and IgD indicated a similar loss in some instances. However, the SIg and Ia antigens were not invariably associated. These results lead to the conclusion that Ia-antigens are differentiation antigens for B cells and are usually lost by the end stage cells in this series.

Expression of Ia-like antigen molecules on human granulocytes during early phases of differentiation

Human B lymphocyte antigens analogous to the murine Ia determinants were found on myeloblasts and promyelocytes but not on more mature granulocytes. This was apparent by fluorescent staining with both human alloantisera and rabbit antisera to the isolated Ia-like proteins. The cells of patients with chronic myelocytic leukemia showed this difference especially clearly. Separation of the myeloblasts and promyelocytes by multistep density gradient fractionation produced a marked enrichment of the positive cells. The remaining cells from higher density fractions were more-mature neutrophils that were essentially negative. In acute myeloid leukemia, in which myeloid cells early in differentiation predominate, the vast majority of cells were strongly positive. Similar results were obtained with normal bone marrow cells. Here also, only the early forms of the myeloid series separated by gradient centrifugation had Ia antigens. Evidence was also obtained for the presence of Ia determinants on cells with the appearance of early erythroid precursors. Support for the presence of the Ia determinants on granulocyte-macrophage committed stem cells was provided by the inhibition of granulocyte colony formation in agar cultures following preincubation of normal bone marrow with antiserum and complement. Cross absorptions with purified preparations of immature cells provided evidence for the close similarity of the antigenic determinants on both myeloblasts and B cells. A 28,000-37,000-dalton bimolecular complex obtained from myeloblast membranes contained the Ia determinants and was similar to that obtained from peripheral blood B cell membranes.

Mutagenicity of hydroxamic acids for Salmonella typhimurium

P-Butoxyphenylacethydroxamic acid, benzohydroxamic acid, salicylhydroxamic acid, 2-naphthohydroxamic acid, indole-2-carbohydroxamic acid and benzoylaminoacethydroxamic acid were synthesized, and their mutagenicity for Salmonella typhimurium strains TA98 and TA100 were determined. Except for p-butoxyphenylacethydroxamic acid, all the hydroxamic acids were mutagenic for both strains. The mutagenicity progressed in the following order: 2-naphthohydroxamic acid greater than benzohydroxamic acid and salicylhydroxamic acid greater than benzoylaminoacethydroxamic acid and indole-2-carbohydroxamic acid. The starting materials for the synthesis of these acids including hydroxylamine were not in themselves mutagenic for TA98 and TA100. Thus, while the mutagenicity may require the hydroxamic acid as a whole, the acyl group may determine the mutagenic potency.

Effect of aminoethoxy analog of rhizobitoxine on ripening of pears

Ripening reactions in pears (Pyrus communis L.) were differentially affected by an aminoethoxy analog of rhizobitoxine (l-2-amino-4-[2-aminoethoxy]-trans-3-butenoic acid) (AAR). Ethylene production of both ;Anjou' and ;Bartlett' pears was inhibited by AAR. Decrease in firmness, increase in protein N and soluble pectin were delayed by AAR in ;Anjou' but not in ;Bartlett' pears. While loss in malic acid was retarded in ;Anjou' pears, rates of citric acid accumulation and malic acid reduction were not affected by AAR in ;Bartlett' pears.

Mutagenicity and antibacterial activity of hydroxamic acids

Hydroxamic acids demonstrated mutagenic and antibacterial activities. These activities appear to be dependent on the hydroxamic acid function and are probably due to the interaction with deoxyribonucleic acid.

Mutagenicity for Salmonella typhimurium of urine obtained from humans receiving nitrofurantoin

Urine samples from 12 humans receiving oral therapeutic doses of nitrofurantoin were mutagenic for Salmonella typhimurium strain TA 100 and nonmutagenic for strain TA 100-FR1. Mutagenic activity of the urine was not increased by treatment with beta-glucuronidase. Spot mutation assay of the chromatogram of urine revealed that the mutagenic activity of the urine was mainly due to unmetabolized nitrofurantoin.

