Validation of the Candida albicans delayed-type hypersensitivity (DTH) model in the female B6C3F1 mouse for use in immunotoxicological investigations

Although numerous models are used to evaluate the immunotoxic effects of xenobiotics on cell-mediated immunity (CMI), no holistic model for evaluating such effects on the delayed-type hypersensitivity (DTH) response has gained widespread acceptance. Due to a lack of interference from antigen-specific antibody production, the Candida albicans DTH model has recently been demonstrated to be a more appropriate model for assessing effects on CMI than other DTH models that utilize different sensitizing antigens, such as sheep erythrocytes (SRBC) or keyhole limpet hemocyanin (KLH). The present studies were conducted to validate the C. albicans DTH model for its ability to detect suppression (or the lack thereof) of CMI following exposure for 28 days to well-characterized immunosuppressive drugs, each having a different mechanism of action. The compounds evaluated included azathioprine (AZA), cyclophosphamide (CPS), cyclosporin A (CSA), dexamethasone (DEX), and the non-immunotoxic compound, benzo[e]pyrene (B[e]P). Exposure to each of the four known immunotoxicants resulted in statistically significant decreases in the DTH response to C. albicans. Footpad swelling was decreased following exposure to AZA at ≥ 20?mg/kg but not at 10?mg/kg, CPS at ≥ 10?mg/kg but not at 5?mg/kg, CSA at ≥ 3?mg/kg but not at 1?mg/kg, or DEX at ≥ 0.3?mg/kg (intermittently at 0.1?mg/kg) but not at 0.03?mg/kg. As expected, exposure to B[e]P for 28 days at doses up to 40?mg/kg had no effect on the DTH response. These results demonstrated that the C. albicans DTH assay in the B₆C₃F₁ mouse was capable of appropriately classifying each test article as to its immunotoxic effects on CMI. Furthermore, comparisons of these results with previous reports of effects on ex vivo CMI end points suggest that this DTH assay may be more sensitive than standard ex vivo assays at detecting immunosuppressive effects.     

Cyclosporin A prevents suppression of delayed-type hypersensitivity in mice immunized with high-dose sheep erythrocytes.

When administered intraperitoneally to mice 2 days before immunization with a tolerogenic dose (10(9)) of sheep red blood cells (SRBC), cyclosporin A (CsA; 200 mg/kg) strikingly augmented 4-day delayed-type hypersensitivity (DTH) footpad reactions. These enhanced responses were similar in magnitude to those seen in animals sensitized with an immunogenic, low-dose (10(6)) SRBC. The stimulatory effect of CsA was observed over the dose range of 5-200 mg/kg and was obtained in animals given the drug in one injection, up to 7 days before sensitization. The augmentation of DTH was characterized by footpad swelling, intense mononuclear cell infiltration and increased deposition of 125I-fibrinogen within the challenge site. In addition, increased expression of procoagulant activity by spleen cells in response to antigen was observed. Cell transfer experiments showed that the CsA-enhanced DTH could be adoptively transferred to naive recipients. Additional transfers conducted at the time of antigen challenge suggested that, under the conditions described, CsA inhibited the action of a population of suppressor cells normally effective during DTH reactions.     

Cellular immune response to sheep erythrocytes: interrelationship between proliferation of popliteal lymph node cells and footpad swelling

Mice were sensitized with graded doses of sheep erythrocytes by the intravenous or subcutaneous route and challenged for delayed-type hypersensitivity (DTH) at different times thereafter. The DTH response as assessed by footpad swelling (FPS) was compared to the spontaneous proliferative response of the popliteal lymph node cells (PLNC). Proliferation of PLNC was optimal after sensitization regimens resulting in optimal FPS. The same was true for mice sensitized under cyclophosphamide modulation. Proliferation of PLNC induced by SRBC was antigen-specific, although some crossreactivity with horse red blood cells was observed. Proliferation of PLNC could be abrogated by treatment with anti-Thy-1.2 antiserum plus complement demonstrating the T cell nature of proliferating cells. In accordance with published data, FPS of mice presensitized with a high dose of SRBC as well as FPS of recipients of spleen cells from high-dose-sensitized donors was suppressed. In marked contrast, PLNC proliferation was not diminished in these mice. Although proliferation of PLNC did not parallel FPS under all circumstances, it seems to be a correlate of the cellular immune response to SRBC.     

