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Distinct target cells and effects of 1 alpha,25-dihydroxyvitamin D3 and glucocorticoids in the rat thymus gland.

Thymocytes are known to possess receptors for glucocorticoids (GC) as well as for alpha, 25-dihydroxyvitamin D3 [1,25-(OH)2D3]. We have now investigated the distribution of the receptors for GC and 1,25-(OH)2D3 in rat thymocytes and compared the effects of the two steroid hormones on short term primary cultures of these cells. We report that in thymic cells, as in other tissues, 1,25-(OH)2D3 and GC bind specifically to distinct receptor molecules which exhibit sedimentation coefficients of 3.3S and 3.7S, respectively. Furthermore, the thymocytes that express the 1,25-(OH)2D3 receptor belong to a different and distinct subpopulation than the cells that express the glucocorticoid receptor. Specifically, by separating the thymocytes into two subsets by means of agglutination with the lectin peanut agglutinin (PNA), we have determined that the 1,25-(OH)2D3 receptor-positive cells belong to the PNA-negative medullary mature subset, whereas the GC receptor-positive cells belong to the PNA-positive cortical immature subset of thymocytes. Finally, we have compared the effects of the two steroid hormones on primary cultures of each of the two subsets as well as on unseparated thymocytes and found that GC act on PNA-positive cells to induce cell lysis; this leads to an enrichment in 1,25-(OH)2D3 receptor-positive thymocytes, as indicated by an apparent increase (6-fold) in the 1,25-(OH)2D3 binding in the cells surviving at the end of the culture. In contrast, we found that 1,25-(OH)2D3 acts on the PNA-negative cells to decrease the rate of cell lysis. These data indicates that the target cells for GC and 1,25-(OH)2D3 in the thymus are distinct and that these two hormones exert a different regulatory influence on the gland.

Animals↗

Amino acid sequence and some properties of lectin-D from the roots of pokeweed (Phytolacca americana).

Two pokeweed lectins, designated PL-D1 and PL-D2, have been isolated from the roots of pokeweed (Phytolacca americana) using chitin affinity column chromatography followed by gel filtration on a Sephacryl S-200 column and fast protein liquid chromatography on a Mono-Q column, and their amino acid sequences have been analyzed. PL-D1 consists of 84 amino acid residues and has a molecular mass of 9317, while PL-D2 has an identical sequence with PL-D1 except lack of the C-terminal Leu-Thr. PL-D is composed of two chitin-binding domains, A and B, with 50% homology with each other. Both PL-Ds did not agglutinate native rabbit erythrocytes, but showed about 0.1% of the agglutinating activity of wheat germ agglutinin toward trypsin-treated erythrocytes. In the presence of beta (1-->4) linked oligomers of N-acetyl-D-glucosamine, which inhibit the hemagglutination, PL-D1 had an ultraviolet-difference spectrum with maxima at 292-294 nm and 284-285 nm, attributed to the red shift of the tryptophan residue, suggesting the location of tryptophan residue(s) at or near saccharide-binding site of PL-D1.

Acetylglucosamine↗

The major histocompatibility complex in the turkey: do erythrocytes bear serologically detectable H antigens?

An attempt was made to identify erythrocyte cell surface antigens associated with the major histocompatibility complex in the turkey. Two turkey lines, A and B, from the University of Minnesota, putatively homozygous for different major histocompatibility complex alleles, were used for this study. A total of 79 birds were immunized either by skin grafting or by injection of homogenized skin preparation in Freund's incomplete adjuvant. Antisera produced with skin grafts and homogenized skin inoculated intramuscularly both contained red cell agglutinins of low titer. Because agglutination reactions were weak, no sera were suitable for use as line-specific typing fluids. Thus, we were unable to demonstrate that turkey erythrocytes contain serologically detectable major histocompatibility antigens corresponding to the B major histocompatibility system in the chicken or the H-2 system in mice. Rather, the turkey major histocompatibility complex is more like that in rabbits, dogs, monkeys and humans.

Animals↗

Survey of leptospirosis of small mammals in Thailand.

