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[Detection of circulating antigen and/or antigen-antibody complex by using McAb against surface membrane antigen of adult Schistosoma japonicum].

In the present paper, the results of detecting circulating antigen and/or antigen-antibody complexes by McAb against surface membrane antigen of adult Schistosoma japonicum were reported. The McAb, coded as 8SE4, was prepared by fusion of SP2/0 myeloma cells with spleen cells of the BALB/c mice immunized with the saline extract of adult S. japonicum. The 8SE4- directed antigen was proved to be located on the surface of the adult worm. After being purified by a DE52 column, 8SE4 was labelled with HRP and the conjugate (HRP-8SE4) was used in the test. For testing, the serum sample was first incubated with HRP-8SE4, then PEG (mw. 6,000) was added to precipitate the antigen-antibody complex. Upon centrifugation, OPD was added to the precipitate. Results were read by ELISA reader at 492nm. The OD value was found to be proportional to the amount of circulating antigen and/or antigen-antibody complexes. Results from 5 heavily infected (1,500-2,000 cercariae) rabbits showed that the OD values were raised significantly at the 6th week post infection, being 1.9-4.5 times higher than those before infection. The OD values of the 5 rabbits each lightly infected with 10-500 cercariae were also markedly raised 6 weeks post infection and reached the peak at the 8th week, then maintained in high levels until 11th week post infection. The worm burden of the 5 lightly infected rabbits were 4-326. No obvious correlations between OD values and worm loads were observed. The results suggested the existence of surface membrane-related antigen and/or antigen-antibody complexes in the circulation of infected rabbits.

Animals↗

Comparison of percent free prostate specific antigen and prostate specific antigen density as methods to enhance prostate specific antigen specificity in early prostate cancer detection in men with normal rectal examination and prostate specific antigen between 4.1 and 10 ng./ml.

PURPOSE: We analyzed the behavior of prostate specific antigen (PSA) density and percent free PSA to enhance the specificity of PSA in the early diagnosis of prostate cancer in men with normal digital rectal examination and PSA serum level between 4.1 and 10 ng./ml. MATERIALS AND METHODS: PSA serum level, PSA density and percent free PSA were analyzed in 74 men with normal digital rectal examination and PSA serum level between 4.1 and 10 ng./ml. All men underwent systematic prostate biopsy, and the diagnosis was benign prostate hyperplasia in 52 and prostate cancer in 22. Furthermore, we determined the decrease in unnecessary biopsies and the cancer detection rate using 0.10 versus 0.15 as cut points for PSA density, and 20 versus 25 as cut points for percent free PSA. RESULTS: In patients with benign prostatic hyperplasia and prostate cancer, respectively, the median PSA level was 6.7 and 7.0 ng./ml. (p > 0.05), median prostate volume was 50 and 37 cc (p < 0.04), median PSA density was 0.14 and 0.19 (p < 0.007) and median percent free PSA was 18.9 and 10.1 (p < 0.005). Using PSA density cut points of 0.15 and 0.10, the decrease in negative biopsies was 53.8 and 36.5% with a sensitivity of 86.4 and 90.9%, respectively. However, using percent free PSA cut points of 20 and 25, the decrease in negative biopsies was 36.5 and 26.9% with a sensitivity of 77.3 and 95.5%, respectively. CONCLUSIONS: Although both methods could minimize unnecessary biopsies in men with normal digital rectal examination and PSA serum level between 4.1 and 10 ng./ml., the percent free PSA was more cost-effective since transrectal ultrasound was not required. In this small series of symptomatic patients a percent free PSA cut point of 25 could detect at least 95% of prostate cancers and decrease 26.9% of negative biopsies.

Aged↗

Neonatal tolerance induction in the thymus to MHC-class II-associated antigens. I. Preferential induction of tolerance to Mls antigens and resistance to allo-MHC antigens.