Altered immune response (humoral and delayed-type hypersensitivity reactions) to sheep red blood cells in the course of experimental filarial infections (Litomosoides carinii,Brugia malayi,Acanthocheilonema viteae) ofMastomys natalensis

Litomosoides carinii-, Acanthocheilonema viteae- orBrugia malayi-infectedMastomys natalensis were sensitised against sheep red blood cells (SRBC) on various occasions after infection to determine the effect of filarial infections on the immune response to a non-filarial antigen. The phagocytic activity of the reticuloendothelial system (RES) was controlled in vivo by the elimination of⁵¹Cr-labelled SRBC. Antibody titres against SRBC (agglutinating and lytic antibodies) were similar to those of uninfected controls inL. carinii-orB. malayi-infectedMastomys sensitised during prepatency or early patency up to 90 days post infection (p.i.) but were reduced in animals sensitised during patency. A significant inverse correlation existed between anti-SRBC antibody titres and microfilaraemia levels. In contrast,A. viteae-infectedMastomys showed reduced humoral anti-SRBC responses at the end of prepatency, whereas the response tended towards normal with increasing parasitaemia. Delayed-type hypersensitivity (DTH) against SRBC was measured as footpad swelling after sensitisation by the s.c. or i.v. route and intraplantar challenge. DTH reactions were reduced during prepatency in all infections after s.c. sensitisation. During patency, 24-h reactions were similar to those of age-matched controls but the swelling persisted 24 or 48 h longer than in the latter. InA. viteae infections, even enhanced 24-h reactions were found during patency. Histological investigations did not reveal differences in the type of cell infiltrations between infected and control animals. After i.v. sensitisation with SRBC,L. carinii- andA. viteae-infected animals showed weaker DTH reactions than the controls, independent of the period after infection. In the case ofB. malayi infections, DTH reactions were similar to those of controls during early prepatency, whereas reduced DTH responses were observed later than 50 days p.i. As shown inL. carinii-infected animals, depressed DTH reactions after i.v. sensitisation did not depend on an altered expression phase but rather on an altered regulation during the inductive phase of the response: increases in the sensitising SRBC doses that caused decreasing DTH reactions in uninfected animals led to enhanced reactions in infected animals. Phagocytosis of i.v. injected⁵¹Cr-labelled SRBC was enhanced during prepatency inL. carinii infection and during patency in all infections.Dedicated to Prof. Dr. W. Peters on the occasion of his sixtieth birthdaySupported by a DAAD grant     

Delayed-type hypersensitivity toEntamoeba histolytica in mice and hamsters: a comparison

Delayed-type hypersensitivity (DTH) to live or fixedEntamoeba histolytica was induced and compared in mice and hamsters. Peak reactions were obtained 24 h post-challenge. In mice, challenge with 10⁵ amoebae produced maximal, specific footpad swelling; in hamsters, 5×10⁴ were required. Elicitation of DTH in mice was strongest 1 week after induction and remained comparatively high for 8 weeks. In hamsters, elicitability declined after 1–2 weeks. Cyclophosphamide increased footpad reactions in mice and hamsters when given 1 day prior to induction but not prior to challenge. Reactions were usually somewhat (but not significantly) stronger in mice than in hamsters, which was also evident from adoptive transfer experiments. Thus, differences in cell-mediated immunity as expressed by DTH in mice and hamsters do not explain the differential susceptibility of these animals to infection with this parasite. In hamsters, multiple footpad injections of live or fixed amoebae lowered the percentage of subsequent liver infections after i.p. injection of virulent amoebae.     

Immunomodulatory properties of platelet factor 4: prevention of concanavalin A suppressor-induction in vitro and augmentation of an antigen-specific delayed-type hypersensitivity response in vivo.

The immunomodulatory properties of platelet factor 4 (PF4) have been examined in vitro and in vivo. This agent prevented the induction of concanavalin A (Con A)-induced suppressor cells in vitro in a dose-dependent manner but it did not affect the function of established Con A suppressor cells. This effect was not due to an enhanced production of interleukin-2 (IL-2) by lymphocytes exposed to PF4. The delayed-type hypersensitivity (DTH) reaction to sheep erythrocytes (SRBC) was used as a model for the generation of antigen-specific suppression in vivo. PF4 enhanced the magnitude of the swelling following SRBC challenge 10 days after sensitization by the i.p. route or following sensitization by both the s.c. and i.p. routes. These studies show that PF4 has immunomodulatory activities in well-defined models of cell-mediated immunity and suggest that this agent has a potential use in the dissection of events in antigen-specific suppression.     

