Different time course patterns of local expression of delayed-type hypersensitivity to sheep red blood cells in mice.

The delayed-type hypersensitivity (DTH) reaction, a peripheral expression of cell-mediated immunity is still a crucial in vivo immunological test. Nevertheless, the biological significance of its time course remains unclear. Thus, an exhaustive study of DTH was undertaken in mice immunized with increasing doses of sheep red blood cells (SRBC) inoculated intravenously (iv) or subcutaneously. The results showed that overall DTH reactions peaked at 18 hr except in mice iv immunized with the lowest doses (10(5) and 10(6)) and elicited at Day 4. The protracted DTH reaction was shown to be associated with an histological picture of tuberculin-type reaction. A part of the 18-hr DTH reaction is mediated by serum in mice inoculated with large doses of SRBC; nevertheless, numeration by limiting dilution analysis of circulating DTH cells showed that the frequency of these cells correlates with the 18-hr DTH level. The protracted DTH shown at 42 and 48 hr, 4 days after immunization with 10(5) and 10(6) SRBC, could not be transferred in naive recipients with immune spleen cells; it was independent of the antigen life span and did not result from immunization modulation at the bone marrow level on recruitable cells.     

Effects of pertussis toxin on delayed-type hypersensitivity responses and on the activity of suppressor T cells on the responses

Experiments were performed on mice to investigate the effects of pertussis toxin (PT) on delayed-type hypersensitivity (DTH) to ovalbumin (OA) and on the activity of suppressor T cells on the DTH (DTH-Ts). Mice immunized with alum-precipitated ovalbumin showed a transient DTH, which was determined as footpad swelling which disappeared 2 weeks after immunization. Maximal footpad swelling was observed 24 hr after DTH elicitation. On the other hand, when mice received PT (2 micrograms/mouse) at the time of immunization, the transient DTH became an enhanced and persistent DTH, which persisted for at least 4 weeks. In addition, the time of maximum footpad swelling was delayed from 24 to 48 hr after DTH elicitation. The immune spleen T cells from PT-treated mice showed a persistently high ability to transfer DTH into syngenic naive mice. DTH-Ts was induced in spleens of mice injected iv with OA-coupled syngeneic spleen cells. However, when these mice received PT at the time of suppressor induction, their spleen cells revealed considerably reduced suppressor activity. The activity of DTH-Ts was also reduced when DTH-Ts were either treated in vitro with PT or transferred into PT-injected recipient mice. From these results, interference with the suppressor function of DTH-Ts from PT was considered to be, at least in part, as an enhancing mechanism of DTH.     

Effect of antiserum against isologous aggregated immunoglobulins on the delayed-type hypersensitivity in mice immunized with sheep red blood cells

The mouse antiserum against isologous aggregated immunoglobulins (MAAS) injected to mice sensitized with 10(5) sheep red blood cells (SRBC) did not influence the delayed-type hypersensitivity (DTH) tested on the peak of sensitization (the 4th day) but enhanced significantly DTH tested on the 6th day. MAAS completely abolished the DTH suppression observed after sensitization with 5 x 10(7) SRBC. In transfer experiments the number of the DTH suppressor cells decreased in the spleen of sensitized mice under the MAAS action. MAAS did not affect the proliferation of antibody-forming cells (AFC) and hemagglutinin production but reduced by 70% the number of rosette-forming cells (RFC) in the spleen on the peak of the initial immune response. The data obtained may indicate that RFC participate in DTH suppression.     

Secondary delayed-type hypersensitivity to sheep red blood cells in mice: a long-lived memory phenomenon

Immunization of mice with sheep red blood cells (SRBC) can induce the capacity to react with a secondary delayed-type hypersensitivity (DTH) immune response upon a booster injection of the antigen. In this paper the kinetics of secondary DTH after intravenous (iv) immunization with various doses of SRBC was studied by means of the foot swelling test. Dose-response studies showed that maximal secondary DTH responsiveness was obtained by iv administration of a priming dose of 3 × 10⁴ SRBC and a booster dose of 3 × 10⁵ SRBC 2 months later. Secondary DTH in such treated mice was characterized by an earlier appearance of the state of DTH, an earlier peak reactivity, and an increased intensity of the DTH response as compared to the primary DTH response. Up to 1 year after priming, a secondary DTH could be elicited, indicating the long-lived character of this memory phenomenon. With increasing intervals between the priming and booster injection, a gradual shift to a later time, of the peak secondary DTH reactivity was found. The capacity of primed mice to react with an increased intensity upon a booster injection could be adoptively transferred into lethally irradiated recipients by means of spleen cells obtained from primed mice. This phenomenon appeared to be highly dependent on Thy 1.2⁺ cells and on the booster dose of SRBC. The DTH reaction, evoked in such recipients, showed a prolonged time course.     