Neonatal tolerance inducibility of self-major histocompatibility complex (MHC)-class II-associated antigens was compared with that of allo-class II antigens. BALB/c (H-2d, Mlsb) mice, less than 24 hr after birth, were intravenously injected with bone marrow cells of either (BALB/c X DBA/2)F1 (H-2d, Mlsb/a, semiallogeneic at the Mls locus) or (BALB/c X B10.BR)F1 (H-2d/k, Mlsb; semiallogeneic at the MHC), as antigens. The mice were tested for in vivo immune activity of class II-reactive T cells by means of the popliteal lymph node-swelling assay. They developed tolerance, irrespective of type of antigens, showing profoundly suppressed host-versus-graft reaction, and those tolerized to the allo-MHC antigens accepted skin grafts of the corresponding allogeneic mice. In the thymus and spleen of the Mls-tolerant mice, antigen-specific class II-reactive T-cell activity was completely abolished, without the apparent involvement of suppressor cells. In contrast, the activity in allo-MHC-tolerant mice was not reduced in either thymus or peripheral lymphoid organs, suggesting that systemic hyporesponsiveness is attributable to reversible suppression of immune competent cells. The resistance for cell-level tolerance induction to allo-class II antigens may not be ascribed to the active participation of allo-MHC antigens in prevention of or in escape from tolerance induction or both, since an injection of bone marrow cells of both Mls and H-2-semiallogeneic (DBA/2 X B10.BR)F1 (H-2d/k, Mlsa/b) mice could induce tolerance to Mlsa-H-2d antigens in newborn thymus cells.

Animals↗

Astrocytes as antigen-presenting cells. I. Induction of Ia antigen expression on astrocytes by T cells via immune interferon and its effect on antigen presentation.

Ia antigens seem to control immune responses on at least two levels. First, they influence the antigen recognition repertoire of the T cells. Second, their variable expression on certain antigen-presenting cells is a powerful regulatory mechanism for the local immune reaction. This is particularly important in the central nervous system (CNS) in which no Ia antigens are normally expressed. Recent experiments in this context have shown that astrocytes are able to express Ia antigens during interaction with T cells, and that they function as antigen-presenting cells. The Ia-inducing activity is produced by activated T cells, and can be replaced by immune interferon (IFN-gamma). In this study we report on the functional and kinetic relationship between Ia antigen expression on astrocytes and the immune-specific activation of T cells by astrocytes. Normal resting astrocytes were found to be negative for Ia antigens by immunofluorescence and by biochemical criteria. Moreover, they are only able to stimulate T cells after they have been induced to express Ia antigens by a signal from the T cells, which is probably mediated by IFN-gamma. In conclusion, the immune-specific interaction between astrocytes and T lymphocytes is a sensitively controlled system that might be pivotal to the development of immune responses in the brain. Malfunction of the system could be an important factor in the pathogenesis of aberrant immune reactions in the CNS, e.g., in multiple sclerosis.

Adjuvants, Immunologic↗

Presentation of antigen by B cell subsets. II. The role of CD5 B cells in the presentation of antigen to antigen-specific T cells.

We demonstrate that peritoneal B cells have a much higher ability to present antigen to antigen-specific T cell lines than splenic B cells. Presentation of antigen by B cells is abrogated or drastically reduced after removal of Lyb-5+ cells from the population of splenic or peritoneal B cells. Peritoneal B cells, precultured for 7 days prior to the antigen presentation assay, retain their antigen presenting cell (APC) function. Enrichment for CD5+ cells in the peritoneal B cell population results in a more effective antigen presentation. Lastly, stimulation of B cells via CD5 antigen, by treatment of cells with anti-CD5 antibodies or cross-linking of CD5 receptors, enhances APC function of these cells. The results indicate, both indirectly and directly, that CD5+ B cells play a predominant role in the presentation of conventional antigens to antigen-specific T cells.

Animals↗

Inhibitory effects of thymus-independent type 2 antigens on MHC class II-restricted antigen presentation: comparative analysis of carbohydrate structures and the antigen presenting cell.

