Delayed hypersensitivity. V. The effect of x-irradiation on the development of delayed hypersensitivity and antibody formation

Hypersensitivity in newborn guinea pigs

Neonatal guinea pigs during the first 2 weeks of life did not indicate the presence of delayed hypersensitivity intradermally, after sensitization with purified soluble antigens in dose levels that induced detectable delayed hypersensitivity in the skin of adults. Although Arthus type allergy was detectable in newborns, circulating antibody frequently preceded its appearance by several days. Passive Arthus reactions were not produced in newborns as readily as in adults. Contact hypersensitivity and allergic encephalomyelitis were induced in newborns, but corneal reactions were not. Total body irradiation with 200 r inhibited antibody formation in newborns, as in adults. In addition, the induction period for anamnestic responses in newborns and the antigen elimination rate were the same as in adults. Passive transfer of delayed hypersensitivity from sensitized newborns to normal adults was accomplished.

A method for the selective beta-irradiation of individual lymphocyte microcultures and its application in a preliminary study of radiation sensitivity

A method that permits high energy beta-irradiation to be applied to individual lymphocyte microplate cultures is described. The principle involves the introduction of single energy sources (in this case 32P) contained within tubes which rest inside wells containing the lymphocyte cultures. Cell viability and mitogen-induced transformation were studied under these conditions. Dose-response effects were clearly demonstrated. The method is simple and, provided the precautions described are adhered to, safe. It should be applicable to studies of radiation sensitivity of putative target cells in various clinical situations.

The in vitro induction of delayed-type hypersensitivity to allo-antigens of the mouse

An in vitro procedure has been developed which allows the induction of delayed-type hypersensitivity (DTH) to major allo-antigens of the mouse. Murine spleen cells cultured with irradiated allogeneic cells develop allo-specific DTH reactivity (DTHR). The variables assessed to provide optimal induction of DTHR were (i) the culture system, (ii) the density of responders and the number of stimulator cells and (iii) the kinetics of induction. The reactivity of the allo-specific cells was assayed in 3 different ways in order to select the most sensitive: (i) by local footpad transfer into a mouse syngeneic with the responder cells together with the eliciting (irradiated) antigen-bearing cells; (ii) by local transfer into the footpad of a mouse syngeneic with the stimulator cells, in which the allo-antigens present in the subcutaneous tissues elicit the response, and (iii) by intravenous transfer into syngeneic or allogeneic mice which are challenged 24 h later in the footpad with spleen cells bearing the haplotype of the stimulator. The second assay is clearly the most sensitive (2X that of the first and greater than 20X that of the last). Observations are reported demonstrating the specificity of the swelling reaction. The kinetics of swelling and its T-cell dependence provide strong grounds for believing that the reaction is due to classical delayed-type hypersensitivity. Furthermore the T cells mediating the swelling are of the phenotype Lyt1+ Lyt2(+/-) and Ia- and are radiation resistant, whereas the ability to produce a swelling reaction is sensitive to 1000 rads. whole body irradiation. The system has been applied to determine both the specificity of T cells mediating DTH to major and minor allo-antigens and whether cytotoxic T cells (CTL) and DTH-active T cells are always induced under the same conditions.

Histophysiology of cellular immunity reactions in B-cell deprived rabbits. An X-irradiation model for delineation of an 'isolated T-cell system'

Three times sublethal total body X-irradiation with thymus shielding--at 2 weeks' intervals--delineated a temporarily B-cell deprived animal model, only reconstituted with recently thymus-derived cells. The thymusdependent areas of peripheral lymphoid tissue-repleted with T-cells--are described. The cellular immune capacity of these animals with an "isolated T-cell system" was analyzed by means of skin allografting. Histological and autoradiographic studies were performed in draining lymph nodes after a variety of antigenic stimuli: skin allografts, S. java vaccin, horse-gamma-globulin, horse spleen ferritin and a contact sensitizer (Oxazolone).

The role of the host immune response in the development of tissue lesions associated with African trypanosomiasis in mice

A variety of tissue lesions occurs in African trypanosomiasis, in the pathogenesis of which direct toxic effects of the parasite as well as immunological mechanisms may be involved. The purpose of the present study was to evaluate the role of the host immune response in inducing tissue damage in this disease and particularly in the production of lesions in striated muscle. The development of muscle lesions in T. brucei infection was studied in several groups of mice with different forms of immunodeficiency, as well as in normal mice. In the normal mice, foci of intense inflammation and necrosis were found in the cardiac and skeletal muscles 2 weeks or more after infection. In these lesions, there was a heavy deposition of IgG and IgM, and of trypanosomal antigens. In irradiated, newborn mice, and athymic nude mice infected with T. brucei, these inflammatory lesions were not found, although large numbers of trypanosomes were present between the muscle fibres. The characteristic lesions could be induced in athymic nude mice by transfer of normal spleen cells or of normal T lymphocytes 1 week after the onset of infection. The lesions were also partly induced by transfer of antibody to T. brucei. No antibodies to tissue components, particularly to cardiac myofibrils, were found in any of the infected mice. The results of this study show that immunodeficiency suppresses the development of the characteristic muscle lesions of African trypanosomiasis. The relative importance of humoral and cellular immune mechanisms in the pathogenesis of these lesions is not year clear.