Use of a skin test assay to determine tumor-specific CD8+ T cell reactivity

We have observed delayed-type hypersensitivity (DTH) reactions in immunized mice challenged subcutaneously with class I-binding peptides related to rejection antigens recognized by cytotoxic T lymphocytes on mutagenized (tum^?) variants of mastocytoma P815. As observed by skin test in virally infected mice challenged with viral peptides, the intrafootpad injection of tum^? peptides resulted in a dose-dependent DTH that peaked at approximately 24 h. The response was mediated by CD8⁺ cells and could be induced by previous vaccination of mice with live tumor cells, intrasplenic deposition of the eliciting peptide, or adoptive transfer with peptide-pulsed syngeneic dendritic cells. These sensitization procedures resulted in an immunologically specific footpad reaction detectable for up to 2–6 months after priming. The evaluation by DTH in cancer patients of long-lived CD8⁺ anti-tumor T cell responses following local challenge with tumor-specific peptides may be of great interest in human immunotherapy trials involving immunization against identified tumor antigens.     

Delayed hypersensitivity to Trypanosoma cruzi in mice: specific suppressor cells in chronic infection.

In mice chronically infected with Trypanosoma cruzi there are antigen-specific suppressor cells which inhibit the development of delayed hypersensitivity (DTH) to T. cruzi antigen but not to an unrelated antigen, keyhole limpet haemocyanin (KLH). This was shown by comparing the 24 hr footpad reactivity, elicited by injection of soluble T. cruzi antigen, of infected mice with that of mice immunized with killed T. cruzi antigen after pretreatment with cyclophosphamide. In the latter, 24 hr footpad swelling represented a DTH reaction in that the cellular infiltrate was predominantly mononuclear and the reactivity could be transferred to normal recipients by lymphoid cells but not by serum. Chronically-infected mice also developed 24 hr footpad swelling but the fact that this was undiminished from an earlier 3 hr reaction and could not be transferred to normal recipients by either local or systemic injection of cells, as well as the histological features, all implied that it represented a prolonged Arthus reaction. The absence or minimal levels of specific DTH detectable in chronic T. cruzi infected mice was accompanied by the presence in their spleens of cells which specifically suppressed the generation of DTH to T. cruzi in normal mice. Suppressor cell activity was radioresistant (10 Gy/1000 rad) and T-cell mediated as defined by significantly decreased and increased suppression following anti-Thy 1.2 serum treatment and nylon wool fractionation, respectively. The ability of chronic T. cruzi mice to develop DTH to an unrelated antigen KLH was unimpaired.     

Suppressive and augmentative effects of recombinant human interleukin-2 upon delayed type of hypersensitivity in the mouse

The in vivo action of recombinant human interleukin-2 (IL-2) was investigated against the delayed type of footpad swelling to sheep red blood cells (SRBC) in B₆D₂F₁ mice. A single intravenous injection of 1×10⁵ of SRBC induced transient cell-mediated immunity for delayed type of hypersensitivity (DTH) which peaked four days after the immunization and diminished rapidly thereafter. IL-2 exerted both suppressive and augmentative effects, depending on the timing of its adminstration in relation to the immunization. Daily intraperitoneal injections of as much as 5× 10⁴ Jurkat units of IL-2 from day 0 through day 3 caused marked suppression of DTH elicited on day 4. On the other hand, three or four consecutive injections of IL-2 from day 4 or day 3 through day 6 produced potent DTH on day 7, when DTH was faint, if there was any, without IL-2 administration. Potentiation of DTH was also observed when three injections of IL-2 were given from day 7 through day 9 and the antigen was challenged on day 10. These results suggest that IL-2 acts as an immunomodulator against cell-mediated immunity to SRBC in the mouse.     

Regulation of delayed-type hypersensitivity. I. T suppressor cells for delayed-type hypersensitivity to sheep erythrocytes in mice.

