The mediator of cellular immunity. IX. The relationship between cellular hypersensitivity and acquired cellular resistance in rats infected with Listeria monocytogenes

The delayed hypersensitivity T cell and its interaction with other T cells

In this review Tony Nash and Philip Gell consider mainly recent work on the delayed hypersensitivity (DH) T cell (TDH) in mice, using viruses as infectious agents to probe the nature of DH and its relationship to protection.

Effect of the new immunostimulator HAB 439 on cell-mediated immunity against intracellular bacteria

The isoxazoline derivative HAB 439 was tested for its enzyme inhibiting potency and was found to be an inhibitor of aminopeptidase B (IC50 = 22.5 micrograms/ml). In further immunopharmacological experiments its efficacy to stimulate cell-mediated immunity was evaluated. HAB 439 was shown to stimulate DTH-reaction against Salmonella typhimurium and Listeria monocytogenes. HAB 439 protected animals against infection by reducing the bacterial load in livers and spleens and by decreasing the mortality rate. Treatment with the antibiotic ampicillin induced a decreased DTH-reaction in mice which was demonstrated to be due to a reduction of the antigen to be presented to the immune system and not to immune suppression. HAB 439 restored the impaired immune response to S. typhimurium and L. monocytogenes in a dose-dependent way. Restoration of DTH was shown to lead to an improvement of protection in ampicillin-treated mice which were challenged with the intracellular bacteria.

Transfer of resistance to primary infection of Listeria monocytogenes and early induction of delayed hypersensitivity by sera from L. monocytogenes-infected mice

We found a new phenomenon which differs from previous reports on experimental listeriosis, that is, failure of passive transfer of serum from Listeria monocytogenes-infected mice to convey resistance to the bacterium. Transfer of immune serum from L. monocytogenes-infected mice markedly augmented resistance to the bacterium, and mechanisms of the transfer of L. monocytogenes-immune serum were investigated. Transfer of immune serum prevented L. monocytogenes lethality. This effect of the immune serum was transferred dose dependently. Augmentation of resistance to L. monocytogenes also appeared in elimination of bacteria from the spleen. The growth of bacteria within 2 days in the spleen was not inhibited. Transfer of the immune serum augmented and accelerated induction of a delayed footpad reaction. Delayed hypersensitivity-dependent accumulation of mononuclear cells, detected by focus formation reaction in the liver, was also augmented. In contrast, polymorphonuclear cell accumulation in the liver was suppressed. Development of delayed hypersensitivity reactions was correlated with the elimination of bacteria in the spleens. These effects of the immune serum were expressed antigen specifically; however, the effector molecule(s) in the immune serum differs from immunoglobulin molecules.

Antigen-specific augmentation factor involved in murine delayed-type footpad reaction. II. Augmentation of delayed-type footpad reaction and acquired resistance to Listeria monocytogenes by transfer of Listeria-immune serum

We previously found an antigen-specific factor capable of augmenting delayed-type hypersensitivity (DTH) in the culture supernatant of the mixture of immune spleen cells and erythrocyte antigen, or in the serum of mice immunized with heterologous erythrocytes and exhibiting delayed-type footpad reaction. To elucidate whether this kind of factor (DTH-augmentation factor; DAF) participates in the establishment of DTH to various kinds of antigen besides erythrocyte antigen, we chose a bacterial antigen, Listeria monocytogenes, which is a facultative intracellular bacterium. In the present study, we demonstrated that the immune serum from mice immunized with viable Listeria augmented the delayed-type footpad reaction to Listeria. Furthermore, acquired resistance against Listeria was also augmented by the transfer of such immune serum. Such augmentation of acquired resistance was observed in sites infected locally and in the spleen of mice infected systemically. This effect was also seen in sera from mice immunized with heat-killed Listeria emulsified with complete Freund's adjuvant.

