Noncovalently bonded subunits of 22 and 28 kd are rapidly internalized by T cells reacted with anti-Leu-4 antibody

Using immunofluorescence analysis in a FACS or cytofluorograph, we monitored the density of four different human T cell surface molecules (Leu-1/OKT1, Leu-2/OKT5,8, Leu-3/OKT4, and Leu-4/OKT3) at different intervals of incubation at 37 degrees C with monoclonal antibodies that react with these structures. Leu-1 and Leu-2 are probable human homologues of the murine Lyt-1 and Lyt-2,3 antigens, respectively. Leu-3 is a 55 kd antigen that is restricted to Leu-2- (helper) T cells. Leu-4 is expressed by all peripheral T cells and has at least two components of 22 and 28 kd that have an undefined structural relationship. The ultimate degree of modulation of each antigen varied considerably. Modulation of Leu-4 was particularly striking, because this antigen disappeared completely from the cell membrane within 7 hr of culture with saturating concentrations of alpha Leu-4. After modulation of surface 125I-labeled T cells, Leu-4 was found in the detergent-solubilized cell lysate, but not in the cellfree supernatant, indicating that it was internalized. Our results also indicated that the internalized antigen-antibody complex existed in at least two forms: a) as an antigen-antibody complex having only the lower m.w. (22 kd) component bound to antibody, or b) as free antigen having the 28 kd chain in noncovalent association with the 22 kd moiety. These studies indicate that the Leu-4 structure is composed of at least two distinct chains that are noncovalently associated. The rapid modulation and structural properties of the Leu-4 complex are discussed in the context of its possible functions in T cell immunity.

Noncovalently bonded subunits of 22 and 28 kd are rapidly internalized by T cells reacted with anti-Leu-4 antibody

Using immunofluorescence analysis in a FACS or cytofluorograph, we monitored the density of four different human T cell surface molecules (Leu-1/OKT1, Leu-2/OKT5,8, Leu-3/OKT4, and Leu-4/OKT3) at different intervals of incubation at 37 degrees C with monoclonal antibodies that react with these structures. Leu-1 and Leu-2 are probable human homologues of the murine Lyt-1 and Lyt-2,3 antigens, respectively. Leu-3 is a 55 kd antigen that is restricted to Leu-2- (helper) T cells. Leu-4 is expressed by all peripheral T cells and has at least two components of 22 and 28 kd that have an undefined structural relationship. The ultimate degree of modulation of each antigen varied considerably. Modulation of Leu-4 was particularly striking, because this antigen disappeared completely from the cell membrane within 7 hr of culture with saturating concentrations of alpha Leu-4. After modulation of surface 125I-labeled T cells, Leu-4 was found in the detergent-solubilized cell lysate, but not in the cellfree supernatant, indicating that it was internalized. Our results also indicated that the internalized antigen-antibody complex existed in at least two forms: a) as an antigen-antibody complex having only the lower m.w. (22 kd) component bound to antibody, or b) as free antigen having the 28 kd chain in noncovalent association with the 22 kd moiety. These studies indicate that the Leu-4 structure is composed of at least two distinct chains that are noncovalently associated. The rapid modulation and structural properties of the Leu-4 complex are discussed in the context of its possible functions in T cell immunity.

A new human B-lymphocyte surface antigen (BL 2) detectable by a hybridoma monoclonal antibody: distribution on benign and malignant lymphoid cells

A hybridoma-derived monoclonal antibody, produced by immunization with the Burkitt's tumor-derived B-lymphoblastoid cell line, B35M, was previously shown to detect a 68,000 dalton surface membrane protein, BL2, on the surface of peripheral blood B cells, which is absent from thymocytes, T cells, and granulocytes. In this study, we investigated the expression and distribution of BL2 on benign and malignant human lymphoid cells. Indirect immunofluorescent assay with this monoclonal antibody demonstrated that BL2 is expressed by cells within the fetal liver and by a variable proportion of lymph node, tonsil, and spleen B cells, but not by T cells. The neoplastic cells isolated from 18 T-cell malignancies were BL2- . BL2 was was heterogeneously expressed by a variable proportion of the malignant cells in 29/32 cases of B-chronic lymphocytic leukemia and 33/38 cases of B-cell lymphomas, but appeared to be lost in the terminal stages of B-cell differentiation, as myeloma plasma cells were BL2- . BL2 expression was not limited to B cells of a particular surface immunoglobulin isotype. Immunofluorescent staining for BL2 in cryostat tissue sections demonstrated that the majority, but not all, germinal center and interfollicular Ia+ (non-T) cells are BL2+. These findings suggest that BL2 is a B-cell lineage-specific differentiation marker that may be useful in the study of B-cell ontogeny and in defining subgroups of the B-cell malignancies.