Mice injected with 1 X 10(8) sheep red blood cells (SRBC) into the footpad showed high levels of delayed-type hypersensitivity (DTH) to SRBC 4-8 days after the injection. In contrast, mice injected intravenously with 1 X 10(9) SRBC were unresponsive to DTH induction through 1 X 10(8) SRBC injected into the footpad. This suppression of DTH was maintained for at least 6 weeks and was transferable spleen, lymph node and thymus cells to normal syngeneic recipients. Bone marrow cells, on the other hand, did not contain the suppressor cells. The suppression of DTH was antigen-specific in that DTH to chicken red blood cells and contact sensitivity to 2,4-dinitrofluorobenzene was not affected. The suppressor cells were theta-positive and Ig-negative. They appeared in the spleen in optimum number 3-4 days after induction. The suppressor cells affected both the induction and manifestation of DTH. The presence of suppressor and effector cells for DTH inducible by different routes of antigenic presentation reflects the dynamic balance in the regulation of DTH.     

Interleukin 6 inhibits delayed-type hypersensitivity and the development of adjuvant arthritis

We studied the effect of interleukin 6 (IL 6) on the delayed-type hypersensitivity (DTH). In mice immunized with sheep red blood cells (SRBC), a DTH response was evoked by antigen challenge into the hind paw 5 days after immunization. The magnitude of the response was assessed by footpad swelling measured 24 h after antigen challenge. IL 6 significantly suppressed the DTH in its induction phase in a dose-dependent manner when administered s.c. into the back at a dose of greater than 2.5 micrograms twice a day (5 micrograms/day) for 5 consecutive days from the day of immunization (day 0) to 1 day before antigen challenge (day 4). Heat-inactivated IL 6 did not suppress the DTH response. Furthermore, the suppressive activity of IL 6 was completely abolished by affinity chromatography on an anti-IL 6 antibody. This suppression was also obtained when IL 6 was administered only on day 0 and day 1, but not on days 3 and 4. This indicates that IL 6 acts on the early part of the induction phase of DTH development. Furthermore, footpad swelling was suppressed even by the administration of IL 6 after antigen challenge. These results show that IL 6 suppresses both the induction and effector phases of DTH. To confirm further this inhibitory effect of IL 6, we examined its effect on the development of adjuvant arthritis in rats. Administration of IL 6 also significantly suppressed the development of adjuvant arthritis.     

Systemic delayed-type hypersensitivity to cholera toxin and a detoxified derivative.

The delayed-type hypersensitivity (DTH) response to cholera toxin (CT) and an immunopurified formalinized toxoid (TD) was studied in adult BALB/c mice. Intradermal injection of CT in non-immune animals produced substantial footpad oedema which interfered with the measurement of specific DTH but TD proved satisfactory as a challenge antigen. DTH to CT was induced by doses ranging from 0.1 to 10 micrograms, in complete Freund's adjuvant (CFA). The optimal reaction was primed for by 1 microgram CT. Doses of TD with an equivalent B subunit content were equally capable of inducing DTH as the holotoxin. The time-course of the footpad swelling revealed that the DTH response was biphasic. Histological examination showed that the initial swelling was due to tissue oedema and the subsequent increase in footpad thickness was associated with a mononuclear cell infiltrate at the site of antigen challenge. Adoptive transfer experiments were used to demonstrate that the DTH was antigen-specific and could be passively transferred by immune effector T cells. This is the first study to demonstrate an effector T cell response to CT. A role for T cell reactions in the intestinal mucosa must now be examined as a potential contributory mechanism in the prevention of choleraic diarrhoea.     

Suppression of the delayed-type hypersensitivity and cell-mediated immune responses to Listeria monocytogenes induced by Pseudomonas aeruginosa.

Pseudomonas aeruginosa-mediated suppression of the immune response to Listeria monocytogenes was investigated in mice. Because delayed-type hypersensitivity (DTH) footpad swelling to L. monocytogenes was suppressed equally in lipopolysaccharide-responsive and -hyporesponsive mouse strains, the lipopolysaccharide component of P. aeruginosa could not have been the suppressive agent. Mucoid P. aeruginosa cells were no more suppressive than their nonmucoid revertants; therefore, mucoid coating was not an additional immunosuppressive element. Interleukin-1 and macrophage inhibitory factor production to L. monocytogenes and clearance of L. monocytogenes from mouse spleens were all decreased by prior Pseudomonas infection, indicating that cell-mediated immunity, as well as DTH, was decreased to a sublethal Listeria dose. The timing of Pseudomonas exposure relative to Listeria sensitization was varied. P. aeruginosa injected 24 or 6 h before or at the same time as L. monocytogenes depressed DTH to Listeria challenge 7 days later. Animals treated in this way could not respond to reinfection with L. monocytogenes at 13 days. P. aeruginosa administered to L. monocytogenes-sensitized mice at the time of footpad challenge was suppressive, but these mice responded normally upon reinfection. It appears that P. aeruginosa induced two types of suppression to L. monocytogenes: a transient suppression, affecting DTH challenge but not resensitization, and a longer lasting suppression that did not permit mice exposed to P. aeruginosa at the time of Listeria sensitization to respond to subsequent Listeria exposure.     