The role of thymus-independent type 2 (TI-2) antigens (polysaccharides) on the MHC-II-restricted processing of protein antigens was studied in vitro. In general, antigen presentation is inhibited when both peritoneal and splenic macrophages (M phi) as well as Küpffer cells (KC) are preincubated with acidic polysaccharides or branched dextrans. However, the inhibitory effect of neutral polysaccharides was minimal when KC were used as antigen presenting cells (APC). Morphological evaluation of the uptake of fluoresceinated polysaccharides clearly correlates with this selective and differential interference. Polysaccharides do not block MHC-I-restricted antigen presentation. Some chemical characteristics shared by different saccharides seem to be specially related to their potential inhibitory abilities: (i) those where two anomeric carbon atoms of two interlinked sugars and (ii) those containing several sulfate groups per disaccharide repeating unit. No polysaccharide being inhibitory in M phi abrogated antigen processing in other APC: lipopolysaccharide-activated B cells, B lymphoma cells, or dendritic cells (DC). Using radiolabeled polysaccharides it was observed that DC and B cells incorporated less radioactivity as a function of time than M phi. Morphological evaluation of these different APC incubated for extended periods of time with inhibitory concentrations of polysaccharides revealed intense cytoplasmic vacuolization in M phi but not in B cells or DC. The large majority of M phi lysosomes containing polysaccharides fail to fuse with incoming endocytic vesicles and delivery of fluid-phase tracers was reduced, suggesting that indigestible carbohydrates reduced the fusion of these loaded lysosomes with endosomes containing recently internalized tracers. It is suggested that the main causes of this antigen presentation blockade are (i) the chemical characteristics of certain carbohydrates and whether the specific enzymatic machinery for their intracellular degradation exists; and (ii) the different phagocytic abilities of distinct APC populations, fluid-phase pinocytosis and receptor-mediated saccharide uptake, and existence of a differential antigen-processing pathway in M phi and DC or B cells, which could be based on a polysaccharide-inhibited step present in M phi but unaffected or irrelevant in both B cells and DC.

Animals↗

Facts on the fragmentation of antigens in presenting cells, on the association of antigen fragments with MHC molecules in cell-free systems, and speculation on the cell biology of antigen processing.

The processing of a protein antigen is a multi-step event taking place in antigen-presenting cells. Processing is a prerequisite for the recognition of most antigens by T lymphocytes. The antigen is ingested by endocytosis, transported to an acid cellular compartment and subjected to proteolytic fragmentation. Some of the antigen fragments bind to MHC class II molecules and are transported to the surface of the antigen-presenting cell where the actual presentation to T lymphocytes occurs. The nature of the processed antigen, how and where it is derived and subsequently becomes associated with MHC molecules are the questions discussed in this review. To us, the entire concept of processing has appeal not only because it explains some hitherto well-established, but poorly understood, phenomena such as the fact that T lymphocytes focus their attention entirely upon antigens on other cells. It has appeal also because processing allows for a thorough scrutiny of all the proteins of a cell including both the proteins which have been taken up from the environment (mostly MHC class II-restricted) and the cell's own proteins (mostly MHC class I-restricted). Through the mechanism of processing fragments of all these proteins including "internal" fragments which are not present on the globular protein's surface are brought out on the cell surface in association with MHC molecules and displayed to the T-lymphocyte system. This allows for the identification and, if necessary, the destruction of cells which in their interior harbor abnormal proteins, be they derived from virus-encoded genes or other abnormal genes.

Antigen-Antibody Complex↗

House dust mite (HDM) antigen in naturally occurring lesions of atopic dermatitis (AD): the relationship between HDM antigen in the skin and HDM antigen-specific IgE antibody.

To elucidate the etiological role of house dust mite (HDM) antigen in the pathogenesis of atopic dermatitis (AD), we conducted immunohistochemical studies on the localization of HDM antigen in naturally occurring lesions of AD. HDM antigens were found in the epidermis and dermis in 19 of 38 cases. All of the 19 patients had HDM antigen-specific IgE antibody, but HDM antigen was not detected in the lesions of patients without HDM antigen-specific IgE or in control skin specimens. Most HDM antigens were located on Langerhans cells (LCs) or near helper T cells. Our findings suggest that HDM antigen is the causative factor in the development of eczematous lesions of AD, and thus we hypothesized that IgE-mediated allergic contact sensitivity to HDM antigen plays an important role in the pathogenesis of AD.

Adolescent↗

Antigen-pulsed neutrophils bearing Ia antigens can induce T lymphocyte proliferative response to the syngeneic or semisyngeneic antigen-primed T lymphocytes.