During 1999-2000, kidney tissues of approximately 15% of 1310 rodents trapped from northeastern provinces of Thailand were tested for the presence of leptospires. Our direct immunofluorescent assay (DFA) for detection of leptospires showed 100% sensitivity and 94% specificity with the culture data. Both methods identified R. norvegicus as the highest source of infection. Among isolated Leptospira, 137 were serotyped by cross agglutinin absorption and/or a microscopic agglutination, and gave some variations and similarities at the serovar level to the DFA results. DFA data demonstrated over half of the positive animals were infected with several serovars of Leptospira interrogans. A subsequent DFA study in Bangkok in 2002 revealed leptospiral infection in 33% of 42 rats and shrews. The most common infecting serovars were Autumnalis and Canicola identified in rural and urban animals, respectively. This finding suggests that wild small mammals may act as important sources of pathogenic leptospires and warrant active surveillance to understand the epidemiology of transmission and control of carrier animals.

Animals↗

Surface characteristics of Pseudomonas cepacia.

Two major surface characteristics of Pseudomonas cepacia were examined in this study: reactivity with lectins and hydrophobicity. The results indicated that the surfaces of P. cepacia strains are heterogeneous with regard to the distribution of lectin receptors. Only lima bean agglutinin was found to strongly agglutinate all strains. The strains were also heterogeneous with regard to hydrophobicity as determined by adhesion to hexadecane. The degree of hydrophobicity, however, was not significantly altered when selected strains were mixed with either fibronectin or bovine serum albumin. In addition, the strains exhibited no apparent affinities for buccal epithelial cells and gave no evidence for an ability to haemagglutinate human red cells.

Agglutination↗

Further studies on the cell populations of an intersex horse.

An intersex horse exhibiting cell types of different sex chromosome constitution was subjected to further studies in order to determine whether the house was a mosaic or a chimera. Cultures of gonadal tissue and peripheral blood revealed mainly 64/XX and 64/XY cells, the former predominating in both tissues. The frequency of drumstick-bearing poly-morphonuclear neutrophils in the intersex horse was similar to that noted in normal mares. Blood type analysis using 17 naturally occurring agglutinins and hemolysins revealed partial agglutinations with three antibodies for the factors of the A system (anti-A, anti-F, and anti-I), and partial hemolysis with anti-Fr(3) suggesting erythrocyte chimerism probably resulting from intrauterine interchange of blood cell precursors as noted in other domestic animals. On the other hand, the presence of XX and XY cells in cultures of gonads which in our intersex horse were apparently devoid of germ cells, would seem to indicate wholebody chimerism resulting from double fertilization or blastocyst fusion.

ABO Blood-Group System↗

Isolation and identification of leptospira hardjo from cattle in Argentina.

A serological evaluation was done on the prevalence of bovine leptospirosis in Argentina. In 1,857 serum samples obtained from the major cattle raising areas of the country, 59.1 percent showed leptospiral agglutinins in the microscopic-agglutination test. The most frequent leptospiral antigens showing antibody reactions were the hebdomadis group serotypes, of which 45.8 per cent of the sera reacted to Leptospira hardjo with titres ranging from 1:100 to 1:25,600. Six Leptospira isolations were made from 161 bovine kidneys collected at local abattoirs. Their isolation and subsequent identification as serotype L. hardjo is described. This study reports on L. hardjo in cattle of Argentina for the first time and confirms the need for improved cultural methodology for its isolation.

Agglutination Tests↗

c-kit is expressed by primitive human hematopoietic cells that give rise to colony-forming cells in stroma-dependent or cytokine-supplemented culture.

Using monoclonal antibody (MAB) YB5.B8, we have examined the expression of the c-kit protein, the receptor for the hematopoietic cytokine stem cell factor (SCF), on primitive hematopoietic cells. Bone marrow mononuclear cells (BMMNC) enriched for immature cells by differential agglutination using the lectin soybean agglutinin (SBA) were subjected to multiparameter fluorescence activated cell sorting (FACS) based on light-scattering properties, the expression of the c-kit protein and the CD34 antigen, and the retention of the vital fluorescent dye, Rhodamine 123 (Rh123). Sorted populations were assayed for their content of directly clonogenic progenitor cells (colony-forming units-granulocyte/macrophage [CFU-GM], burst-forming units-erythroid [BFU-E], and multipotential colony-forming units [CFU-Mix]) and for the presence of more primitive progenitor cells ("pre-CFU"). The latter were assayed by (1) their ability to initiate and sustain hematopoiesis in a standard stromal cell-dependent culture system and (2) their capacity for de novo generation of clonogenic progenitors in response to a combination of six recombinant hematopoietic cytokines in a stroma-independent suspension culture assay. A mean of 76% of CD34+ cells were found to coexpress c-kit. The majority of directly clonogenic cells (98% of CFU-GM, 98% of CFU-Mix, and 85% of BFU-E) were found in the CD34+c-kit+ fraction. Similarly, all pre-CFU were recovered in the CD34+c-kit+Rh123dull fraction, irrespective of whether the cells were maintained on marrow stromal cells or in cytokine-supplemented liquid culture. A mean of 87% (range 70-100%) of the CD34+Rh123dull cells also expressed c-kit. Since SCF has been reported to act as a growth factor for early lymphoid cells as well as myeloid cells, we looked for coexpression of c-kit and early lymphoid markers in the CD34+ population by multiparameter flow cytometry. Coexpression of c-kit on a minority of cells with markers of B or T lineages was observed. The majority of early lymphoid cells, however, appeared to lack c-kit expression. This was confirmed by the finding that only 4% of c-kit+CD34+ cells showed terminal deoxynucleotidyl transferase (TdT) activity, compared with 25% of the c-kit-CD34+ cells.

