Jacques M. Chiller

Effect of Immunological Unresponsiveness on Different Cell Populations

Specific immunological unresponsiveness is one of several possible states that is directed by contact of the host with antigen. The unresponsive state that the animal body enjoys to self constituents is probably the best example of antigen-directed immunological unresponsiveness. Similar unresponsive states, to a variety of heterologous antigens, have been induced in experimental animals. Since the injection of antigens usually induces an immune response, immunological unresponsiveness is induced only under selected conditions which determine the degree and duration of this unresfK>nsive state. Despite the diversified importance and practical potential of immunological unresponsiveness, little is known, of the mechanism involved in this state. However, the finding of Claman, Chaperon & Triplett (1966) and Miller & Mitchell (1967) that a collaboration between bone marrow and thymus-derived cells is required for an immune response and the observations that the macrophage may also participate in antibody production (Mosier 1967) permitted a cellular approach to elucidating the mechanism involved in several parameters of immunological unresponsiveness. For the most part, this chapter will be devoted to the role of various cell populations in the induction, maintenance, and termination of immunological unresponsiveness.

Induction of immunological tolerance in neonatal and adult rabbits differences in the cellular events

Abstract A transient production of antibody does not occur in the induction of specific immunological tolerance to soluble BSA in neonatal rabbits. The newborn rabbit, however, has the immunologic potential to respond to BSA when it is given in adjuvant. These results suggest that a normal complement of specific B cells is present in the newborn rabbit and that the immunoincompetence to the soluble protein, that permits the induction of tolerance without a phase of antibody formation, may be a function of either T cells or macrophages. In contrast to the newborn, the induction of tolerance in adult rabbits following daily injections with large doses of BSA is preceded by a transient production of antibody-producing cells. In this situation, at least, one of the events involved in the induction of unresponsiveness appears to be interpretable as an exhaustive differentiation of competent cells capable of being stimulated. Therefore, two differing cellular patterns can be observed in the completion of seemingly identical end states of immunological tolerance.

Cellular Basis of Immunological Unresponsiveness

Injection of an antigen into a vertebrate may be followed by a number of different immunological alternatives. Most commonly, a specific immune response is manifested in the form of cell-associated immunity, humoral immunity, or both. In other instances, antigen may specifically prime the challenged host without resulting in expression of a detectable immune response. Finally, antigen may induce the immunological antithesis of a responsive state, that is, a state of specific unresponsiveness. The specific cellular events involved in these differing pathways share at least one facet; i.e., initiation involves the interaction between antigen and a specific cell or cells. The present discussion will consider the experimental data concerning the cellular events and consequences of the interaction between antigen and antigen-reactive cells which lead to the state of specifically induced unresponsiveness. The emphasis will be placed on the cellular phenomena involved in the induction, maintenance, and termination of immunological unresponsiveness as it specifically relates to the block in the formation of humoral antibody.

MANIPULATION OF A TOLERANT STATE: CELLS AND SIGNALS

ABSTRACT The state of immunological unresponsiveness induced in mice with a tolerogenic form of the antigen human IgG can be cellularly characterized into phases of either T and B cell tolerance or T cell tolerance. In those circumstances when specific T cells appear tolerant while B cells are not, bacterial lipopolysaccharide (LPS) was able to modulate the biological effect of tolerogen from its capacity to induce tolerance to a capacity to induce specific immunity. This property of LPS was demonstrated under conditions where it could also act as a B cell mitogen. In two experimental situations in which LPS could be shown to be non-mitogenic, namely in the C3H/HeJ mouse strain or after chemical modification as a result of base hydrolysis, it could not affect the normal induction process of tolerance.

CELLULAR PARAMETERS OF THE TOLERANT STATE INDUCED TO HUMAN γ GLOBULIN IN MICE AND OF ITS MODULATION BY BACTERIAL LIPOPOLYSACCHARIDES

Publisher Summary This chapter discusses the cellular parameters of a tolerant state in mice to human γ globulin and its modulation by bacterial lipopolysaccharides. The theoretical genesis for the concept of clonal elimination stems from the necessity to provide a means for the biological basis of self-non-self discrimination. If the immune system can be viewed as a functional network of finely attuned regulatory mechanisms that suppresses rather than eliminates the potential for detrimental reactions, then the necessity for clonal deletion as the pathway by which self fails to be recognized may not be a biological prerequisite. Nevertheless, an attraction still exists for the evolutionary selection of a recognition system that can respond either positively or negatively depending on the conditions of interactions between cells and antigens. In this regard, an ontogenetic basis for self tolerance could be viewed as occurring at a stage in the course of lymphoid cell differentiation when a negative response is the only consequence that can result from a specific interaction between lymphocyte and antigen.

