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At least 37 records · Page 2Linked to original sources
PubMed1977

Thermodynamics of antibody-antigen reactions. 2. The binding of bivalent synthetic random coil antigens to antibodies having different antigen precipitating properties.

The objects of this study were the equine IgG and IgG(T) classes of antibodies with immunologic specificity for the dinitrophenyl group and bivalent antigens consisting of linear poly(ethylene glycol) polymers which terminated at both ends in dinitrophenyl groups. Complex formation between antibodies of both classes and one of several sharp fractions of antigen having number average molecular weights in the range 25 000 to 75 000 were studied by measuring the light scattered from solutions containing equimolar amounts (approximately 5 x 10(-6) mol/L) of one of the antibodies and one size fraction of antigen, and variable amounts of monovalent hapten. The data were analyzed in the context of a model that accounted for the formation of linear and cyclic complexes of all extents of aggregation. Two parameters in addition to the intrinsic antibody-dinitrophenyl group association constant were found to be necessary in the assumed equilibrium model to account for the behavior of the system. One of these accounted for the looses in configuration entropy that resulted when a random-coil polymer became bound at one end to a space-occupying antibody. The other was a ring closure factor for the formation of cyclic complexes. Ring closure factors for the formation of larger cyclic complexes (present in only small amounts under the conditions studied) were related to the ring closure factor for the formation of the smallest, which was found to increase as antigen size decreased, and for each antigen size to be consistently higher for IgG(T) antibody than for IgG antibody. Comparison of the theoretically estimated values of the two parameters within their measured values indicated that the average conformation of IgG antibodies in solution is open ("T" shaped) but the average inter-Fab are angle in IgG(T) antibodies is approximately 60 degrees or less.

Animals↗
PubMedDate not supplied

[Comparative immunologic and physico-chemical properties of neurospecific antigens--bull antigen D and rat antigen alpha].

Immunological and physicochemical properties were compared for water-soluble acid neurospecific antigens: D of the bull and alpha of the rat. During immunoelectrophoresis in agar gel antigen D migrates as two immunologically indentical fractions having a position of prealbumins and alpha-globulins of blood serum. Antigen D from the bull brain is incompletely immunologically identical with antigen alpha from the rat brain. The molecular weight of antigen D determined under conditions of Sephadex G-100 column gel chromatography is 73000.

Animals↗
PubMed1975

Study of the antigenic cross reactivity between carcinoembryonic antigen and "nonspecific cross reacting antigens" (NCA and NCA 2).

The immunochemical relationship between CEA, NCA and NCA 2 was studied in guinea-pigs. Strong cross reactions were found between these antigens, either in delayed or anaphylactic reactions. Some specific determinants for each antigen could still be demonstrated. Delayed hypersensitivity is likely to be due to the protein moiety of the molecules while anaphylactic reactivity could probably be related to their glucidic parts. Consequently, CEA and NCA have common antigenic determinants on their glucidic and peptidic moieties, perhaps more on the latter ones.

Anaphylaxis↗
PubMed1977

Nature of the antigenic complex recognized by T lymphocytes. IV. Inhibition of antigen-specific T cell proliferation by antibodies to stimulator macrophage Ia antigens.

We have previously demonstrated that nonimmune guinea pig T lymphocytes could be specifically sensitized with TNP-modified allogeneic macrophages after eliminating the alloreactive T cells with bromodeoxyuridine (BUdR) and light treatment. This procedure allowed the unique opportunity to use anti-Ia sera directed against the Ia antigens of only the stimulator macrophages or responder T cells to determine against which cell type anti-Ia would block TNP-specific stimulation. It was found that the TNP-specific DNA synthetic response of BUdR and light-treated T cells stimulated with TNP-modified allogeneic macrophages was totally eliminated by anti-Ia sera directed solely against the allogeneic stimulator macrophage. In contrast, anti-Ia sera directed only against the responder T cells had no effect on their response to TNP-modified allogeneic macrophages. These findings indicate that macrophage Ia antigens are required for efficient T cell-macrophage interactions and raise the possibility that T cell Ia antigens may not be required for collaboration with macrophages. This latter possibility was substantiated by experiments in which we show that treating T cells with anti-Ia sera and complement to remove the Ia-positive cells either before or after priming, or both, had no effect on their ability to be primed and restimulated with TNP-modified macrophages.

Animals↗
PubMed1976

[Modification of the immune reaction by antigen-immunosuppressive-agent conjugates. I. Tentative hypothesis for the induction of antigen-specific suppression by antigen-immunosuppressive-agent conjugates].