Antigen-pulsed neutrophils from mouse peritoneal cavities displayed a remarkable level of lymphocyte proliferative activities to antigen-primed T lymphocytes. Genetic mapping studies demonstrated that compatibility at the I-A, as well as I-E/C, subregions of the major histocompatibility complex (MHC) was essential for effective presentation of the lysozyme antigen. These antigen-presenting activities were remarkably inhibited by anti-Ia sera. Inhibition tests revealed that neutrophil immune-associated (Ia) antigens seem to be essential for antigen presentation during the initial 8 hr. Elimination studies of antigen-pulsed neutrophils with alloantisera plus complement revealed these antigen-presenting neutrophils bearing both I-A and I-E/C gene products on the same cells. These results suggest that Ia-positive neutrophils might play a role in the immune response through antigen presentation.

Animals↗

Comparison of the Binax Legionella urinary antigen enzyme immunoassay (EIA) with the Biotest Legionella Urin antigen EIA for detection of Legionella antigen in both concentrated and nonconcentrated urine samples.

We evaluated a newly commercial enzyme immunoassay (EIA) (Biotest Legionella Urin Antigen EIA; Biotest AG, Dreieich, Germany) for detection of antigens of all Legionella pneumophila serogroups with a relatively wide spectrum of cross-reactivity as well as antigens of other Legionella spp. by comparing its sensitivity and specificity with those of an EIA for detection of L. pneumophila serogroup 1 antigen (Legionella urinary antigen EIA; Binax, Portland, Maine). Both tests were performed with both concentrated and nonconcentrated urine samples. We also evaluated the capabilities of both EIAs to detect extracted soluble antigens of American Type Culture Collection (ATCC) Legionella strains (L. pneumophila serogroups 1 to 14, L. bozemanii, and L. longbeachae). The sensitivity of the Biotest EIA was 66.66% in nonconcentrated urine and 86.66% in concentrated urine. The sensitivity of the Binax EIA was 63.76% and 88.88% in nonconcentrated and concentrated urine, respectively. The specificity was 100% in nonconcentrated and concentrated urine for both assays. The Binax EIA and Biotest EIA detected extracted soluble antigens of L. pneumophila serogroups 1 to 14 and L. bozemanii ATCC strains. The cross-reactions observed with the Binax EIA were probably due to common epitopes directly related to lipopolysaccharide. Further studies are required to determine the usefulness of the Binax EIA for detection of urinary antigens from Legionella species and serogroups other than L. pneumophila serogroup 1. The Biotest EIA proved to be as rapid, sensitive, and specific as the Binax EIA for the diagnosis of legionellosis. Concentration of antigen present in urine increased the sensitivities of both techniques with no reduction in specificity.

Adult↗

Preparation of Toxoplasma gondii RH strain antigen, antigen analysis and antigen detection in sera: a review.

The prevalence of antibodies detected by serology against Toxoplasma gondii in Indonesia is quite high. Therefore further research concerning the antigen used is important to improve the quality of the assay being used with lower cost. An attempt to prepare T. gondii strain RH antigen followed by using it in the ELISA procedure for detecting IgG showed that there was no significant difference between the local ELISA and Toxonostika quantitatively and qualitatively. Analysis of the antigen was done by Western blot, using sera collected from 30 clinically suspected toxoplasmosis cases which contained IgG only (titer ranging from 1:1,600-> or = 1:3,200); from 9 asymptomatic healthy person, from 5 cases consisted of 1 case of lymphadenitis (IgM titer > or = 1:3200 and IgG titer 1:800) and 4 cases of visual disturbances which had IgM with titer ranging from 1:800 to > or = 1:3,200 and IgG with titer ranging from 1:800 to > or = 1:3,200. It was shown that antigen components of 90, 87, 82, 72, 41, 26 and < or = 6 kDa reacted to all sera containing IgG except sera containing both IgG and IgM. Especially bands of 41 and 26 kDa showed strong reaction with all sera containing IgG, except 2 sera which contained both IgG (titer 1:800) and IgM (titer 1:800 and 1:3,200). These sera collected from 2 left eye vision disturbance cases were not reactive to all antigen components. Strong reactions against bands of 41, 26 and < or = 6 kDa were also shown in sera which contained only IgG collected from 9 healthy persons without any toxoplasmosis symptoms whereas bands of 90, 87, 82 and 72 kDa all showed moderate strong reaction. Contrasting to sera containing only IgG, of 5 sera containing both IgG and IgM 3 of them showed only reactions against bands of 41, 26 and < or = 6 kDa which were strong. It seemed that almost all sera containing IgG gave reaction to 90, 87, 82, 72, 41, 26 and < or = 6 kDa, however different pattern of reaction might occur, probably depending on the nature of infection as more antigen components would be recognized by sera containing IgG alone rather than sera containing both IgM in large quantity and IgG. In another study, an attempt to detect T. gondii antigen in 60 samples was done by using ELISA, and it was shown that circulating antigen was found in 27 (90%) from 30 samples which contained both IgG and IgM, whereas only 2 (66%) from 30 samples which contained only IgG showed positive results. Therefore, antigen detection can be used to identify the acute phase of infection.