Long-lasting enhancement of the delayed-type hypersensitivity response to heterologous erythrocytes in mice after a single injection of cyclophosphamide.

Previous reports have indicated that cyclophosphamide (CY) treatment can enhance delayed-type hypersensitivity (DTH) reactions by abrogating suppressor T cell functions. Such findings have suggested that cells in the suppressor lineage may be particularly sensitive to this alkylating agent. The experiments reported here demonstrate that a single injection of CY before sensitization can induce a long-lasting state of enhanced DTH responsiveness to sheep red blood cells (SRBC) in mice. This enhancement required concurrent antigenic stimulation and appeared to be antigen-specific. Additionally, CY treatment of sensitized mice before the first antigenic challenge for DTH resulted in suppressed responses to that challenge, followed by enhanced DTH to subsequent challenge with the same antigen. The suppressed response was achieved with a lower dose of CY than the subsequent enhancement and also required concurrent antigenic stimulation. These results indicate that the effects of CY on both effector and suppressor mechanisms are critically dependent upon antigenic stimulation, and suggest that apparent suppressor sensitivity to CY may be a function of differential ability to recover from CY treatment in a context of antigenic stimulation.     

Naive T cells can mediate delayed-type hypersensitivity response in T cell receptor transgenic mice

We produced transgenic mice expressing Tcell receptor-αβ chain genes, derived from the chicken ovalbumin (OVA)-specific I-A^d-restricted CD4⁺CD8^? T helper cell clone 7–3–7. In transgenic mice with H-2^d genetic background (Tg-d mice), delayed-type hypersensitivity (DTH) was induced in the hind footpad by one inoculation with OVA without any previous sensitization, suggesting that naive T cells have the potential to be involved in DTH response. Spleen cells from nonimmunized Tg-d mice showed a strong T cell proliferative response to in vitro stimulation with OVA. Furthermore, these spleen cells produce cytokines including interleukin(IL)-2, IL-3, interferon-γ, granulocyte/macrophage colony-stimulating factor, macrophage inflammatory protein (MIP)-1α and MIP-1β, which may play an important role in the attraction of mononuclear cells to an antigen-challenging site.     

CD8+ cell activation to a major mastocytoma rejection antigen,P815AB: requirement for tum− or helper peptides in priming for skin test reactivity to a P815AB-related peptide

Delayed-type hypersensitivity (DTH) responses, mediated by CD8⁺ cells and detected by skin test assay, occur in sensitized mice in response to challenge with class I-restricted antigenic peptides of mutagenized (tum^?) P815 mastocytoma cells. In contrast, a nonapeptide related to a tumor rejection antigen, P815AB, failed in this study to elicit DTH after sensitization of mice with irradiated tumor cells or adoptive transfer of P815AB-pulsed dendritic cells. Unresponsiveness, however, could be overcome by immunization with tumor cells co-expressing P815AB and tum^? antigens. When used for cell pulsing in vitro, a mixture of P815AB and tum^? peptides was also highly effective in inducing anti-P815AB reactivity, as was the combined use of P815AB and class II-restricted peptides of tetanus toxin or Plasmodium berghei circumsporozoite protein. While the effector phase of the CD8⁺ cell-mediated DTH to P815AB was unaffected by the ablation of CD4⁺ cells, the same treatment, or neutralization of IFN-γ, negated the induction of reactivity if it occurred at the time of sensitization. Thus, defective activation of CD4⁺ cells may contribute to the poor immunogenicity of P815AB. Besides providing an insight into the mechanisms of anti-tumor protection induced by tum^? cells, these data offer useful information for the design of vaccination strategies against identified tumor antigens.     