Effect of phenobarbital on the carcinogenesis of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide in rats

Male Fischer rats were fed a N-[4-(5-nitro-2-furyl]-2-thiazolyl]formamide (FANFT) diet for 6 weeks followed by a phenobarbital (PB) diet for an additional 86 weeks. PB significantly increased the incidence of bladder tumors, but not the incidence of hepatic foci and areas of cellular alterations caused by FANFT. The results suggest that PB may be a weak promoter for bladder carcinogenesis, and that FANFT may not be an initiator for hepatocarcinogenesis.

Synthesis of the 3'-half molecule of yeast alanine tRNA

This paper deals with the synthesis of the 3'-half molecule of yeast alanine transfer RNA (tRNAAlay) by ligation with T4 RNA ligase of three component oligonucleotide fragments corresponding to nucleotides 36-45(I), 46-57(II) and 58-76(III) in succession extending from the 3'-end to the 5'-end. First, in a ratio of acceptor to donor at 1.5 to 1, we adopted a method of three successive reactions, namely, the 5'-phosphorylation of the nonadecamer (III), ligation with the dodecamer (II) and the 5'-phosphorylation of the ligation product formed; with one isolation step and obtained the 5'-phosphorylated 31mer(46-76) (IV) in an overall yield of 70%. Then the 31mer(IV) as a donor was ligated with 3 times of decamer (I) to form the 41mer(36-76) (V), the 3'-half molecule of tRNAAlay. The yield was 67%. After 5'-phosphorylation, (V) was ligated with the natural 5'-half molecule to form the semi-synthetic tRNAAlay, which was biologically active, i.e. accepting and transferring (3H)-alanine into proteins.

Conversion of Congo red and 2-azoxyfluorene to mutagens following in vitro reduction by whole-cell rat cecal bacteria

Congo red, an azo dye derived from benzidine, and 2-azoxyfluorene, a derivative of 2-aminofluorene, were reduced during overnight incubation with a suspension of rat intestinal bacteria. High performance liquid chromatography and ultraviolet spectral analysis verified the presence of benzidine in extracts of the Congo red incubations and 2-aminofluorene in extracts of the 2-azoxyfluorene incubations. Extracts of the Congo red incubations were mutagenic toward Salmonella typhimurium TA1538 in the presence of a post-mitochondrial activating system, but Congo red was not mutagenic without this reductive pretreatment. Thus, the utility of the Ames test in screening for potential mutagens may be expanded by a reductive pretreatment utilizing cecal bacteria.

Production and regulation of interleukin-2 in human lymphoblastic leukemias studied with T-cell monoclonal antibodies

Human leukemias are illnesses of hemopoietic stem cells that go through processes of self-replication and partial differentiation under the control of as yet largely unknown growth and differentiation factors. IL-2 is a powerful factor controlling proliferation of normal T cells. We report that acute lymphoblastic leukemias of T and non-B, non-T phenotypes produce a growth factor after mitogen stimulation. This factor is able to support the proliferation of human and murine IL-2-dependent cytotoxic cells, has a mol wt of 26,000 daltons by gel filtration, an isoelectric point of 6.6, and its biologic activity is inhibited by an anti IL-2 monoclonal antibody. This factor is, therefore, by all parameters studied very similar to IL-2 produced by normal lymphocytes. A recently developed monoclonal antibody, Pan T2, binds to normal T cells, renders T cells responsive to IL-2, and induces the release of IL-2, which in turn provides the second signal for T-cell proliferation. Mononuclear cells from acute lymphoblastic leukemia do not respond to the addition of this monoclonal antibody unless cocultured with irradiated Daudi cells. Since normal T cells do not require Daudi to produce IL-2 and since Daudi cells do not produce IL-2 under any conditions, we conclude that the cell responsible for IL-2 production in acute lymphatic leukemia is a leukemic T cell with an altered mechanism of IL-2 production at the level of the Pan T2 binding site.

Prostaglandin H synthase-mediated reaction of carcinogenic arylamines with tRNA and homopolyribonucleotides

Prostaglandin H synthase mediates the reaction of an extensive series of carcinogenic arylamines with tRNA. Structure-activity relationships suggest that benzidine is especially reactive due to extended conjugation between the 4,4'-diamino groups. In trapping experiments with homopolyribonucleotides, benzidine reacts with polyguanylic acid but 4-aminobiphenyl reacts with polycytidylic acid. The nitrenium ion of 4-aminobiphenyl (formed by N,O-acyltransferase activation of N-hydroxy-4-acetylaminobiphenyl) reacts primarily with polyguanylic acid and to a lesser extent with polyadenylic acid. The results suggest that arylamine activation by prostaglandin H synthase does not involve nitrenium ion formation.

