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Biomedical subjects

B Benacerraf

Publications and source records attributed to B Benacerraf.

At least 307 records · Page 17Linked to original sources
PubMed1975

Specific and nonspecific antitumor immunity. I. Description of an in vitro assay based on inhibition of DNA synthesis in tumor cells.

As in vitro assay of cell-mediated antitumor immunity based on the inhibition of tumor cell DNA synthesis (IDS) was devised. It was reasoned that both cytolytic and cytostatic antitumor effects could be measured in a quantitative yet generalized manner with this approach. By the use of microculture techniques and simplified methods for the determination of tritiated-thymidine incorporation by all cells in individual cultures, normal and immune effector (E) cell populations were compared in their ability to inhibit the DNA synthesis of a fixed initial number of various target tumor cells. Doubling dilutions of E cells were used to titrate the antitumor effects of normal and immune cells at many E/T (effector to target) ratios. Under conditions of alloimmunization, significant immunologically specific IDS effects could routinely be detected at an E/T ratio of less than 1 or 0.1:1, and under certain conditions at 1:100 or less. Results were highly reproducible with respect to the individual E cell donors, replicate cultures, and repeat experiments. The effects were proportional to visually determined cell destruction and independent of obvious culture artifacts. The IDS method was compared with the 51Cr release technique under various experimental conditions. The results demonstrated that decreases in E/T ratio and/or the addition of excess nonimmune cells to immune effector populations had a similar effect in both assays, which was to decrease the magnitude of the immune cell activity. Addition of excess normal cells reduced the activity of immune cells to a level below that of an equal number of immune cells tested at the same E/T ratio without added nonimmune cells. Both assays detected primarily a T lymphocyte-mediated lytic event when effectors generated by the described alloimmunizations were used. The IDS assay also detected a weak non-T-cell activity in anti-theta plus complement-treated alloimmune spleen. The possibility that this represented antibody-dependent cell-mediated cytotoxicity was raised by the finding that normal spleen ceels plus antitarget antibody had significant activity in the IDS system. The sensitivities of the two methods were compared and the potential of the IDS method was evaluated.

Animals↗
PubMed1975

Specific and nonspecific antitumor immunity. II. Macrophage-mediated nonspecific effector activity induced by BCG and similar agents.

The recently described inhibition of DNA synthesis (IDS) assay, which measures antitumor effector (E) cell function by the quantitation of decreases in tritiated thymidine incorporation of target tumor cells, was used to analyze the nonspecific effector activity of peritoneal exudate cells (PEC) from mice infected intraperitoneally with BCG. These PEC could inhibit growth of and then kill all tumor target (effector to target) cells tested at E/T ratios as low as 1:1. This activity was not due to alterations in media, nor could any activity be shown for cell-free supernatants prepared from active cells. The principal cell type mediating this effector function was the "activated" macrophage-no activity was found in lymphoid or polymorphonuclear leukocytes. Direct effector to target contact was necessary for the cytotoxic reaction. The time course of these effects and comparative 51Cr release data were reported. The removal of the adherent nonspecific effectors from PEC of mice immunized to both BCG and a specific syngeneic tumor revealed a specific cytotoxicity of the remaining lymphoid cells. These results indicated that nonspecific effector activity by "activated" macrophages induced by BCG infection could be a potent antitumor mechanism, at least in vitro, and the IDS assay provided an accurate, reproducible, and quantitative method for measurement of the function of such E cells.

Animals↗
PubMed1975

Characterization of immune response and mixed lymphocyte reactions in selected intra-H-2 recombinant strains.

The genes controlling the immune response to the random linear terpolymers GAT and GLpro have been mapped in the Ir-1A or Ir-1B subregions with five lines of H-2-s/H-2-a recombinant mice. The I region also contains a third subregion, I-C, which codes for a lymphocyte-activating determinant, Lad2, controlling mixed lymphocyte reactivity. The mixed lymphocyte responses associated with I-C region disparity are compared with the stimulation noted with other H-2 region differences. Unidirectional lymphocyte activitation was associated with the Lad2 determinants in selected combinations.

Animals↗
PubMed1975

Induction of tolerance to nucleic acid determinants by administration of a complex of nucleoside D-glutamic acid and D-lysine (D-GL).

The administration of nucleosides coupled covalently to the copolymer of D-glutamic acid and D-lysine (D-GL) or to its stereoisomer, L-GL, induces a state of nucleoside (NUC)-specific tolerance in inbred SJL and BALB/c mice, irrespective of their immune status at the time of treatment. Such tolerance is characterized by the inability of treated animals to mount either primary or secondary, intact or adoptive, anti-NUC antibody responses following immunization with a highly immunogenic conjugate of NUC-Keyhole limpet hemocyanin. These observations have potential therapeutic importance in autoimmune processes involving anti-DNA antibody production.