Antigens, CD↗

The production of anti-A1 agglutinins in A-like rabbits injected with human group a1 secretor saliva.

A-like and non-A-like rabbits were injected with human group A1 and A2 secretor saliva. The sera were then examined for their agglutinative capacity against human group A1, A2, B and O erythrocytes before and after sequential adsorption with group O, B and A2 erythrocytes. The A-like rabbits produced specific anti-A1 agglutinins when injected with group A1 saliva but not when injected with group A2 saliva. The non-A-like rabbits produced anti-A and anti-A1 agglutinins in response to the A1 antigen but only anti-A agglutinins when group A2 saliva was injected. These experiments support the interpretation that a qualitative difference exists between subgroups A1 and A2. The non-A-like rabbits also formed cross-reacting antibodies as shown by the increase in the agglutinins reactive with human group B red cells.

ABO Blood-Group System↗

Qualitative and quantitative interactions of lectins with untreated and neuraminidase-treated normal, wild-type, and temperature-sensitive polyoma-transformed fibroblasts.

The lectin receptors of confluently grown hamster BHK, wild type polyoma virus transformed PyBHK, and temperature-sensitive polyoma transformed ts3-PyBHK fibroblasts were investigated using cell agglutination, quantitative (125I)lectin binding, and ferritin-lectin labeling. PyBHK and permissively grown ts3-PyBHK cells agglutinated more strongly with Ricinus communis I agglutinin (RCA-I)compared to BHK and nonpermissively grown ts3-PyBHK, although saturation binding of (125I)RCA-I to these cells at 4 degrees resulted in a twofold difference in lectin-binding sites on BHK and nonpermissively grown ts3-PyBHK cells (1.0-1.3 x 10 7 sites/cell) compared to PyBHK and permissively grown ts3-PyBHK (0.4-0.6 x 10 7 sites/cell). These cells bound equivalent amounts of (125I)concanavalin A (0.8-1 x 10 7 sites/cell) and (125I)wheat germ agglutinin (1-2.2 x 10 7 sites/cell). Under these binding conditions little endocytosis occurred, as judged by the subsequent release of greater than 90% cell-bound (125I)RCA-I by the RCA-I inhibitor lactose and localization of ferritin-RCA-I exclusively to the extracellular plasma membrane surface. However, if the binding is performed at 22 degrees, only 50% of the bound lectin can be removed by lactose, and ferritin-RCA-I is localized inside the cell within endocytotic vesicles. The relative mobility of RCA-I receptors was examined on ts3-PyBHK cells by the ability of ferritin-RCA-I to induce clustering of its receptors at 22 degrees. RCA-I receptors on permissively grown ts3-PyBHK cells appeared to be more mobile than on nonpermissively grown cells. BHK and PyBHK cells were treated with neuraminidase, and the resulting enzyme-treated cells were assayed for lectin agglutinability and quantitative binding of RCA-I, concanavalin A, and wheat germ agglutinin. Neuraminidase treatment resulted in decreased concanavalin A and wheat germ agglutinability and a slight increase in RCA-I agglutinability. The enzyme-treated BHK and PyBHK cells bound less (125I)wheat germ agglutinin (2.8 x 10 6 and 2.2 x 10 6 sites/cell, respectively) and 2.5 and 6.2 times more (125I)RCA-I (2.5-3 x 10 7) and 3.5-4 x 10 7 sites/per cell, respectively). There was no change in the number of concanavalin A binding sites after neuraminidase treatment. The increase in RCA-I binding sites approximated the decrease in wheat germ agglutinin binding sites indicating that the predominant penultimate oligosaccharide residue to sialic acid on these cells is D-Gal.

Animals↗

In vitro oncospheral agglutination given by immune sera from mice infected, and rabbits injected, with eggs of Hymenolepis nana.