The most important mechanisms for the specific depression of immune reactions--immuno-tolerance, enhancement, transfer of antibodies, drug induced tolerance, immunological suicide, application of antibody-toxin-complexes--are discussed with regard to their possible application in the clinical practice. A tentative hypothesis for induction of antigen specific suppression is proposed, basing on the use of antigen-immunosuppressive agent-conjugates (AIC). Antigen binding lymphocytes are supposed to bind the AIC and to pick them up through endocytosis. After breakdown of the AIC in the lymphoid cells the free immunosuppressive agent can become effective causing damage to the specific cell clones.

Animals↗
PubMed1977

Comparison of Streptomyces albus muramidase-extracted streptococcal antigen with acid-extracted M antigen and with pepsin-extracted T antigen.

Purified Streptomyces albus lytic enzyme was used in an attempt to extract type-specific antigen from a type 1, group A streptococcus. The presumably type-specific antigen was purified by ammonium sulfate fractionation followed by chromatography on O-(carboxymethyl)-cellulose columns. Comparison of the enzyme-extracted substance with acid-extracted material showed it to be serologically different from M protein. In addition, the extract obtained by enzyme treatment was resistant to trypsin as well as to the lytic enzyme. It was inactivated partially by pepsin and totally by papain. Comparison of the enzyme extract with pepsin-extracted T antigen showed these two preparations to be serologically identical. Subtle differences in their susceptibility to heat and acid treatment were noted. Immunodiffusion analyses of acid-extracted M protein and pepsin-extracted T protein, as well as with the enzyme extract, clearly established that the M-protein preparation contained a component serologically identical with one of the precipitinogens common to the other two extracts.

Antibodies, Bacterial↗
PubMed1979

Evidence for antigenic distinctness of the Epstein--Barr virus-determined nuclear antigen and the Herpesvirus papio-determined nuclear antigen.

Previous serological evidence indicated that Epstein--Barr virus-determined nuclear antigen (EBNA) has cross reactive components with the herpesvirus papio-determined nuclear antigen (HUPNA) and, in addition, it has distinct components of its own, not present in HUPNA. In the present study, this hypothesis was studied by absorption experiments. Absorption of anti-EBNA positive human sera with EBNA abolished both anti-EBNA and anti-HUPNA reactivity. Absorption with HUPNA removed all anti-HUPNA reactivity but did not reduce anti-EBNA to any detectable degree, thus confirming the hypothesis.

Animals↗
PubMed1978

Antigen-specific T-cell-mediated suppression. I. Induction of L-glutamic acid60-L-alanine30-L-tyrosine10 specific suppressor T cells in vitro requires both antigen-specific T-cell-suppressor factor and antigen.

A combination of in vitro and in vivo techniques were used to explore the mode of action of both crude and purified suppressive extracts specific for the random copolymer L-giutamic acid(60)-L-alanine(30)-L-tyrosine(10) (GAT- T(s)F) obtained from nonresponder DBA/1 (H-2(q)) mice. Normal DBA/1 spleen cells were incubated under modified Mishell-Dutton culture conditions for 2 days together with crude or purified GAT-T(s)F, and in the presence or absence of free GAT. These cells were then washed extensively and 3 x 10(6) viable cells transferred to syngeneic recipients, which were challenged at the same time with the immunogenic form of GAT complexed to methylated bovine serum albumin (GAT-MBSA). GAT-specific IgG plaque-forming cells (PFC) in the spleen were assayed 7 days later. In agreement with earlier in vitro studies on the action of GAT-T(s)F, it was demonstrated that under these conditions, low concentrations of GAT-T(s)F stimulated the development of cells which, aider transfer, are able to suppress the GAT PFC response to GAT-MBSA. The cells responsible for this suppression were shown to be T lymphocytes by using nylon wool-purified T cells for suppressor cell induction and by eliminating suppressive activity in cells cultured with crude GAT-T(s)F by treatment with anti-Thy 1.2 plus C before transfer. The suppressor T cells act in a specific manner failing to suppress significantly either anti-sheep erythrocyte or trinitrophenyl-ovalbumin primary PFC responses. For the induction of GAT-specific suppressor T cells in culture, a moiety bearing H- 2(K(q) or I(q)) determinants and also GAT, either bound to the crude GAT- T(s)F or added in nanogram amounts to antigen (GAT)-free purified GAT-T(s)F, were both required.

Animals↗
PubMed1977

Biochemical studies of the common and restricted antigens, two neural cell surface antigens.