The release of an endogenous pyrogen from guinea pig leukocytes in vitro: a new model for investigating the role of lymphocytes in fevers induced by antigen in hosts with delayed hypersensitivity

Guinea pig periotoneal exudate (PE) cells incubated overnight in vitro with heat-killed Staphylococci released an endogenous pyrogen (EP) that could be assayed by intravenous injection in rabbits. The febrile responses were linearly related to the dosage of EP over an eightfold range. PE cells derived from guinea pigs with delayed hypersensitivity (DH) to bovine gamma globulin (BGG), also released EP when incubated with antigen in vitro. This reaction was specific and did not occur withe PE cells from normal or complete Freund's adjuvant-sensitized guinea pigs. Studies indicated that monos and/or polymorphonuclear leukocytes rather than lymphocytes were the source of EP. However, when incubated with BGG and sufficient dosages of BGG-sensitized lymphocytes, normal PE cells released EP over a 42 h period. These results suggest that antigen stimulates specifically sensitized lymphocytes to release an agent (perhaps a lymphokine) that activates phagocytic cells to release EP. This model offers unique advantages for investigating in vitro the role of the lymphocyte in antigen-induced fever in DH as well as the relationship of this lymphocyte-induced activity to other known biologic activities mediated by antigen stimulated lymphocytes.

The relation between the cell-mediated immunological response and the induction of circulating antibodies to collagen in guinea-pigs

Cutaneous delayed hypersensitivity reactions to collagen in guinea-pigs were partially but specifically suppressed if the animals had been pretreated with collagen and Freund's incomplete adjuvant. Such animals responded normally to skin-reactive factor prepared with ovalbumin. Lymphoid cells from animals with normal delayed hypersensitivity to collagen functioned normally in animals with suppressed skin reactivity. Cells from animals with suppressed delayed hypersensitivity were specifically, functionally impaired since they transferred delayed hypersensitivity into neutral recipients efficiently for PPD but not for collagen. Suppression could be induced in Cy-treated animals, and it persisted for at least 143 days. It is concluded that guinea-pigs with depressed delayed hypersensitivity to collagen are functionally impaired with respect to those T cells normally generated by induction of delayed hypersensitivity.

Effect of immunosuppression on chronic LCM virus infection of mice

C3H mice chronically infected with LCM virus were found to be lethally affected by small doses of immunosuppression which caused bone marrow aplasia but had no effect on the amount of virus carried by the mouse. Humoral immune response of SWR/J mice to acute LCM infection was found to be totally suppressed by repeated single doses of 300 R/wk with no alteration in the level of virus carried by the mouse. In contrast, the established anti-LCM humoral immune response encountered in mice chronically infected with LCM virus was not suppressed by the same irradiation procedure. Over half of the chronic LCM carrier SWR/J mice treated with cyclophosphamide for 6 mo had total anti-LCM humoral immunosuppression, but showed no change in the level of virus carried. The glomerulonephritis which occurs in chronic LCM carrier mice was prevented by cyclophosphamide treatment in 90% of the mice. The humoral immune response which occurs in chronic LCM carrier mice appears to play no role in controlling the amount of virus carried by the mouse. Suppression of the LCM immune response by cyclophosphamide does prevent the development of glomerulonephritis in these mice.

In vitro studies of the cell-bound and antibody-mediated immunity evoked by murine renal allotransplants. Influence of presensitization, total body irradiation and immunosuppressive agents

The influence of presensitization, total body irradiation and several immunosuppressive drugs on the immune response evoked by allogeneic rat kidneys was studied in vitro and in vivo. The cytotoxic effect of recipient thoracic duct lymphoid cells and fresh or heat-inactivated recipient serum against donor target cells was measured with ⁵¹Cr assay.

Rats that had undergone two consecutive allogeneic transplantations from isogenous donors had thoracic duct lymphoid cells and serum with an increased cytotoxic effect against donor strain target cells as compared to control rats transplanted only once. Heat-inactivated recipient serum from such animals also had an increased blocking effect on cell-mediated cytotoxicity.