Animals↗
PubMed1975

Induction of T lymphocyte responses to a small molecular weight antigen. I. Failure to induce tolerance in azobenzenearsonate (ABA)-specific T cells in guinea pigs with an ABA conjugate of A copolymer of D-glutamic acid and D-lysine (D-GL).

2,4-Dinitrophenyl (DNP) coupled to the copolymer D-glutamic acid and D-lysine (D-GL) induces B cell tolerance but not T cell tolerance. This implies either a lack of DNP determinant recognition by T cells or a substantial difference in tolerance mechanisms for the two cell types. In the present study D-GL was conjugated with the well-defined determinant azobenzenearsonate (ABA) coupled to single amino acids shown here and previously by others to trigger effectively T lymphocytes. The experiments presented here demonstrate that these ABA conjugates of D-GL, although capable of diminishing anti-ABA antibody production, completely fail to render ABA-specific T lymphocytes tolerant thus drawing us to conclude that there are significant operational differences in the mechanisms of tolerance induction in T and B lymphocytes, respectively.

Animals↗
PubMed1975

H-2-linked genetic control of resistance to histocompatible tumors.

The role of the major histocompatibility complex of the mouse (H-2) in resistance to two transplanted histocompatible tumors was evaluated by determining the differences in survival times between the syngeneic parent strain and various F1 hybrids. C57BL/10nSn (B10) mice and their F1 hybrids were given injections of a methylcholanthrene-induced fibrosarcoma of B10 origin. The B10 x B10.BR F1, B10 x B10.M F1, B10 x B10.WB F1, and B10 x 5R F1 hybrids survived significantly longer than the B10 parental strain or B10 x B10.D2 F1 and B10 x 18R F1 animals, while B10 x 2R F1 mice succumbed significantly sooner than any of the above groups. Statistical comparisons of geometric mean survival times of the strain of tumor origin (B10) versus the F1 hybrids showed the influence of genes coded for the H-2 complex in the phenomenon, termed "hybrid resistance" or "allogeneic inhibition." However, tumor resistance did not occur in all hybrids and could not be attributed to a single dominant Ir gene localized in the I region as might be predicted if the phenomenon involved genetic control of immunological responsiveness to tumor-specific transplantation antigens. Similarly, in a second group of experiments, the mean survival times of DBA/2 x B10.D2 F1 animals given injections of the 815 mastocytoma of DBA/2(D2) origin was compared to the mean survival times of various hybrids with the D2 parent. Again, the results demonstrated the importance of the H-2 gene complex in this phenomenon. However, the above results did not permit precise localization of the H-2-linked gene(s) responsible for differential resistance to the histocompatible tumor.

Animals↗
PubMed1974

Immune responses in vitro. XI. Suppression of primary IgM and IgG plaque-forming cell responses in vitro by alloantisera against leukocyte alloantigens.

The effects of alloantisera against leukocyte alloantigens on plaque-forming cell (PFC) responses to sheep erythrocytes and the terpolymer of L-glutamic acid(60)-L-alanine(30)-L-tyrosine(10) (GAT) by mouse spleen cells in vitro have been investigated. Polyspecific antibodies against both H-2 and non-H-2 alloantigens on responding spleen cells suppressed both IgM and IgG PFC responses; antisera against alloantigens coded for by the K and I regions, but not the D region, of the H-2 complex also effectively suppressed PFC responses. The suppression was not due to cytotoxicity to the spleen cells or anti-immunoglobulin activity in the sera and was directly related to the amount of antiserum added to the cultures. The suppression was specific for spleen cells against which the alloantiserum was directed. The alloantisera suppressed responses most effectively when present during the first 24 h of incubation, and although not rendering lymphoid cells incapable of developing PFC responses after removal of noncell-bound antibody, did act by interfering with successful initiation of the PFC response. The alloantisera suppressed both IgM and IgG PFC responses when directed against alloantigens only on macrophages, but selectively suppressed IgG responses when directed against alloantigens only on lymphoid cells. The alloantisera did not interfere with the ability of macrophages to bind GAT or to support the viability of the lymphoid cells, but did interfere with the ability of macrophage-associated antigen to effectively stimulate antibody responses by the lymphoid cells. Possible mechanisms for the effects of alloantisera on macrophages and the selective suppression of IgG responses when the antisera are directed against alloantigens on lymphoid cells are discussed with reference to our current understanding of genetic restrictions governing cell interactions in the development of antibody responses in mice.