Two cell surface antigens on rat neural tumor cells are defined by antisera from mice immunized with a rat glioma cell line, 33B. The Common antigen is on rat brain and embryo, and is strongly expressed on the surface of all, or most, rat glioma and neuroblastoma cell lines and tumors. The other Restricted antigen is not present at detectable levels on normal rat tissues, but is on 33B, and on 11 other rat neural tumors or cell lines developed from such tumors, though many other tumors are negative. These 2 antigens are on cell membrane preparations from cells and tumors, and have been further characterized using a quantitative antigen assay. Both antigens are heat labile, and can be destroyed by digestion with proteolytic enzymes. The Common antigen is 10 times more sensitive than the restricted antigen to pronase digestion. Furthermore, spacially separate sites for the 2 antigens are indicated by blocking experiments with pepsin digested antisera. Attempts to purify these antigens further have been frustrated by loss of antigenic activity upon detergent-induced release from the membrane. The tissue and tumor distributions of recently described mouse and rat surface antigens are reviewed. Many of these antigens are present on both brain and kidney, but not on other tissues, though several are shared with embryonic cells or sperm. Several new antigens have been described which may be neuronal specific.

Animals↗
PubMed1979

Selective and unidirectional membrane redistribution of an H-2 antigen with an antibody-clustered viral antigen: relationship to mechanisms of cytotoxic T-cell interactions.

We have studied the co-redistribution of vesicular stomatitis virus (VSV) antigen and of individual H-2 antigens on the surfaces of mouse cells, and in parallel we have also used these VSV-infected cells as targets in cytotoxic T-cell killing experiments. Antibody-induced patching and capping of the VSV antigen caused an extensive co-patching and co-capping of the H-2Kb antigen but not of the H-2Db antigen. In reciprocal experiments, the antibody-induced patching of the H-2Kb or H-2Db antigen did not result in a co-patching of the VSV antigen. Radioimmunoassays showed that the relative numbers of H-2Kb, H-2Db, and VSV antigens on the surfaces of the cells exhibiting such nonreciprocal co-redistributions were closely similar. Furthermore, the H-2 restricted cytotoxic T-cell lysis of these target cells showed a marked preference for H-2Kb compared to H-2Db compatibility. We propose that the VSV and H-2 antigens are molecularly independent entities in the unpreturbed target cell membrane but that the antibody-induced clustering of the VSV antigen causes a selective and unidirectional co-redistribution (which we designate as syn-capping) of H-2Kb with the VSV antigen clusters. It is suggested that such a T-cell-induced syn-capping process involving an antigen and an H-2 molecule on the target cell may play a critical role in the mechanism of cytotoxic T-cell killing.

Antibodies, Viral↗
PubMed1979

Specific absorption of T lymphocytes committed to soluble protein antigens by incubation on antigen-pulsed macrophage monolayers.

Monolayers of macrophages (Mphi) pulsed with antigen were used as immunosorbents for T lymphocytes from guinea pigs primed to soluble protein antigens. T lymphocytes were cultured on the Mphi monolayers for 4 hr, then aspirated and reincubated on a fresh monolayer pulsed with the same antigen for a second and a third step. T lymphocytes so treated were selectively deprived of cells responding in assay for antigen-dependent proliferation against the antigen used for pulsing the absorbing monolayer, but maintained their response to other antigens. The lymphocytes adhering to the Mphi of the absorbing monolayer were capable of giving a full response to the antigen used for pulsing the Mphi of the monolyers. The proliferative response of F1 T lymphocytes to antigen in association with Mphi of either parental strain could be absorbed leaving the response to antigen in association with Mphi of the other parental strain. The absorption of the proliferative response was not inhibited by addition of excess soluble antigen to the medium of the absorption culture. Our results indicate that specific guinea pig T lymphocytes responding by proliferation to soluble protein antigens recognize and bind specifically to a complex of Ia antigen and protein antigen at the surface of the Mphi.

Absorption↗
PubMed1978

Comparative behavior of simian virus 40 T-antigen and of tumor-specific surface and transplantation antigens during partial purification.

The simian virus 40-specific T-antigen has been extracted from SV AL/N mouse embryo tissue culture cells by treatment with Triton X-100 detergent. The extracts contained tumor-specific transplantation antigen (TSTA) and tumor-specific surface antigen. These extracts were purified by ammonium sulfate precipitation and diethyl-aminoethyl cellulose and phosphocellulose column chromatography and were assayed for the three antigens. We found that T-antigen, TSTA, and much of the tumor-specific surface antigen copurified through all purification steps. This finding is consistent with previous suggestions of the close degree of homology that must exist between the protein species carrying these three antigenic determinants. The antibody-mediated cytolytic assay appears to detect a new type of antigen on the cell surface, different from T-antigen and TSTA; two antigenic fractions were obtained from the phosphocellulose column that had tumor-specific surface antigen activity, but one of these did not have T-antigen or TSTA activities.