Animals↗

New antigenic determinant common to human thymus leukaemia-associated antigens and common acute lymphoblastic leukaemia antigen.

In the present paper we demonstrate that there is an antigenic determinant common to two different types of human leukaemia-associated antigens, i.e. human thymus leukaemia-associated (HTL) antigens and common acute lymphoblastic leukaemia (cALL) antigen. In addition, there are distinct antigenic determinants which are unique to the HTL antigens or to the cALL antigen. The new, common antigenic determinant will be useful as a new differentiation marker of human haematopoietic cells as well as a new leukaemia-associated marker. In the present study, we used several different anti-human leukaemia antisera which include those prepared by immunizing rabbits (Nos. 7549 and 7550) with purified HTL antigens. The antisera 7549 and 7550, without any absorption, showed strong specificity as well as strong antibody activity toward leukaemia cells. These are the first anti-human leukaemia antisera, except for the monoclonal hybridoma antibodies, that show good specificity for leukaemia cells without prior absorption.

Animals↗

Immunological heterogeneity of carcinoembryonic antigen: antigenic determinants on carcinoembryonic antigen distinguished by monoclonal antibodies.

Murine monoclonal antibodies against carcinoembryonic antigen (CEA) derived from a colonic tumor were analyzed by radioimmunoassay for reactivity with CEA and the CEA-related antigens, meconium antigen (MA) and nonspecific cross-reacting antigen. Antibody-antigen binding profiles revealed three classes of hybridomas. The Class I antibody, NP-1, recognized an epitope shared among all three antigens, and its affinity for CEA and MA was high but low for nonspecific cross-reacting antigen. The Class II antibodies reacted with sites shared between CEA and MA, while those of the Class III type only bound CEA. The Class III antibody, NP-4, bound less than 50% of the CEA molecules recognized by goat specific anti-CEA antibody and the other classes of monoclonal antibodies. Two Class II antibodies, NP-2 and NP-3, bound similar amounts of CEA and MA with moderate but different affinities for CEA. Studies using labeled monoclonal antibodies for CEA epitope blocking revealed that NP-2 and NP-3 recognize two separate epitopes on CEA within the Class II category. Thus, monoclonal antibodies to CEA can differentiate at least four antigenic sites on colonic cancer CEA. One is shared by CEA, MA, and nonspecific cross-reacting antigen; two others are shared by CEA with MA; and a fourth appears specific for a subpopulation of CEA molecules.

Adenocarcinoma↗

Genetic mapping of the K1 and K4 antigens (L) of Escherichia coli. Non-allelism of K(L) antigens with K antigens of O8:K27(A), O8:K8(L) and O9:K57(B).

Escherichia donor strains having antigen K1(L) or K4(L) transfer these K antigens to recipient cells at a genetic locus (kps A) similar to that of K10(L) and K54(L) linked to ser A. In crosses between the K10 donor strain and recipient strains O8:K8(L), O8:K27(A) and O9:K57(B) all recombinants which inherit donor K antigen also inherit K antigen of recipient. This result is interpreted as non-allelism between donor and recipient K antigens, and it is assumed that the structure of all polysaccharide K antigens of strains having O antigens O8 or O9, whether termed L, A, or B, are controlled by genes which differ in their location on the chromosome from genes controlling polysaccharide K antigens associated with most other O antigens.