Peripheral denervation suppresses the late phase of delayed-type hypersensitivity

The impact of peripheral denervation on antigen-specific immune responses was analysed on the B and T cell levels. Delayed-type hypersensitivity (DTH) response to sheep red blood cells (SRBC) or oxazolone was used in mice as a model system of in vivo T cell reactivity. Serum antibody levels to SRBC, measured by an enzyme-linked immunosorbent assay (ELISA), were evaluated to analyse the B cell response. The effect of peripheral denervation on immune responsiveness was studied both at the point of sensitization and elicitation. The results show that peripheral denervation significantly suppresses the local DTH response. The late, inflammatory phase but not the early phase of the DTH reaction was reduced after denervation (p less than 0.01). The DTH suppression by denervation was similar irrespective of whether the neurectomy was performed 1 or 4 weeks prior to sensitisation. Even in the contralateral limb, with intact innervation, the inflammatory DTH reactivity was decreased. We believe that this phenomenon might be due to abrogation of the reflex arch since the denervation procedure did not give rise to a significant systemic downregulation of DTH. Also, peripheral denervation significantly suppressed footpad swelling induced by local administration of cholera toxin, a potent phlogistic compound. The antibody response against the same immunogen was not influenced by denervation. Our results suggest that denervation of a mixed peripheral sensory/motor nerve abrogates the formation of both T cell-dependent and independent inflammatory responses.     

Dextran sulphate: an adjuvant for cell-mediated immune responses.

The effect of high mol. wt dextran sulphate (DS) on cell-mediated immune responses was studied. Three criteria were used to assess cell-mediated delayed-type hypersensitivity: footpad swelling, i.d. skin tests and macrophage migration inhibitory factor (MIF) production. Guinea-pigs sensitized with egg albumin (EA) and treated with DS showed strong positive delayed skin tests. Control animals given only EA showed negative skin tests. Lymphocytes from mice sensitized s.c. with EA and treated with DS showed an increase in MIF production. Delayed footpad swelling responses in mice sensitized s.c. with sheep red blood cells (SRBC) and treated with DS were increased when the mice were challenged 8 days after sensitization. Doses of DS which were effective in increasing delayed footpad swelling ranged from 50-200 mg DS/kg body weight. DS was only capable of increasing delayed footpad swelling responses when both SRBC and DS were injected s.c. at the same site. Intraperitoneal injection of both SRBC and DS obeebction of both s.c. but at different sites did not result in increased delayed footpad swelling. DS was capable of augmenting footpad swelling responses when given s.c. as much as 6 days before SRBC. The optimal time for administration of DS was 2 days before SRBC. Injection of DS 2 days or more after SRBC resulted in no increase in delayed footpad swelling responses. The results of this study indicate that dextran sulphate is a potent adjuvant for cell-mediated delayed-type hypersensitivity immune responses in both mice and guinea-pigs.     

Regulation of delayed-type hypersensitivity V. Suppressor cell memory in antigen-specific suppression of delayed-type hypersensitivity to sheep erythroeytes

Mice primed i. v. with 10⁹ sheep red blood cells (SRBC) produce antigen-specific T suppressor (Ts) cells which inhibit both the induction and the expression of delayed-type hypersensitivity (DTH). These Ts cells are detectable in the spleen and lymph nodes 3–5 days after priming but are largely absent by 6 days. The transient detect-ability of the Ts cells contrasts sharply with the profound antigen-specific suppression which persists in primed donor mice for at least a year. Evidence is presented that this long-term impairment of DTH is maintained, at least in part, by memory Ts cells which are Thy-1⁺, cyclophosphamide-resistant and antigen-specific. Although they appear to be co-induced with the short-lived primary Ts cells and localize initially in the lymphoid organs, they are present in the long-lived circulating pool of T cells and can be adoptively transferred by celomic parabiosis. Memory Ts cells are readily reactivated by lower doses of SRBC which would induce T effector cells rather than Ts cells in naive animals. Reactivated memory Ts cells seem to generate a population of antigen-specific secondary Ts cells which again localizes in the lymphoid organs and can adoptively suppress the induction and expression of DTH to SRBC.     

Genetic control of delayed-type hypersensitivity to D-penicillamine antigen

For determining the mechanism of genetic control of D-penicillamine free-base-specific delayed-type hypersensitivity (DTH) in mice, footpad swelling response was employed. Studies with various congenic and recombinant inbred strains of mice revealed that D-penicillamine free-base-specific DTH was controlled by the I-A subregion. The footpad swelling response showed a highly antigen-specific pattern, and revealed that D-penicillamine free base was not cross-reactive with D-penicillamine disulfide or L-penicillamine, but with D-penicillamine HCl. Treatment of immune lymphoid cells with monoclonal antibodies plus complement revealed that the cells responsible for DTH transfer were Lyt-1+2-, L3T4+ and Ia-T cells.