Animals↗
PubMed1976

Selective adsorption of heterophile polyglycerophosphate antigen from antigen extracts of Streptococcus mutans and other gram-positive bacteria.

Hot saline extracts of Streptococcus mutans have been shown to contain antigenic substances which occasionally react nonspecifically with some antisera against whole cells of various serological groups and types of streptococci. Chromatography of the extract of S. mutans strain MT703 (serotype e) on a diethylaminoethyl-Sephadex A-25 column gave two principal antigens. One antigen was eluted without adsorption to the resin and was identified as the serotype-specific polysaccharide. The other antigen, which contained a large quantity of phosphorus, was absorbed to and released from the resin by gradient elution. It was reactive against the antisera specific for polyglycerophosphate (PGP) from group A Streptococcus pyogenes and/or S. mutans strain Ingbritt (type c). The PGP antigen was further purified by gel filtration with Sephadex G-75. Two peaks, PGP-1, and PGP-2, were obtained. Each possessed the same antigenic specificity to anti-PGP serum as shown by immunodiffusion. Chemical analyses revealed that the molar ratio of phosphorus to glycerol in both was about 1:1, although the protein content between the two was significantly different. PGP antigen was found to be widely distributed in hot saline extracts from various gram-positive bacteria, with a few exceptions. However, all gram-negative bacteria examined were free of PGP. The PGP in the hot saline extracts of various gram-positive bacteria possessed an essentially identical antigenic specificity. The addition of diethylaminoethyl-Sephadex A-25 resin to hot saline extracts successfully removed the cross-reacting PGP antigen. After adsorption of the extract from S. mutans, the supernatant contained only type-specific polysaccharide antigen, except type b, in which both type b-specific polysaccharide and PGP antigens were absorbed with the resin. This simple procedure should be useful for the removal of the PGP-type teichoic acid from antigen extracts of bacteria that contain uncharged polysaccharides.

Antigens, Bacterial↗
PubMed1979

Tumor-associated antigens of chemically-induced murine tumors; the emergence of MuLV and fetal antigens after serial passage in culture.

Using radioiodinated Staphylococcus aureus protein A [125I]SPA to measure syngeneic, allogeneic and heterogeneic IgG bound to murine tumor cells, we performed a serological analysis of surface antigens of 8 solid tumors and 2 leukemias of BALB/c mice (3 chemically-induced colon carcinomas, 3 chemically-induced sarcomas, 1 murine leukemia virus (MuLV) induced leukemia, 1 irradiation induced leukemia, 1 spontaneous melanoma and 1 spontaneous sarcoma). We were able to detect and distinguish between at least five separate antigenic specificities on these tumors. Unique tumor-associated antigens were found on 3 of the tumors, MuLV related antigens on 8 tumors, fetal antigens on 7 tumors and two distinct common antigens on 7 tumors (common antigen 1 (CA-1) on 5 tumors and common antigen 2 (CA-2) on 2 tumors). Neither of the common antigens was found to be sarcoma, carcinoma or tissue-tupe specific. A number of tumors which did not originally express either MuLV or fetal antigens in primary cultures expressed these antigens after several serial passages in vitro.

Animals↗
PubMed1975

Molecular relationship between private and public H-2 antigens as determined by antigen redistribution method.

Molecular relationship of public H-2 antigens 1, 5, 6, 8, 11, 13, 25, and 28 to private antigens controlled by K and D regions was studied using the technique of antibody-induced resistance to complement-mediated cytotoxicity. The results indicate physical association in the cell membrane between H-2 antigens 1 and 23 of H-2-a, 8 and 31 of H-2-d, 11 and 17 of H-2-q, 13 and 30 of H-2-q, 25 and 23 of H-2-k, and 28 and 31 of H-2-g. These results are in agreement with genetic mapping placing the determinants of antigens H-2.8, 11 and 25 in the K region , the determinant of antigen H-2.13 in the D region, and the determinants of antigens H-2.1 and 28 in either the K or the D region. In contrast to genetic mapping placing the determinant for antigen H-2.6 in the D region, we found that in the H-2-b haplotype the antigen is associated with K region antigen H-2.33 and H-2.32, and interpreted this result as evidence for two homologous H-2.5 sites controlled by opposite ends of the H-2 complex. Although the data do not prove that public antigens are carried by the same molecules as private ones, they demonstrate a close physical association in the membrane between the two groups of loci, K and D, coding for the first 33 classical H-2 antigens (with the exception of antigen H-2.7), and thus support the two-locus model. The data also support the duplication model of H-2 by demonstrating two homologous H-2.5 sites associated with K and D molecules.

Animals↗