ALS had the strongest depressive effect on the cell-bound immunological responses evoked by the transplants in the recipient rats, decreasing both the number of lymphoid cells in the thoracic duct lymph and the cytotoxic activity of the remaining cells. Methylprednisolone and methotrexate also strongly suppressed the cellular immunological events in the way just mentioned. Actinomycin-C and total body irradiation depressed cell-bound immune response only by causing a decrease in the number of cells in the thoracic duct lymph. Azathioprine did not influence cell-bound immunological responses to allogeneic kidney transplants.

Total body irradiation, methotrexate and methylprednisolone treatment markedly diminished the cytotoxic effect of fresh recipient serum against target cells and reduced the blocking effect of heat-inactivated recipient serum on lymphoid cell-mediated cytotoxicity. The other tested agents all caused a moderate depression of the cytotoxic and blocking effect of fresh and heat-inactivated recipient serum, respectively.

When folinic acid was given regularly between consecutive methotrexate injections, the depression of the lymphoid cell amount in the thoracic duct lymph was markedly less. The results of the cytotoxicity tests were similar to those obtained with methotrexate treatment alone.

Studies on the mechanism of fever accompanying delayed hypersensitivity. The role of the sensitized lymphocyte

Experiments have been carried out to investigate the possible role of the sensitized lymphocyte in mediating the fevers of delayed hypersensitivity. Rabbits were made delayed hypersensitive to one of several heterologous proteins (bovine gamma globulin, bovine serum albumin, or human serum albumin) by footpad injection of antigen or antigen conjugated with dinitrophenol and incorporated in complete Freund's adjuvant. At intervals after sensitization, various tissues were removed, and single cell suspensions were incubated overnight with either carrier protein or conjugate in vitro. Release of an endogenous pyrogen (EP) was assayed by intravenous injection of the supernatant fluid into unsensitized rabbits. Of the tissues tested only those containing both lymphocytes and pyrogen-producing cells, blood, spleen, and draining lymph nodes, released detectable amounts of EP when incubated with antigen in vitro. Incubation of normal blood cells with specifically sensitized lymphocytes and antigen also resulted in significant release of pyrogen. Similarly, blood leukocytes released EP in vitro after mixture with supernates derived from incubation of sensitized lymphocytes and antigen. Cells and supernatant fluids from draining lymph nodes were usually effective in activating normal blood leukocytes earlier after sensitization than were those from mesenteric lymph nodes, suggesting that such cells, or antigen, had migrated from the original site of sensitization. The activator was soluble, nonpyrogenic in the dosages tested, and required incubation of viable cells with specific antigen for its production. These properties suggest that it may belong to the class of "lymphokines," biologically active agents released from lymphocytes that have been activated by immunologic or certain nonimmunologic stimuli.

Selective and specific inhibition of 24 hour skin reactions in the guinea-pig. 3. Depression of cytophilic and haemolytic antibodies by pretreatment with antigen and the effect of irradiation

Dvorak and Flax (1966) and others reported that adult guinea-pigs pretreated with soluble antigens showed depressed immune responses following immunization with the same antigens in Freund's complete adjuvant. These depressed immune responses included haemolytic and cytophilic antibody and delayed hypersensitivity as well as antibody measured by passive cutaneous anaphylaxis and haemagglutination. This communication describes further studies on the effect of pretreatment with alum precipitated bovine γ-globulin rather than soluble antigen. Guinea-pigs given 1 mg of alum precipitated bovine γ-globulin prior to immunization with 50 μg bovine γ-globulin (BGG) in Freund's complete adjuvant show depressed haemolytic and cytophilic antibody and delayed hypersensitivity. This depression is immunologically specific as pretreatment with alum precipitated egg albumin does not depress immune responses to bovine γ-globulin. In contrast, antibody measured by passive cutaneous anaphylaxis and haemagglutination is either unaffected or raised.

Similarly, pretreatment with sheep red cells reduces the cytophilic antibody response to sheep red cells in Freund's complete adjuvant.

This depression is long lasting and 1 mg alum precipitated BGG depressed the haemolytic antibody response to BGG in adjuvant given 6 months later and the delayed hypersensitivity response to BGG in adjuvant given 9 months later. Alum precipitated BGG given up to 6 days after immunization with BGG in adjuvant caused some depression of haemolytic antibody. However, this depression was transient and much less than the long lasting depression caused by pretreatment with alum precipitated BGG 7 days before immunization with BGG in adjuvant.