Delayed-type hypersensitivity to Babesia microti-infected erythrocytes in mice

Strong delayed-type hypersensitivity (DTH) to Babesia microti was elicited when intraerythrocytic parasites (IEP) were inoculated subcutaneously into the flank of normal mice 6 to 14 days before challenge in the ipsilateral footpad with 10(8) IEP. Intraperitoneal or intravenous administration of antigen did not sensitize mice for DTH. When challenge was given 21 days after immunization, the response was approximately half of the maximum and then rose again slowly over the next 3 weeks to levels that were not significantly different from those maximal values. The response was similar in seven strains of mice, regardless of sex. The response was classified as a true DTH reaction on the basis of kinetics, histology, and the transfer of responsiveness with immune T lymphocytes of the Ly 1+ phenotype, but not with serum. The reaction was specific for IEP since control groups given two injections of red blood cells from uninfected syngeneic mice (NRBC) or one injection of NRBC or sheep red blood cells (SRBC) and one of IEP never developed significant footpad swelling. Freed parasites obtained by osmotic rupture, density gradient sedimentation, and lethally irradiated IEP were also effective for elicitation of DTH. Anti-IEP DTH was expressed in a dose-dependent fashion with 10(6), 10(7), or 10(8) parasites sufficing for immunizing inoculum as long as 10(8) parasites were used as the challenge dose. Mice immunized and challenged with 10(8) lethally irradiated IEP (60 krad, 60Co), were protected against subsequent intraperitoneal challenge with 10(8) viable IEP. If mice were infected intraperitoneally with 10(8) IEP at any time between 21 days before immunization to 2 hr after challenge, their ability to respond to immunization and challenge was profoundly depressed. These data suggest that development of a strong anti-parasite DTH response can occur in parallel with resistance to infection, but is not a rapid sequela of bloodborne infection.

Chemical composition and biological functions of Listeria monocytogenes cell wall preparations

A crude Listeria cell wall fraction, a purified fraction (PF) with demonstrated biological activity, as well as a third fraction of base-hydrolyzed PF (BHPF) were analyzed for chemical composition and activities not previously described. Listeria cell wall fraction and PF contained significant quantities of lipid, whereas BHPF was lipid depleted. Fatty acid compositions were typical of gram-positive bacteria. PF and BHPF were depleted in protein. Alanine, glutamic acid, diaminopimelic acid, glucosamine, and muramic acid were found in all fractions, in enhanced concentration in PF and BHPF, and with molar ratios typical of bacterial peptidoglycans. Major neutral sugars were rhamnose, ribose, ribitol, and glucose. The concentrations of rhamnose, ribose, and glucose were increased in BHPF. Differences in chemical composition of the fractions reflected differences in their biological activities: Listeria cell wall fraction induced resistance to Listeria infection, whereas PF did not. Mitogenic and adjuvant activities were demonstrated for Listeria cell wall fraction and PF but were lost in BHPF. BHPF retained the ability to induce macrophage-mediated tumoricidal activity and decrease resistance to Listeria infection.

Lack of correlative enhancement of passive transfer of delayed-type hypersensitivity and antilisterial resistance when using concanavalin A-stimulated primed spleen cells

The adoptive transfer of resistance to Listeria monocytogenes can be significantly enhanced by in vitro incubation of primed murine spleen cells with concanavalin A (ConA) before transfer into syngeneic recipients. The level of transferred resistance, as measured by clearance of infectious organisms, can approach that observed in actively immunized mice. When delayed-type hypersensitivity (DTH) responses of passive transfer recipients were compared, there was no difference in the level of hypersensitivity exhibited by mice receiving either nonstimulated or ConA-stimulated, Listeria-immune spleen cells. In addition, the level of these adoptively transferred responses never approached the level of DTH observed in actively immunized mice. This inability of ConA-stimulated cells to enhance passive DTH in recipient mice was not dependent on the antigenic preparation of Listeria used to elicit the DTH response. Transfer of cultured, ConA-stimulated, Listeria-immune spleen cells did not lead either to specific or to nonspecific suppression of DTH responsiveness in actively immunized mice. These results indicate the possible existence of antigen-specific T-cells subpopulations which, after stimulation with ConA, exhibit differing efficiencies when responding in assays of cell-mediated immunity.

Regulation of delayed-type hypersensitivity. VII. The role of I-J subregion gene products in the inhibition of delayed-type hypersensitivity to major histocompatibility antigens by specific suppressor T cells

Suppressor T cells for delayed-type hypersensitivity (DTH) to alloantigens are induced by injecting mice intravenously with a high dose of X-irradiated allogenic cells. Using the same protocol, suppression of DTH directed against H-2 subregion products could also be induced, provided that the H-2 incompatibility between the cells used for the induction of suppression and the recipients includes the I-J subregion genes. Thus, the I-J subregion difference is both necessary and sufficient for the induction of suppression of DTH to the whole or part of the H-2 gene products. The suppression appears to be mediated by antigen-specific suppressor T cells which recognize the allo-I-J molecules and are able to suppress the DTH response to other H-2 subregion gene products in an associative recognition manner. T cells from (B10 x BALB/c)F1 mice suppressively primed against B10.A(5R) cells (directed against JkEk antigens), when adoptively transferred to normal syngeneic recipients, were capable of suppressing the hosts' DTH response to B10.A(4R) cells (KkAk antigens) when the recipients were challenged with [B10.A(4R) x B10.A(5R)]F1 cells (KkAk x JkEk). The recipients express normal DTH reactivity to B10.A(4R) cells when challenged with a mixture of B10.A(4R) cells (KkAk + JkEk). These results provide direct evidence that when functioning as alloantigens, the I-J determinants preferentially induce suppressor T cells which specifically impair the immune response to the I-J molecules as well as other H-2 gene products if they are physically associated with the I-J determinants. The role of I-J subregions as the suppressor genes is discussed in terms of the possible application in transplantation immunity and the host's defence against infectious diseases.