Antigens, Bacterial↗

Class II MHC/peptide complexes on T cell antigen-presenting cells: agonistic antigen recognition inhibits subsequent antigen presentation.

Previous studies have shown that tolerogenic anti-CD4 (W3/25) and anti-LFA-1 mAb (LRTC1) which block T cell activation paradoxically enhance T cell-mediated antigen presentation. Lasting T cell APC (T-APC) activity requires and initial exposure of T cells to these mAb in the presence of professional APC and antigen. This study revealed a central mechanism regulating the duration of T-APC activity. T cell recognition of class II MHC complexes of T-APC catalyzed a rapid decay in the presentation of agonistic antigens, whereas partial agonistic signals decayed at a shower rate. Likewise, blockade of agonistic T-T cell autorecognition by these mAb led to the persistence of agonistic MHC/antigen on T-APC. The best predictor of T-APC activity was related to the ability of clonal T cells to respond to antigen presented by neighboring T cells. Strong responders were inefficient T-APC, whereas inefficient responders were strong T-APC. Addition of irradiated myelin basic protein (MBP0-specific responders to T-APC cultures specifically inhibited the subsequent presentation of MBP but not conalbumin, and vice versa. T-APC presentation of antigen to responder T cells also resulted in reduced surface expression of class II MHC I-A glycoproteins on T-APC. These findings indicate that agonistic recognition of antigen of T-APC specifically inhibits subsequent presentation of that antigen, whereas antagonistic MHC/antigen complexes are preserved for an enduring T-APC activity.

Animals↗

Monoclonal antibodies against human leucocyte antigens. II. Antibodies against CD45 (T200), CD3 (T3), CD43, CD10 (CALLA), transferrin receptor (T9), a novel broadly expressed 18-kDa antigen (MEM-43) and a novel antigen of restricted expression (MEM-74).

The specificities of several monoclonal antibodies described by us earlier were determined more exactly: (1) antibodies MEM-31 and MEM-32 are directed against CD8 and CD5 T cell antigens, respectively: (2) MEM-15 and MEM-18 react with the CD14 monocyte antigen; (3) MEM-28 recognizes the CD45 pan-leucocyte antigen. Several new monoclonal antibodies are described: (4) MEM-55 and MEM-58, reactive with subsets of CD45-related molecules; (5) MEM-43, recognizing a broadly expressed 18-kDa glycoprotein; (6) MEM-57, reacting with the CD3 antigen complex: (7) MEM-59 recognizing the CD43 leucocyte antigen; (8) MEM-74, which reacts with an unidentified antigen strongly expressed on several cell lines and many leukaemic cells but absent from most resting leucocytes; (9) MEM-75, directed against transferrin receptor, and (10) MEM-78, recognizing CD10 (CALLA) antigen.

Antibodies, Monoclonal↗

Antigenic requirements for T-cell activation: reconstitution of a functional antigen from an inactive peptide portion of an antigen conjugated to protein carriers.

The structural features of an antigenic peptide required for T-cell activation were examined by a novel approach: an active antigen was constructed from an inactive peptide portion of the original antigen by conjugating it to various proteins. An eicosapeptide, peptide 8, representing residues 103-112 of the tobacco mosaic virus protein (TMVP), was utilized as the model antigen for these studies. While peptide 8 was able to stimulate, in vitro, T-cells from peptide 8 primed mice, synthetic peptides representing various portions of peptide 8 were unable to activate these cells. Although the amino-terminal undecapeptide of peptide 8 (residues 93-103 of TMVP) was unable to activate T-cells from peptide 8 primed mice, conjugates which consisted of this undecapeptide coupled to certain proteins were capable of inducing antigen-specific proliferation of these T-cells. These results identify two structural antigenic features essential for T-cell activation: a T-cell-recognizable epitope within the amino-terminal undecapeptide of peptide 8 and a second region provided by the carboxy-terminal half of peptide 8 or by protein carriers. Potential roles for this second region include providing a site for antigen interaction with Ia molecules on the antigen-presenting cell or, alternatively, providing amino acids important in stabilizing the binding of the T-cell antigen receptor. The results suggest that the recognition of this second region exhibits only a limited specificity.

Animals↗