Animals↗
PubMed1974

Genetic control of immune responses in vitro. V. Stimulation of suppressor T cells in nonresponder mice by the terpolymer L-glutamic acid 60-L-alanine 30-L-tyrosine 10 (GAT).

In recent studies we have found that GAT not only fails to elicit a GAT-specific response in nonresponder mice but also specifically decreases the ability of nonresponder mice to develop a GAT-specific PFC response to a subsequent challenge with GAT bound to the immunogenic carrier, MBSA. Studies presented in this paper demonstrate that B cells from nonresponder, DBA/1 mice rendered unresponsive by GAT in vivo can respond in vitro to GAT-MBSA if exogenous, carrier-primed T cells are added to the cultures. The unresponsiveness was shown to be the result of impaired carrier-specific helper T-cell function in the spleen cells of GAT-primed mice. Spleen cells from GAT-primed mice specifically suppressed the GAT-specific PFC response of spleen cells from normal DBA/1 mice incubated with GAT-MBSA. This suppression was prevented by pretreatment of GAT-primed spleen cells with anti-theta serum plus C or X irradiation. Identification of the suppressor cells as T cells was confirmed by the demonstration that suppressor cells were confined to the fraction of the column-purified lymphocytes which contained theta-positive cells and a few non-Ig-bearing cells. The significance of these data to our understanding of Ir-gene regulation of the immune response is discussed.

Alanine↗
PubMed1974

Characterization of a new intra-H-2 recombinant separation of the Ir-RE and Ir-GLT genes.

This report characterizes the intra-H-2 crossover in the D2.GD mouse strain. Recombination occurred within the I region between the immune response (Ir) gene controlling immune responsiveness to ragweed extract (RE). Ir-RE, and the Ir gene governing responsiveness to the random linear terpolymers of glutamic acid and lysine with either tyrosine or pheylalanine (Ir-GLT and Ir-GLphi). The Ir-RE gene was tentatively located in the Ir-1A subregion and the Ir-GLT and Ir-GLphi gene(s) tentatively placed in the Ir-1B subregion. The importance of this recombinant strain to further studies on the fine structure of the I region is discussed.

Allergens↗
PubMed1974

Genetic control of immune responses in vitro. 3. Tolerogenic properties of the terpolymer L-glutamic acid 60-L-alanine30-L-tyrosine10 (GAT) for spleen cells from nonresponder (H-2s and H-2q) mice.

Although nonresponder, H-2(s) and H-2(q), mice fail to develop GAT-specific PFC responses to GAT, they do develop GAT-specific PFC responses when stimulated by GAT complexed to an immunogenic carrier such as methylated bovine serum albumin. The studies described in this paper show that injection of nonresponder mice with GAT specifically decreases their ability to develop anti-GAT PFC responses to a subsequent challenge with GAT-MBSA. Addition of GAT to cultures of spleen cells from nonresponder mice also prevents development of the GAT-specific PFC responses stimulated by GAT-MBSA. Thus, interaction of nonresponder spleen cells with GAT leads to the induction of unresponsiveness in vivo and in vitro. Various parameters of the tolerance induction have been investigated and described. A comparison of the effects of GAT on B cells indicates that nonresponder B cells are more readily rendered unresponsive by soluble GAT than are responder B cells. The significance of these data for our understanding of Ir gene regulation of the immune response is discussed.

Alanine↗
PubMed1974

Genetic control of immune responses in vitro. IV. Conditions for cooperative interactions between nonresponder parental B cells and primed (responder plus nonresponder) F1 T cells in the development of an antibody response under Ir gene control in vitro.

The conditions for cooperative interactions between nonresponder B10.S B cells and GAT-primed irradiated (C57BL/6 x SJL)F(1) T cells in the response by cultures of mouse spleen cells to GAT were investigated. GAT-specific antibody responses could be elicited by soluble GAT in cultures of GAT-primed irradiated (C57BL/6 x SJL)F(1) T cells with C57BL/6 B cells but not with B10.S B cells. In contrast, when GAT was presented to the cultures on F(1) macrophages or as aggregates of GAT with MBSA, GAT-specific PFC responses were observed with both B10.S or C57BL/6 B cells. Irradiated GAT-primed T cells were nevertheless essential for the development of these responses. The GAT-specific response of B10.S B cells in these cultures was inhibited by the addition of soluble GAT at culture initiation. These results indicate that genetic disparity at Ir loci is not an absolute barrier to T-B-cell cooperative interactions in the response to antigens under Ir gene control. The significance of these data for the function of Ir gene products in immunocompetent cells is discussed.