Mutagenic activity of carcinogenic and noncarcinogenic nitrofurans and of urine of rats fed these compounds

The nitrofurans, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2), N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT), nitrofurantoin, 5-nitro-2-furoic acid, 5-nitro-2-furamidoxime, 5-nitrofurfurylidene diacetate and the urine of rats fed these compounds, were assayed for mutagenic activity in Salmonella typhimurium strains TA100 and TA100FR1. All the nitrofurans were mutagenic in the order: AF-2 and FANFT greater than nitrofurantoin greater than 5-nitro-2-furamidoxime greater than 5-nitrofurfurylidene diacetate greater than 5-nitro-2-furoic acid. Strain TA100 was more sensitive than TA100FR1 to the mutagenic influence of these nitrofurans. Only the urine of rats fed AF-2, FANFT and nitrofurantoin had mutagenic activity. Again, TA100 was more sensitive than TA100FR1. The mutagenicity of the urine was not increased by treatment with beta-glucuronidase. AF-2, 2-amino-4-(5-nitro-2-furyl)thiazole (deformylated product of FANFT) and nitrofurantoin were excreted in the urine of rats fed these compounds; whereas the other nitrofurans were not excreted.

A simple method for detection and analysis of carcinogenic nitrofuran compounds and their metabolites by combining chromatography and spot mutation tests

A simple, sensitive, and convenient method combining thin-layer chromatography and a spot test for mutagenicity of Salmonella typhimurium TA100 was utilized for the analysis of urine of rats fed N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide (FANFT), a potent experimental urinary bladder carcinogen. Three metabolites of FANFT were detected in urine, and one of these, accounting for 33% of the urinary metabolites of FANFT, was identified as 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT). ANFT was the only urinary metabolite that clearly demonstrated mutagenic activity, suggesting that ANFT may be a proximate vesical carcinogen of FANFT.

Studies with B-cell allo- and hetero-antisera: parallel reactivity and special properties

The expression of B-cell antigens on various cell populations was studied through the use of human alloantisera and with heteroantisera raised to preparations of the alloantigen bearing molecules isolated from B-cell lines. The allo-and hetero-antisera competed with each other in blocking experiments and gave closely parallel results, reacting with normal and leukemic B lymphocytes, monocytes, E-rosette-negative acute lymphatic leukemias, all acute and certain chronic myelogenous leukemias, and a minor population of cells in fetal spleen and liver. These highly immunogenic surface components appeared to comprise the dominant B- cell specific plasma membrane determinants. Neither type of antiserum reacted with any but a minor population of normal or pokeweed-mitogen-transformed T cells, fetal thymic lymphocytes, E-rosette-positive acute lymphatic leukemias, or Sezary-cell leukemia. Through the use of these antisera evidence was obtained that Fc-receptor-bearing Ig-negative lymphocytes were divisible into two groups according to the presence or absence of the B-cell antigens. Both hetero- and allo-antisera blocked binding of immune complexes or antibody-coated ox erythrocytes to Fc receptors on B cells. F(ab')2 fragments of the heteroantibodies strongly inhibited antibody-dependent cell-mediated killing.

Enhancing effect of allopurinol on the induction of bladder cancer in rats by n-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide

The effects of allopurinol on the induction of bladder cancer by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT), excretion of urinary tryptophan metabolites, hepatic nitroreductase activity, and the acid-soluble thiol content of liver and blood in weanling female Fischer rats were investigated. Four groups of rats were given normal diet or normal diet supplemented with 0.005% allopurinol, 0.188% FANFT, or 0.005% allopurinol-0.188% FANFT. Transitional cell carcinomas appeared in 3 of 30 rats (10%) at 15 weeks and in 7 of 44 rats (16%) at 20 weeks in the FANFT-treated group; the carcinomas appeared in 14 of 35 rats (40%) at 15 weeks and in 27 of 50 rats (54%) at 20 weeks in the FANFT-allopurinol-treated group. Growth rate was not affected by allopurinol and FANFT. Allopurinol alone caused no morphological change in the epithelial cells of the urinary bladder but decreased hepatic cytosol nitroreductase activity. FANFT alone had no effect on hepatic cytosol or microsomal nitroreductase activity but increased hepatic and blood acid-soluble thiol content. FANFT increased the urinary excretion of anthranilic acid glucuronide, kynurenine, acetylkynurenine, and 3-hydroxykynurenine and decreased indican and o-aminohippurate excretion. Allopurinol did not alter the effects of FANFT on the acid-soluble thiol content of liver and blood or the excretion of urinary tryptophan metabolites.