Oncospheral agglutination given by sera immunized with Hymenolepis nana eggs is described as a new way of assessing H. nana infection. All sera of mice which possessed acquired protective immunity against reinfection by H. nana eggs had the potency to induce oncospheral agglutination in vitro. Only oncospheres, which had been hatched, agglutinated, no agglutination occurred in sera from uninfected mice. Oncospheral agglutination was carried out by mixing 0-1 ml of serial two-fold dilutions of serum and 0-1 ml of Hanks' balanced salt solution containing about 600 hatched oncospheres. Titre of agglutinins was indicated as a reciprocal of the final dilution capable of giving agglutination clusters made of three or more oncospheres. Agglutinins developed within 14 days after a primary infection with 500 shell-free eggs. There was no rapid increase of agglutinins within 4 days following a secondary infection. The titre increase coincided with the increase in dosages of eggs. Agglutinins were thought to be immunoglobulins, because the potency of the serum to agglutinate oncospheres was extinguished after absorption of globulins with rabbit anti-mouse globulin serum. Agglutinins were produced in rabbits by intravenous injections of shell-free eggs. The titres of the rabbit sera were much higher than those of mouse sera.

Agglutination↗

Status of immunity of newborns against Yersinia enterocolitica: a preliminary report.

Out of 221 cord blood specimens assayed by whole cell agglutination for antibodies against Y. enterocolitica serogroup 0:3, 0:5,27, and 0:8, only four showed agglutinins despite the high percentage (33%) of agglutinating antibodies in 151 sera of pregnant women, ranging in titer from 4 to 32. Of 199 different cord sera tested, 25% to 28% showed low-level antibodies against erythrocytes treated with individual heat-extracts from Y. enterocolitica 0:3, 0:5,27, and 0:8. These sera equally agglutinated erythrocytes sensitized with the heat-extract of a randomly selected Escherichia coli strain. Conversely, when anti-yersinia hemagglutinins were absent in cord sera, concomitant cross-reactivity with E. coli was also absent. None of the 199 cord sera with a HA titer greater than or equal to 4 were reactive by whole cell agglutination. Under the test conditions used, CEA (common enterobacterial antigen) could be the main antigenic component to which the Y. enterocolitica hemagglutinins were directed. Nine of the reactive sera from pregnant women were treated with staphylococcal protein A with resultant loss of reactivity. Transplacentally acquired antibody directed primarily against the CEA antigen of Y. enterocolitica may protect the newborn against Y. enterocolitica infection.

Antibodies, Bacterial↗

[Microtiter agglutination test for salmonella and brucella antibodies (author's transl)].

To compare the tube agglutination test and the microtiter plate agglutination procedure, 207 human sera were tested for agglutinins to Salmonella and 267 sera for agglutinins to Brucella by both methods. A positive reaction in the microtiter test was indicated by a smooth or irregular mat shape at the bottom of each well in the microtiter plate, whereas a negative reaction was shown by a settling of the antigen to a button shape. As can be seen in table 1, identical titer or only one dilution difference between both tests were found in more than 93% of the samples tested. The plate test was easier to perform and saved time, space, antigen and serum. The microtiter-agglutination technique can, therefore, be recommended for the routine laboratory for serology.

Agglutination Tests↗

[Serological diagnosis of the species Haemophilus equigenitalis using the rapid agglutination and coagglutination method].

The method of rapid slide agglutination and coagglutination was tested in the detection of Haemophilus equigenitalis (Taylorella equigenitalis)--the causal agent of contagious equine metritis (CEM). It was demonstrated that both methods were suitable for the serological diagnosis of the species under study. The antisera obtained from rabbits immunized with Haemophilus equigenitalis strains treated in different ways were specific, but with different antibody titres. When cross reactions with other species of microorganisms were verified, the antisera did not react with any of the strains, even after binding them to protein A of the positive strain Staphylococcus aureus--Cowan I. Coagglutination was much more rapid and pronounced than the ordinary rapid agglutination test. It was characterized by a low consumption of specific antiserum. The specific antibodies bound to staphylococci were kept at the temperature of 4 degrees C for several months without losing agglutinin activity.

Agglutination Tests↗

Sexual agglutinins from the Chlamydomonas flagellar membrane. Partial purification and characterization.