Unresponsiveness in hapten-specific cytotoxic lymphocytes: III. Influence of H-2 and Non-H-2 gene loci on the in vitro trinitrophenyl-specific CTL response following either acute or chronic in vivo treatment with trinitrobenzene sulfonic acid

The regulation of the in vitro generation of cytotoxic T lymphocytes (CTLs) directed against hapten-modified syngeneic cells has been investigated. The results indicate that acute intravenous pretreatment with water-soluble hapten, trinitrobenzene sulfonic acid (TNBS), can either positively or negatively affect the in vitro generation of trinitrophenyl (TNP)-specific CTLs. In general, mice bearing the H-2d haplotype are most likely to develop a reduced in vitro response pattern following a single acute in vivo TNBS treatment, wheras mice bearing the H-2k or H-2b haplotypes display either unchanged or augmented in vitro response patterns. We have shown that, in addition to the influences of H-2 genes, non-H-2 genes can also influence the in vitro hapten-specific CTL response following intravenous pretreatment with water-soluble hapten. Further, in two (H-2k X H-2d) F1 combinations between an H-2k strain displaying an unchanged in vitro response pattern following acute in vivo TNBS treatment and an H-2d strain displaying a reduced in vitro response pattern following similar treatment, it was observed that a single in vivo TNBS pretreatment did not induce the unresponsive state when F1-TNP stimulator cells were used. These results suggest that the mechanisms responsible for the reduced in vitro response pattern are not dominant within the F1 environment. However, when TNP-modified parental stimulators are used, a split-response pattern is observed in cells from TNBS-treated F1 mice which reflect the response patterns of the respective parents. These latter results again emphasize the influence of gene loci on the in vitro response patterns following acute TNBS treatment. In contrast to the significant influence of H-2 and non-H-2 genes on the in vitro TNP-specific response following acute in vivo TNBS treatment, these genes do not appear to significantly influence the in vitro TNP-specific response pattern following chronic TNBS treatment. Chronic TNBS treatment renders all strains tested specifically unresponsive.

Maturation of the lymphoid system IV. Ontogenetic compartmentalization of T cell function

Pretreatment of one day old but not eight day old or adult A/J mice with soluble ovalbumin (OVA) initiated specific T-cell unresponsiveness as reflected both in T-cell dependent cellular proliferation and in anti-hapten antibody responses to dinitrophenyl-OVA. In contrast, injection of soluble human gamma globulin into either neonatal or adult A/J mice resulted in unresponsiveness. The ability of lymph node T-cells to be sensitized by protein antigens occurred shortly after birth, since the degree of sensitization in 9 and 26 day old mice was similar. Finally, a striking ontogenetic difference was noted in the capacity of lymphocytes derived from the lymph nodes and spleens of young mice to respond to T-cell mitogens. Thus, while splenocytes obtained from 9 day old mice exhibited meager responses to PHA and Con A, lymph node cells from these animals responded at nearly adult levels. These observations are interpreted as reflecting an ontogenetic and tissue-specific division of T-cell function.

An in vitro model for induction of immunologic unresponsiveness to turkey γ-globulin in primed mouse spleen cells: II. Antigen-specific suppressor cells

Abstract Unresponsiveness induced to turkey γ-globulin (TGG) in cultures of TGG-primed spleen cells by incubation with high concentrations of soluble TGG (sTGG) was shown to involve a state of active suppression. Upon transfer to secondary cultures of primed spleen cells stimulated with an optimal dose of TGG-conjugated erythrocytes, such tolerant spleen cells were able to actively inhibit a secondary plaque-forming cell response to TGG in these cultures. Almost complete inhibition was observed with a tolerant cell to primed cell ratio of as low as 0.1. The suppression was antigen specific in that tolerant spleen cells which were suppressive for the secondary TGG response were unable to inhibit a primary response to sheep erythrocytes. T cells were shown to be required for the suppressor effect, in that (i) suppressor activity could be removed by complement-mediated lysis with an anti-Thy 1.2 antiserum and (ii) suppressor activity was retained in the effluent fraction after passage of suppressor spleen cells over a nylon wool column. Induction of the T-cell suppressor activity was found to be associated with a loss of T-cell helper activity within the TGG-pulsed cell population. The presence of adherent cells was not required for induction of suppressor activity. Furthermore, the suppressor effect was found to be resistant to 1000 R of γ irradiation.

An in vitro model for induction of immunological unresponsiveness to turkey γ-globulin in primed mouse spleen cells: I. The secondary in vitro response and induction of unresponsiveness☆

Abstract Spleen cells from mice previously immunized with turkey γ-globulin (TGG) were shown to give a vigorous secondary response in vitro when challenged in Mishell-Dutton cultures with TGG covalently coupled to pig erthrocytes (TGG-PRBC). However, 90–100% of the response could be abrogated by the incorporation of soluble TGG (sTGG) into the culture medium at concentrations greater than 1 mg/ml. Unresponsiveness, as measured by the absence of plaque-forming cells (PFC) in cultures receiving sTGG, was found to be antigen specific in that these cultures were still able to give normal PFC responses to sheep or burro erythrocytes. Spleen cells incubated with sTGG for short periods of time were shown to remain unresponsive after removal of sTGG from the culture and addition of TGG-PRBC. A 1-hr exposure period resulted in greater than 70% Unresponsiveness and a complete unresponsive state required only 8 hr of exposure. In contrast to the continued Unresponsiveness of sTGG-treated cells in vitro, spleen cells incubated with sTGG for 24 hr were fully responsive to an immunogenic challenge with alum-precipitated TGG when they were transferred into irradiated syngeneic mice. These data suggest that the readily induced unresponsive state in cultures of TGG primed cells may involve either a reversible antigen blockade of antigen-sensitive lymphocytes or a peripheral inhibition of reactive cells by suppressor lymphocytes.

Maturation of the lymphoid system. III. Induction of selective unresponsiveness by injection of a haptenated carbohydrate into neonatal mice

Neonatal treatment of A/J mice with DNP-Ficoll reduced or eliminated indirect anti-DNP PFC normally produced in response to adult challenge with DNP-keyhole limpet hemocyanin. The remaining direct anti-DNP PFC response was of low avidity. Spleen cells from neonatal A/J mice inhibited the in vitro but not the in vivo response of adult spleen cells to DNP-Ficoll.