Identification of carcinogenic tannin isolated from Bracken fern (Pteridium aquilinum)

We attempted to isolate a carcinogenic substance from bracken fern (Pteridium aquilinum), a naturally occurring toxicant responsible for the production of chronic enzootic hematuria and urinary bladder cancer of cattle and carcinogenic for various target organs of several species. Hot methanol extracts of bracken fern were solubilized in water and extracted with chloroform followed by a mixture of n-butanol-butanone (1:1). That fraction was dried and triturated with ether-methanol (4:1), n-butanol, and finally absolute ethanol. The insoluble residue was dissolved in 10% aqueous methanol and passed through Dowex 1 OH-, Dowex 50 H+, or Dowex 1 OH- and then Dowex 50 H+ ion exchange resins. A condensed tannin, isolated from one ot the fractions, was identical to that isolated from bracken fern by the caffeine procedure used for the separation of tannins from other plant constituents. Three systems were used for bioassay; induction of bladder carcinoma by implantation of cholesterol pellets containing bracken fern fractions into the bladder lumens of mice; acute toxicity by ip injection of brachen fern fraction into mice; and growth inhibition of Escherichia coli. The following fractions induced significantly greater incidences of bladder carcinoma than did cholesterol pellets only: tannin, Dowex 50 H+, residue, n-butanol, and methanol. Tiliroside, a component of bracken fern fractions into the bladder lumens of mice; acute genic acid, and quercetin were not carcinogenic. Tannin was the most toxic (mean lethal dose: 0.16 mg/g) and carcinogenic. None of the carcinogenic fractions inhibited growth of E. coli.

Mutagenicity of nitrofurans, nitrothiophenes, nitropyrroles, nitroimidazole, aminothiophenes, and aminothiazoles in Salmonella typhimurium

Thirty-two heterocyclic compounds, including 24 nitroheterocycles, 7 aminoheterocycles and derivatives, and 1 thiophene lacking a nitro group, were tested for mutagenic activity in Salmonella typhimurium TA 98 and TA 100. All the nitroheterocycles (11 new), including nitrofurans, nitrothiophenes, nitropyrroles, and 1 nitroimidazole, were mutagenic in TA 100; 13 were also mutagenic in TA 98. 5-Nitro-2-furoic acid, a noncarcinogen, was mutagenic in TA 100. Seven carcinogenic nitroheterocycles were mutagenic in both strains. Seven aminoheterocycles (4 new), aminothiophenes and aminothiazole derivatives, and 1 thiophene without a nitro group were not mutagenic. Both TA 98 and TA 100 were uvrB and lacked the ability of excision repair of DNA. Among the 24 mutagenic nitroheterocycles, only 13 compounds exhibited bacterial killing effects, suggesting that more than 1 mechanism may be involved in the interaction of nitroheterocycles with bacterial DNA.

Studies of native plants in Taiwan for lectin content

The lectin content of some native plants in Taiwan was studied. The majority of the plants possessing lectin belonged to Leguminosae. Five lectins which are readily available were further studied for their hemagglutination titers, specificity, susceptibility to heat and proteolytic enzymes. The lectins of Ricinus communis had hemagglutination titer of 1:512 which was the highest among the five tested. All lectins were heat labile, destroyed by heating at 100 degrees C for 30 min, but resistant to trypsin and pepsin. The resistance was not due to the presence of any inhibitor in the crude extract, but possibly due to the special configuration of the lectin molecule or other unknow reasons. Among the five lectins only the lectin of Phaseolus vulgaris could not be inhibited by any of the carbohydrates tested. It seems that the lectin of Phaseolus vulgaris is nonspecific, or not specific for ABO blood group, or specific for other blood groups. The inhibiting activity of carbohydrates seems to be specific. The configuration of carbohydrates at carbon atom 2 and/or 4, the type of linkage (alpha or beta), or the carbon number where the linkage is formed seem to be important to the potency of carbohydrates to inhibit the activity of lectin.