The effect of irradiation followed by alum precipitated BGG on the immune responses to BGG in Freund's complete adjuvant was also studied. 300 r depressed haemolytic and haemagglutinating antibody but had no effect on cytophilic antibody or delayed hypersensitivity. There was no synergy between irradiation and pretreatment with BGG; the depression of immune responses caused by irradiation followed by alum precipitated BGG was no greater than the depression caused by the more effective agent when given alone.

On the number and nature of antigen-sensitive lymphocytes in the blood of delayed-hypersensitive human donors

The virus plaque assay has been successfully employed to enumerate antigen-sensitive cells in the peripheral blood lymphocyte populations of tuberculin-hypersensitive human donors. The method is based on the finding that, while resting lymphocytes are unable to produce a variety of viruses upon infection, lymphocytes activated by specific antigens become capable of virus replication. The average number of antigen-sensitive cells detected in cell populations from donors reacting to first test strength or intermediate test strength tuberculin was approximately 3.6/1000 lymphocytes, and the averages for both groups were similar. Studies on the kinetics of appearance of these virus plaque-forming cells and on the effects of the mitotic inhibitor, vinblastine, indicate that the activation of these antigen-sensitive cells is a linear process and that the cells must be nondividing cells during this process. These qualities contrast markedly with those described for the mitogenic response and the antibody-producing cells which require cell division and increase exponentially. On the basis of these experiments it is suggested that the antigen-sensitive cell measured in the virus plaque assay is the effector cell in delayed-type hypersensitivity reactions and, in addition, may be one of the cells critically involved in antibody formation.

Effects of antimacrophage, antithymocyte, antilymphocyte and antispleen serum on the immune response in mice

The effect of antimacrophage serum (AMS) on antibody production was compared to that of antithymocyte (ATS) and antilymphocyte (ALS) serum. All three types of antisera inhibited antibody production to SRBC in mice. Antispleen serum was not immunosuppressive. Immunosuppression could best be demonstrated when the antisera were injected 3 days before a low dose of antigen (10⁷ or 5 × 10⁷ SRBC). None of the antisera affected secondary antibody production.

There was no correlation between the immunosuppressive potency of the antisera and their in vitro cytotoxic or in vivo lymphopenic acitivity. AMS inhibited phagocytosis, whereas ATS and ALS enhanced phagocytosis. So far we have been unable to absorb out immunosuppressive activity of the antisera but have been able to absorb out cytotoxic activity. The significance of these findings is discussed.

Cells involved in cell-mediated and transplantation immunity. II. A consideration of the functional identity of the cells involved in both humoral and cell-mediated immunity: a phylogenetic approach

The literature concerned with the types of cells that participate in the humoral and cell-mediated immune response has been reviewed. It is postulated that the initial cells that are involved in mediating both types of immunity are functionally identical in that both are antigen-reactive cells. In the case of the humoral immune response, the interaction of the antigen-reactive cells with the antigen leads to the release or transfer of "information" to the antibody-forming cell, resulting in the synthesis and secretion of antibody molecules. In the case of cell-mediated immunity, it is considered that the primitive antigen-reactive cell itself transforms into the sensitized cell which infiltrates the site of antigen administration.

Inhibition of granuloma formation around Schistosoma mansoni eggs. IV. X-irradiation

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Effect of phytohaemagglutinin on the immune response

The effect of phytohaemagglutinin (PHA) on the immune response of mice and rats has been investigated. A marked depression of anti-sheep erythrocyte agglutinin titres was found in both species following primary immunization. The decrease in titre was due to a depression of 2-mercaptoethanol resistant antibodies. The treated rats also developed antibodies against the haemagglutinating component of PHA.

PHA produced no depression of the delayed hypersensitivity response to tuberculin; nor did it suppress adjuvant arthritis in the rat. Histological examination of the lymphoid organs of PHA treated mice revealed reactive hyperplasia. Similar histological changes were seen in mice injected at the same time with a strong antigen such as horse ferritin. The depressive effect of PHA on IgG antibody formation and the absence of an effect on IgM antibody formation, delayed hypersensitivity, and adjuvant arthritis are discussed.

The effect of irradiation on the passive transfer of delayed hypersensitivity

Delayed hypersensitivity was passively transferred in guinea-pigs by lymph node and peritoneal exudate cells. This transfer was unaffected by irradiation with 1000 r given in vitro but was reduced by 1500, 2000 and 3000 r.