Endoscopic examination of the upper gastrointestinal tract in infancy

Forty endoscopic examinations of the upper gastrointestinal tract were performed in 38 infants with an age range from 2 days to 12 months. The main indications were upper gastrointestinal bleeding, chronic intractable vomiting, and small intestinal biopsy. Duodenal ulcer, hemorrhagic gastritis, and gastric erosions were the most common causes of upper gastrointestinal bleeding in infancy. An acute viral infection with fever, aspirin ingestion, and diarrhea frequently preceded gastrointestinal bleeding from duodenal ulcer and gastric erosion. Four of the 27 bleeding patients demonstrated no abnormality endoscopically.

Induction of IgG production in a human monoclonal B lymphoblastoid cell line by a B cell-specific monoclonal antibody

IgG production was induced in a human B blastoid cell line, CESS, by stimulation with a human B cell-specific monoclonal antibody (IIIA4). The number of IgG-producing cells reached its maximal level within 48 hr after incubation with IIIA4. IgG-producing cells induced by an optimal concentration of the antibody was about one-half as many as those induced with TRF, but higher concentrations of the antibody were rather inhibitory. Simultaneous addition of an optimal concentration of the antibody with TRF partially inhibited TRF-induced IgG production in CESS cells, but higher concentrations of the antibody did not block TRF-induced IgG production. TRF activity was completely absorbed with IIIA4-coated CESS cells as well as nontreated CESS cells. These results suggested that the membrane antigen recognized by IIIA4 was not the acceptor molecule for TRF. IIIA4 did not show any inhibitory effect on PWM-induced proliferation of normal B cells, but completely inhibited PWM-induced Ig production of normal B cells.

Induction of IgG production in a human monoclonal B lymphoblastoid cell line by a B cell-specific monoclonal antibody

IgG production was induced in a human B blastoid cell line, CESS, by stimulation with a human B cell-specific monoclonal antibody (IIIA4). The number of IgG-producing cells reached its maximal level within 48 hr after incubation with IIIA4. IgG-producing cells induced by an optimal concentration of the antibody was about one-half as many as those induced with TRF, but higher concentrations of the antibody were rather inhibitory. Simultaneous addition of an optimal concentration of the antibody with TRF partially inhibited TRF-induced IgG production in CESS cells, but higher concentrations of the antibody did not block TRF-induced IgG production. TRF activity was completely absorbed with IIIA4-coated CESS cells as well as nontreated CESS cells. These results suggested that the membrane antigen recognized by IIIA4 was not the acceptor molecule for TRF. IIIA4 did not show any inhibitory effect on PWM-induced proliferation of normal B cells, but completely inhibited PWM-induced Ig production of normal B cells.

Inhibition of 4-nitroquinoline 1-oxide induced unscheduled DNA synthesis in primary cultures of rat urothelial cells by dicumarol and pyrophosphate

Primary cultures of rat urothelial cells were exposed to hydroxyurea, [3H]thymidine, and 4-nitroquinoline 1-oxide (NQO) or N-hydroxy-4-aminoquinoline 1-oxide (HAQO) in a serum-free media for 2 h; unscheduled DNA synthesis (UDS) was measured by autoradiography. Both NQO and HAQO produced unscheduled DNA synthesis. Dicumarol, an inhibitor of NQO nitroreductase, inhibited the activity of NQO and, to a lesser extent, HAQO. Pyrophosphate, an inhibitor of seryl-AMP synthetase, inhibited the activity of both compounds. Neither dicumarol nor pyrophosphate, under similar experimental conditions, inhibited the activity of N-hydroxy-N-2-acetylaminofluorene (N-OH-AAF). These results support the idea that nitro-reductase and seryl-AMP synthetase may be involved in the activation of NQO.

Induction of unscheduled DNA synthesis in primary culture of dog, rat, and mouse urothelial cells by arylamine and nitrofuran derivatives

The induction of unscheduled DNA synthesis in primary cultures of urothelial cells from rats, mice, and dogs by nitrofurans and arylamines and their derivatives was examined. Electron microscopy of the culture from rat cells showed the characteristics of epithelial cells. The cultured cells were exposed to the test chemicals in a serum-free medium containing 10 mM hydroxyurea and [3H]thymidine for 24 hr, and unscheduled DNA synthesis was determined by autoradiography. N-Hydroxy-2-aminofluorene, N-hydroxy-2-acetylaminofluorene, N-hydroxy-4-amino-biphenyl, and N-hydroxy-4-acetylaminobiphenyl were active in inducing unscheduled DNA synthesis in the urothelial cells of rats, mice, and dogs. 2-Aminofluorene, N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide, and 2-amino-4-(5-nitro-2-furyl)thiazole were active only in dog cells. 2-Acetylaminofluorene and 4-aminobiphenyl were not active. These results demonstrate that urothelial cells contain enzymes that can selectively activate bladder carcinogens and their metabolites.