Delayed hypersensitivity reactions to Listeria monocytogenes in rats decomplemented with cobra factor and in C5-deficient mice

The in vivo effect of cobra factor (CoF), the complement-activating protein of cobra (Naja naja) venom, was investigated, using quantifiable assays for localization of labelled donor lymphoblasts and of host macrophages in intraperitoneal and subcutaneous sites of injection of antigens from Listeria monocytogenes. Both commercially available (Cordis) and highly purified CoF impaired these inflammatory responses, suggesting that the complement-activating protein was itself responsible rather than lymphocytotoxic or other contaminants. CoF had no measurable effect on lymphoblast localization during the first 7 hr, and only a slight effect at 24 hr, whereas macrophage accumulation was reduced by about 50% at 24 hr. This suggests that CoF treatment affected non-specific components of the early inflammatory reaction but had little or no effect on the subsequent immunospecific reaction. The effect of CoF on macrophages may be direct, or via depletion of complement components acting on macrophages, such as factor B and/or C3 or fragments thereof. It does not seem to involve the terminal complement components, C5--C9, since neither delayed-type hypersensitivity (DTH) nor cellular resistance to Listeria was reduced in C5-deficient mice when compared with C5-sufficient congenic controls.

Allogeneic restriction in the rat: genetic basis of restriction of the T cell mediators of delayed-type hypersensitivity and antimicrobial resistance to Listeria monocytogenes

The genetic basis of the restriction imposed on T cell mediating acquired antimicrobial resistance and delayed-type hypersensitivity (DTH) to Listeria in the rat was investigated. Sharing of MHC-coded genes between donors of sensitized T cells and antigen-stimulated recipients was both necessary and sufficient for efficient transfer of both resistance and DTH. Evidence to support this assumption was derived from experiments involving allogeneic transfers within major histocompatibility complex (MHC)-compatible strains and across MHC-barriers. Further support came from linkage studies with backcrossed rats and with the progeny of F1 rats mated with an unrelated strain. An unexpected difference in the compatibility requirements for effective transfer of DTH and resistance was noted in experiments involving the BI strain (formerly called B3). Thus, while B-region compatibility was obligatory for expression of DTH in recipients of sensitized T cells, considerable levels of protection could be transferred to either A-region or B-region compatible hosts.

Role of complement in the expression of delayed-type hypersensitivity in rats: studies with cobra venom factor

The hypothesis was tested that delayed-type hypersensitivity (DTH) to the complement-activating bacterium Listeria monocytogenes is initiated by complement-derived mediators that attract sensitized lymphocytes to reaction sites. To this end DTH and acquired resistance to L. monocytogenes were measured in rats injected with cobra venom factor, a potent inactivator of C3. Treatment with cobra venom factor reduced the hemolytic power of serum to less than 0.5% of the control value. Such decomplemented animals expressed both DTH and antimicrobial resistance, although expression of DTH was reduced (ca. 50%) when compared with complement-sufficient controls. The observed depression of DTH in cobra venom factor-treated rats was associated with a reduction in the number of recently activated lymphocytes (lymphoblasts) and macrophages that accumulated in DTH reaction sites. The above findings are explained, in part, by inhibition of inflammation during the early postinduction period. Supporting evidence came from measurements of labeled lymphoblast sequestration in saline injection sites and the slower accumulation of macrophages in nitrocellulose filters that were implanted subcutaneously in complement-depleted rats. The ability of cobra venom factor-treated rats to express DTH and protect themselves against a Listeria challenge seems to exclude C3-dependent factors as essential mediators in the attraction of antigen-reactive lymphocytes to reaction sites.