Quantitative studies on tissue transplantation immunity. 8. The effects of irradiation

This paper describes and attempts to interpret the effects of X- and gamma-irradiation on transplantation immunity. Whole-body irradiation prolongs the life ofA-strain skin homografts onCBAmice. Over the range 0 to 600 r the reciprocal of their survival time (x) is simply proportional to the applied radiation dosage (y), so that 1/x= 1/a–ky, wherearepresents the survival time of the homografts on unirradiated mice, andkis a constant of proportionality. At all doses skin homografts lasted significantly longer on males than on females, behaviour attributed to a higher intrinsic immunological reactivity of females rather than to a higher radioresistance. The normal lymphocyte transfer (NLT) reaction—an immunological response of the graft-versus-host type aroused by injecting lymphoid cells from one guinea-pig into the skin of another—has been made the basis of a more detailed investigation of how irradiation affects transplantation immunity. Lymphoid cells were exposed to a60Co radiation source eitherin vitro, i.e. in transit between donor and recipient, or in the donor before cell transfer, or in the recipient after cell transfer. As an entirely separate consideration, all lymphocyte recipients were exposed to 600 r whole-body irradiation before transfer to allow the NLT reaction to run a full course without the immunological opposition which the lymphocytes would otherwise arouse as homografts. Applied to transferred lymphocytesin vitroorin vivo, radiation dosages up to at least 1000 r did not affect the first inflammatory episode of the NLT reaction, i.e. the specific immunological event thought to mark the first recognition of antigen (see the preceding paper); nor did it affect the immediate immunological performance of lymphoid cells which had been presensitized against the guinea-pigs into which they were injected. The effect of radiation was only to suppress (at lower doses) or to abolish (at higher doses) the ‘flare-up’ episode of the NLT reaction, i.e. the conversion of a normal into a sensitized population, presumably as a result of cell division. It is accordingly argued that irradiation affects no distinctively immunological performance of lymphoid cells, and that the effects of irradiation can be explained by (a) its antiproliferative action, and (b) the fact that lymphocytes, though abnormally radiosensitive, acquire a relatively high degree of radioresistance as soon as exposure to antigen commits them to an immunological response. Members of a lymphoid population which have survived exposure to 600 r whole-body irradiationini vivo24 h beforehand perform more strongly than normal lymphoid cells in the NLT reaction. Internal evidence does not make it possible to decide between several possible interpretations of this fact.

Role of the thymus in tolerance. I. Tolerance to bovine gamma globulin in thymectomized, irradiated rats grafted with thymus from tolerant donors

Rats thymectomized and irradiated as adults were restored to immunologic reactivity by grafts of normal adult rat thymus and bone marrow. Reactivity of the delayed (cellular) type and formation of mercaptoethanol-sensitive (MES) and mercaptoethanol-resistant (MER) antibody returned within 3 weeks, while Arthus reactivity remained subnormal till 9 weeks after irradiation and grafting. When the thymus donor was tolerant to BGG, the recipient showed specific non-reactivity to this antigen 3 weeks and, to a much lesser extent, 6 weeks after grafting. This non-reactivity affected delayed responses and MER antibody. No effect was noted on Arthus reactivity and a slight effect on MES antibody. Controls showed that the non-reactivity was not due to transfer of free antigen at the time of grafting. It was concluded that different source organs are responsible for different immune functions and that specific immunologic tolerance may be induced within such an organ as the thymus.

The effect of irradiation on the fever of delayed hypersensitivity

The effect of total body irradiation on the development of delayed hypersensitivity and on the febrile response to specific antigen has been studied in guinea-pigs with the following results:

1. 200 R. whole body irradiation in guinea-pigs, while suppressing circulating antibody response, did not prevent the development of delayed hypersensitivity.

2. Irradiated and non-irradiated hypersensitive animals had an equal febrile response to systemic challenge with specific antigen.

3. Serum from antigen-challenged, irradiated, hypersensitive animals contained a pyrogenic factor of the endogenous serum type capable of producing fever in normal recipients.

These results support the conclusion that production of circulating specific antibody is not essential either for development of delayed hypersensitivity or for the febrile response of the hypersensitive animal to specific antigen.

NON-SPECIFIC INHIBITION OF THE IMMEDIATE AND DELAYED TYPES OF HYPERSENSITIVITY DURING IMMUNE PARALYSIS OF ADULT GUINEA-PIGS

Immunological paralysis induced in adult guinea-pigs with various protein overloading treatments is specific only at the beginning and soon after the end of the paralysis-inducing treatment. Reported experiments show that during a period which starts between the 8th and 10th days of the paralysing treatment and finishes when this treatment is discontinued, there is established an unresponsiveness towards antigens unrelated to the paralysing one. This non-specific unresponsiveness is manifested by the inhibition of reactions of both immediate and delayed types of hypersensitivity, at least to certain antigens.