Purification of human interleukin 2 to apparent homogeneity and its molecular heterogeneity

Interleukin 2 (IL-2), produced with and without co-stimulation by the Burkitt's lymphoma line Daudi, was purified 37,000-fold to apparent homogeneity from lymphocyte conditioned medium by (NH4)2SO4 precipitation, DEAE-cellulose ion-exchange chromatography, gel filtration, and chromatography on blue agarose and on Procion-red agarose. The purified IL-2 showed a 10(6) U/mg protein sp act. IL-2 produced in the absence of Daudi cells had a mol wt of 26,000 as measured by gel filtration and an isoelectric point of 6.7. This IL-2 showed a 16,000 and 17,000 mol wt in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). IL-2, produced in the presence of Daudi cells (10(6)/ml), showed a mol wt of approximately 14,000, as measured by both gel filtration and SDS-PAGE, and an isoelectric point of 8.1. The purified IL-2 lacked detectable interferon (alpha and gamma), granulocyte-macrophage colony-stimulating factor, B cell growth factor, T cell-replacing factor, and thymocyte-differentiating activity and was free of any contaminating proteins as judged by silver staining in SDS-PAGE. All three molecular forms of IL-2 were biologically active at concentrations of 10(-11) - 10(-10) M, supporting the growth of human and murine cytotoxic T cell lines.

Hepatitis B e antigen and antibody in asymptomatic Chinese with hepatitis B surface antigenemia in Taiwan

Two hundred and twenty two asymptomatic carriers of hepatis B surface antigen (HBsAg) with age between 4 months and 68 years, 172 healthy persons with antibody to HBsAg (anti-HBs) and 85 healthy persons seronegative for both HBsAg and anti-HBs were studied by double immunodiffusion for the evaluation of the meaning of hepatitis B e antigen (HBeAg) and its antibody (anti-HBe). In 222 asymptomatic carriers, HBeAg was detected in 32.4% and anti-HBe in 31.5%. The geometric titer of HBsAg was 1:2159 in the HBeAg positive and 1:149 in the anti-HBe positive persons. Frequencies of HBeAg and anti-HBe in asymptomatic carriers of HBsAg correlated closely with age. The highest frequency of HBeAg was found in the first decade in 64% decreasing steadily to 20.8% in the fourth and then suddenly down to 4.1% in the fifth decade. A reverse trend was observed in anti-HBe frequency. From our analysis, it is likely that the high frequency of HBeAg in serum of Chinese, especially in females of fertile age, might be an important contributing factor for the high rates of hepatitis B virus (HBV) infection and HBsAg carrier in Taiwan. The presence of HBeAg/anti-HBe system is not only a market of infectivity and prognosis but also a chronologic marker of HBV infection.

The expression of surface antigen Leu 1 by ocular adnexal lymphoid neoplasms

Leu 1 is a surface membrane antigen expressed by benign systemic T cells, most cases of B-cell-derived chronic lymphocytic leukemia, and approximately one half of the systemic B-cell lymphomas. Benign systemic B cells are Leu 1-. Our studies showed that the percentage of Leu 1+ cells was essentially the same as the percentage of OKT3+E+ (T) cells in six ocular adnexal pseudolymphomas, strongly suggesting that the benign B cells in these lesions were similarly Leu 1-. These studies also showed that malignant B cells in six of 15 (40%) ocular B-cell lymphomas were Leu 1+. Thus, the expression of Leu 1 by some malignant ocular adnexal B cells but not by benign ocular adnexal B cells appears to be analogous to the situation for lymph nodal and other systemic B cells. Although the explanation for the existence of this shared determinant is unknown, Leu 1 expression may possess clinical and diagnostic significance as a marker of neoplastic B cells.

Senescence of Rice Leaves : VII. PROLINE ACCUMULATION IN SENESCING EXCISED LEAVES

Proline content increased greatly in detached rice (Oryza sativa cv. Taichung Native 1) leaves during senescence. There was a slight but significant increase in proline level after one day of incubation, and, subsequently, proline accumulated relatively rapidly. By 4 days after excision, the level of proline had increased 30- to 50-fold, which is similar to the level seen in the water-stressed detached rice leaves. It is unlikely that the proline accumulation in detached leaves is to be derived solely from protein hydrolysis, since the addition of l-glutamic acid increased the proline level during senescence. The proline analog, 3,4-dehydroproline, did not affect the level of proline during senescence. It seems that accumulation of proline may, at least in part, result from an increased rate of synthesis, possibly due to a disruption of the normal feedback inhibition of proline synthesis. Potassium cyanide and 2,4-dinitrophenol strongly inhibited proline accumulation, indicating that some energy compound(s) may participate in proline accumulation during senescence of excised rice leaves.