Cellular antimicrobial immunity

Acquired resistance to infectious disease may be expressed by a predominantly humoral or a cellular mechanism or, more frequently, by a combination of the two. The cellular interactions which are responsible for the induction of the immune response in the skin, lung, intestinal mucosa, genitourinary tract, conjunctiva, and peritoneal cavity are discussed and the role of living or dead vaccines in the induction of acquired resistance is outlined. The host response involves three different cell types: the phagocytic cell (polymorphs or macrophages), the thymus-dependent (T) lymphocyte, and the thymus-independent (B) lymphocyte-plasma cell line. The normal unstimulated phagocytic cell is capable of killing most nonpathogenic bacteria that gain entry to the tissues. However, the presence of opsonic antibodies and activated macrophages is required to eliminate the pathogenic intracellular parasites. Such immunological activation involves the presence of sensitized T-lymphocytes in the lesion. The cellular response is also characterized by the simultaneous development of a state of delayed-type hypersensitivity (DTH), along with the antimicrobial CMI response. A rising humoral response normally develops subsequently. Killed bacterial cells (except when incorporated into Freund's complete adjuvant) induce the humoral response without the CMI reaction so that such vaccines are not able to fully protect the host against the naturally acquired disease. With the development of cell fractionation methods as well as the identification of distinctive cell surface markers, suspensions of B- and T-cells and macrophages can now be prepared for use in increasingly sophisticated transfer and reconstitution studies. The role of the different cell types in the expression of humoral and cellular immunity has been determined, and the effect of various immunopotentiating and immunosuppressive regimens on the immune system as a whole has been evaluated quantitatively. These studies have led to an appreciation of the role played by suppressor B- and T-cells in the interplay of both humoral and cellular components of the host defense system during the development of immune tolerance, desensitization, anergy, autoimmunity, and the expression of an anamnestic immune response following reinfection.

Radiometric ear index test as a measure of delayed-type-hypersensitivity in the rat

Intradermal skin tests performed in the pinna of the rat ear appeared to be 100 times more sensitive than classical flank skin tests in measuring Arthus and delayed-type hypersensitivity (DTH) reactions. One of these tests was antigen-induced thickening of the pinna of the ear. It was found to be a sensitive measure of Arthus reactivity at 4 h after irritation with antigen in both actively immunized rats and recipients of precipitating immune serum. The other test, radiometric ear index determination, exploits the fact that monocytes and monocyte derived macrophages accumulate at DTH reaction sites. The test was performed by labelling the precursors of these cells with a pulse of [3H]-thymidine and by determining radioactivity in biopsy specimens taken from test sites in the pinna of the ear. At a certain antigen dose range this objective and highly sensitive method was shown to measure a purely cell mediated reaction which could be transferred to normal recipients with thoracic duct lymphocytes but not with immune serum. It also behaved as a typical DTH reacttion in response to desensitizing injections of the specific antigen. Testing with unnecessarily high antigen doses, however, should be avoided since the strong early inflammation induced by them may interfere with the determination of DTH while using this sensitive assay.

Appearance of cellular and humoral immunity in guinea pigs after infection with Coxiella burnetii administered in small-particle aerosols

The development of humoral and cell-mediated immune responses was studied in guinea pigs infected with Coxiella burnetti administered in small-particle aerosols. Direct macrophage migration inhibition was observed in cultured peritoneal exudate cells as early as 3 days after exposure. Maximum inhibition of macrophages cultured with phase I or II antigen occurred 14 to 21 days postexposure and persisted through 35 days. This inhibitory action was no longer detectable at 42 days. Serum antibody to the phase II antigen of C. burnetii was detected at 14 days, and serum antibody to phase I antigen was detected at 21 days, 18 days after the cell-mediated immune response.

The mediator of cellular immunity. XII. Inhibition of activated T cells by Newcastle disease virus

Newcastle disease virus (NDV) can interact in at least two ways with rat T cells. By adsorbing to circulating lymphocytes, the virus can transiently deflect the cells from lymph nodes and inflammatory exudates induced in the peritoneal cavity. T cells are affected regardless of age, state of activation, or position in the mitotic cycle. The effect is reversible and is mediated not only by infectious (I)-NDV, but also by UV-NDV which cannot achieve a complete replication cycle in eggs. But I-NDV has another lasting effect on activated T cells. It is revealed in the failure of virus-treated thoracic duct lymphocytes to transfer cellular resistance to Listeria monocytogenes, delayed-type hypersensitivity to soluble antigens of the parasite, and the permanent exclusion of labeled S-phase lymphocytes from inflammatory foci. Activated T cells are inhibited by virus multiplicites which have little if any effect upon the proliferative potential of antigen-sensitive T cells or localization of labeled small lymphocytes in lymph nodes. The underlying mechanism has not been determined; however, there are reasons for thinking that NDV has a lethal effect upon activated T cells, because the latter are permissive for virus replication.