Chlamydomonas sexual agglutinins have been quantitatively extracted from isolated flagella in vitro using the dialyzable nonionic detergent octyl-D-glucopyranoside and from cells in vivo with 12.5 mM EDTA. Both preparations elicit normal sexual responses from gametes of complementary, but not like, mating types. Extracts of vegetative cells and several agglutination-deficient (imp) mutants are totally inactive. Agglutinin activity is sensitive to trypsin, mild periodate oxidation, and heating at 60 degrees C for 1 min. These findings, coupled with the size of the molecule (it is excluded from Sepharose 6B and sediments as a 12 S particle in sucrose gradients) lead us to propose that the Chlamydomonas sexual agglutinins are large glycoproteins or glycoprotein aggregates which associate with the flagellar membrane in an extrinsic fashion. Partial purification of in vivo 125I-surface labeled EDTA extracts rules out several surface polypeptides, including the bulk of material migrating in the region of the major membrane glycoprotein (Mr 350,000), as agglutinin candidates and indicates that the active molecule is a minor component of the flagellar membrane. In addition, in vitro assays suggest a mechanism for in vivo sexual agglutination whereby stable adhesion is achieved by the active redistribution of agglutinins to the flagellar tips.

Agglutinins↗

Proposed standard agglutinating sera for typhoid and paratyphoid A and B fevers.

The preparation of seven Standard Agglutinating Sera considered suitable to serve as international standard preparations for use in the serodiagnosis of typhoid and paratyphoid infections are described, and proposals are made for their further examination on a collaborative international basis.Details are given of antigenic materials and immunizing procedures which should suffice to enable substandards, based on the proposed International Standards, to be prepared locally.With the aid of the proposed Standard Agglutinating Sera it is possible to determine the "Standard Agglutinin Titre" of a serum under examination by any technique of the agglutination test, provided that a suspension of average sensitivity is employed.

Agglutination Tests↗

Experimental induction of caprylate-dependent albumin antibodies.

To provide evidence for the immune nature of the albumin agglutination phenomenon or caprylate dependent albumin agglutinins (CDAA), rabbits were injected with native serum that had been incubated in a solution of sodium caprylate. Two of three rabbits responded with the production of CDAA, which in vitro behaved identical to human antisera. Human cells were agglutinated only when caprylate stabilized albumin was added to the cell/serum mixture or when caprylate free albumin plus sodium caprylate were used. The CDAA failed to agglutinate rabbit cells, although, both human adult and cord cells were agglutinated. These experiments indicate that the CDAA represent an immune response to native albumin that had been altered by caprylate.

Agglutination↗

Specificity of reagents directed to the Thomsen-Friedenreich antigen and their capacity to bind to the surface of human carcinoma cell lines.

The Thomsen-Friedenreich antigen (T-antigen) is a cryptic disaccharide structure on human erythrocytes and is supposed to be expressed in an unhidden form on carcinoma cells. We tested the ability of four anti-T reagents (i.e., peanut agglutinin, human and rabbit anti-T antisera, and monoclonal anti-T antibodies) to agglutinate neuraminidase treated human erythrocytes and compared their capacity to bind to the surface of human carcinoma cell lines or neuraminidase treated lymphocytes. We found that all of the reagents strongly agglutinated neuraminidase treated erythrocytes. In contrast, only peanut agglutinin and the monoclonal antibody bound to the surface of carcinoma cell lines and to neuraminidase treated lymphocytes. Peanut agglutinin was inhibited by D-galactose and is known to be specific for the T-disaccharide. The determinants on erythrocytes, lymphocytes, and carcinoma cells, recognized by peanut agglutinin, are resistant to trypsin treatment. The monoclonal antibody was specifically inhibited by phenyl-beta-D-galactoside. The binding sites on erythrocytes and lymphocytes for the monoclonal antibody can be removed by treatment with trypsin or Pronase. On the other hand, the binding sites on carcinoma cells are resistant to trypsin but can be removed with Pronase. In contrast to the peanut agglutinin binding sites on carcinoma cells the structures recognized by the monoclonal antibody cannot be further increased by neuraminidase treatment. Human and rabbit anti-T antisera did not bind to tumor cell surface or to neuraminidase treated lymphocytes. Hemagglutination of human anti-T could be inhibited by asialofetuin; the specificity of rabbit anti-T could not be established in this study. Hemagglutination with both antisera is resistant to trypsin but partially sensitive to Pronase treatment. These results indicate that each of the reagents has a distinct specificity and recognizes different antigenic determinants on different molecules. Only peanut agglutinin and monoclonal anti-T antibodies are able to detect common structures on the surface of neuraminidase treated erythrocytes and carcinoma cell lines.

Animals↗