Alanine↗
PubMed1974

Cell interactions between histoincompatible T and B lymphocytes. VI. Cooperative responses between lymphocytes derived from mouse donor strains differing at genes in the S and D regions of the H-2 complex.

In our initial studies on the question of histocompatibility requirements in T-B-cell interactions, we found that no cooperation occurred with mixtures of T and B cells from BALB/c (H-2(d)) and A/J (H-2(a)) donors, respectively (1). These particular strains are identical for genes in the S and D regions of the H-2 complex but possess major differences at the K-end. Many differences are known to exist in the I region as well. Thus, these early data indicated that gene identities only at the D-end are insufficient to permit optimal cooperative interactions to occur under these conditions.

Animals↗
PubMed1974

Immunological tolerance in bone marrow-derived lymphocytes. 3. Tolerance induction in primed B cells by hapten conjugates of unrelated immunogenic or "nonimmunogenic" carriers.

The present studies were designed to probe the role(s) of T cells in preventing or altering tolerance induction in hapten-specific B cells. This was accomplished by using hapten conjugates of normally immunogenic heterologous carriers to selectively inhibit 2,4-dinitrophenyl (DNP)-primed B cells in adoptive transfer experiments in vivo. The data provide strong indications that one critical role of T-cell participation in humoral responses to antigens is to circumvent the development of a tolerogenic signal that, in the absence of such T-cell function, might otherwise ensue after binding of the antigenic determinants by specific precursor B lymphocytes.

Animals↗
PubMed1974

Interruption of the sequential release of small and large molecules from tumor cells by low temperature during cytolysis mediated by immune T-cells or complement.

Specific lysis of tumor cells by thymus-derived lymphocytes from alloimmunized mice (T-effector specific lysis) was studied with target cells labeled with isotopes attached to both small ((14)C-labeled nicotinamide) and large ((51)Cr-labeled) molecules. The results confirm and extend previous reports that target cells release small molecules considerably earlier than large molecules during T-effector specific lysis. After interruption of T-effector specific lysis by specific antibody and complement directed against the killer cells, or by ethylenediaminetetraacetic acid, release of both isotopes continued, eventually reaching identical levels of specific release, the value of which represents the fraction of the target cell population which had been committed to die at the time these treatments were applied. On the other hand, release of both isotopes during T-effector specific lysis stops immediately when the cultures are cooled to 0 degrees . Thus, while ethylenediaminetetraacetic acid or specific complement-mediated lysis of the killer cells merely prevents the initiation of any new damage to target cells, cooling to 0 degrees also stops the lytic process in already-damaged target cells. The colloid osmotic phase of target cell lysis induced by specific antibody and complement was similarly stopped at 0 degrees in tumor cells, but not in erythrocytes. Thus, in tumor target cells, both T-effector specific lysis and complement cause a sequential release of progressively larger molecules which can be immediately stopped at any point by cooling to 0 degrees .

Animals↗
PubMed1974

The presence of I-region-associated antigens on B cells in molecules distinct from immunoglobulin and H-2K and H-2D.

The distribution of I-region-associated antigenic specificities in murine lymphoid cells was studied by immunofluorescence. The antigens were mostly represented in B cells and in macrophages. The complexes of I-anti-I-region-associated antigens were found to be distributed throughout the lymphocyte surface both at 4 degrees and 37 degrees . In about two-thirds of the lymphocytes the complexes redistributed into caps after incubation with a second ligand (an anti-mouse immunoglobulin). The I-region specificities were in molecules distinct from immunoglobulin or from the molecules coded by the H-2K and H-2D regions.

Animals↗
PubMed1974

Failure of lymphocytes to reexpress antigen receptors after brief interaction with a tolerogenic D-amino acid copolymer.

We present data concerning a strongly tolerogenic molecule made of a copolymer of D-amino acids that is not metabolizable poly(D-glutamic acid-D-lysine). The dinitrophenyl conjugate of this molecule induces profound tolerance in dinitrophenyl-specific B lymphocytes both in vivo and in vitro. We show that dinitrophenyl-poly(D-glutamic acid-D-lysine) binds to a population of lymphocytes including those specific for dinitrophenyl, that it persists for long periods on these lymphocytes and is poorly internalized by them, and that these lymphocytes are prevented from binding other dinitrophenyl compounds. Despite prolonged culture, they do not reexpress receptors for dinitrophenyl. This behavior of dinitrophenyl-poly(D-glutamic acid-D-lysine) is contrasted to that of metabolizable antigens. This finding indicates that one mechanism of tolerance induced by nonmetabolizable antigens involves the prolonged loss of B lymphocyte receptor function.

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