A requirement for helper T cells in the induction of delayed-type hypersensitivity

This paper describes a model system for studying the role of helper T cells in the induction of delayed-type hypersensitivity (DTH). Cyclophosphamide- (CP) treated mice sensitized with antigen 3 days later develop high levels of delayed-type immunity; however, DTH cannot be demonstrated in mice that are sensitized with antigen 1 day after drug treatment. The inability to respond to antigen 1 day after CP treatment can be restored if either normal or low-dose primed spleen cells are transferred at the time of sensitization. Although irradiated (1500 rad) normal spleen cells are unable to restore DTH, such treatment has no effect on the primed spleen cell population. The lymphocytes responsible for restoring the DTH response were identified as T cells, in that treatment with anti-Thy-1.2 serum and C abrogated their effect. Furthermore, restoration of the DTH response was dependent on the presence of antigen at the time of lymphocyte transfer; irradiated primed cells could not transfer DTH alone. The DTH effector cells in reconstituted mice were identified as originating from the host and not from the transferred cell population. This was accomplished by using anti-H-2 serum to identify the source of the DTH effector cells after transferring parental (H-2b) irradiated primed spleen cells into CP-treated F1 mice (H-2b,k). Thus, the irradiated transferred cells are behaving as helper T cells and promoting the development of DTH effector cells in the host.     

Delayed-type hypersensitivity (DTH) in BCG-sensitized mice I. Lack of suppressor T cell activity on DTH to sheep red blood cells.

Mice pretreated with an intravenous (i.v.) injection of BCG (BCG-sensitized mice) and then immunized intravenously with a high dose (10(8)--10(9)) of sheep red blood cells (SRBC) 2 weeks later developed strong delayed-type hypersensitivity (DTH) to SRBC, as in mice pretreated with cyclophosphamide (CY) (CY-treated mice) and then immunized with SRBC 2 days later; normal mice given the same dose of SRBC did not show such DTH. The mechanism of this strong DTH to SRBC which developed in BCG-sensitized mice was studied, by comparing it with that in CY-treated mice. The transfer of either whole spleen cells or thymus cells, but not serum, obtained from mice immunized with i.v. injections of 10(9) SRBC 4 days previously (hyperimmune mice) did not suppress either the induction or the expression of DTH to SRBC in BCG-sensitized mice, but suppressed those in CY-treated mice. The suppressor cells were SRBC-specific T cells. Adoptive transfer of DTH to SRBC by spleen cells from either BCG-sensitized mice of CY-treated mice to hyperimmune recipients failed. The adoptive transfer of DTH from BCG-sensitized mice to normal recipients also failed if the spleen cells from hyperimmune mice were cotransferred. Whole body irradiation (600 rad) of mice 2 hr before or after the time of immunization with SRBC reduced significantly DTH to SRBC in both BCG-sensitized and CY-treated mice. It was noticed that the total number of spleen cells in BCG-sensitized mice was 3--4 times larger than that in CY-treated mice. From these results, we conclude that the entity of effector T cells of DTH to SRBC induced in BCG-sensitized mice and in CY-treated mice was not different in terms of susceptibility to suppressor T cells and irradiation, but that the total numbers of effector T cells generated in these mice differed remarkably, resulting in the above-described different responsiveness to suppressor T cells transferred passively.     

Secondary delayed type hypersensitivity to sheep red blood cells in mice: Dependence on long-lived memory cells

Secondary delayed type hypersensitivity (DTH) to sheep red blood cells (SRBC) in mice is a long-lived memory phenomenon which is characterized by the accelerated reappearance of the state of DTH after a booster injection of the antigen. In this paper the nature of the DTH-related T memory cells accounting for secondary DTH was investigated. Parabiosis of primed and nonprimed mice for a period of 4 weeks resulted in an equally large secondary DTH responsiveness in both partners. This ability was maintained in both members for at least 6 months after termination of the parabiosis. These results indicate that (a) DTH-related T memory cells are potentially circulating cells, and (b) the persistence of these memory cells is not dependent on the presence of the antigen which induced their generation. Subcutaneous (sc) injection of intravenously (iv) primed mice with a small dose of antithymocyte serum before boosting did prevent the development of secondary DTH responsiveness in sc boosted mice, but not in iv boosted mice. Treatment of primed mice with vinblastine or azathioprine did not decrease the capacity of adoptive transfer of secondary DTH by means of spleen cells, but passive transfer of secondary DTH was completely abolished by this treatment. These results suggest that (a) SRBC-induced DTH-related T memory cells are nonproliferating, partially sessile, partially recirculating cells, and (b) these memory cells proliferate before they become DTH-related effector cells.     

Activation of T cells by glutaraldehyde-fixed erythrocyte antigens: radiosensitivity of cells mediating delayed-type hypersensitivity reactions in the mouse.

Mice immunized with glutaraldehyde-fixed sheep red blood cells (G-SRBC) show delayed-type hypersensitivity (DTH) reactions to G-SRBC or SRBC. The specificity of the DTH reaction of mice sensitized with glutaraldehyde-fixed antigens is similar to that found after sensitization with unfixed antigens. The dose-response curve for sensitization by glutaraldehyde-fixed SRBC was very different from the curve for normal SRBC. At low doses, both antigens were effective in sensitizing to show DTH but neither induced an antibody response. However, at high antigen doses, only the glutaraldehyde-fixed antigen was efficient in sensitizing to show DTH and it failed to raise an antibody titer. Spleen cells of mice sensitized with fixed RBC can transfer DTH locally but if the donor cells are irradiated (500 R), the transfer is abrogated. In contrast, the transfer of DTH by spleen cells of mice immunized with unfixed antigen is not affected by 500 R. The transfer of DTH by spleen cells of mice immunized with fixed antigen can be blocked by “in vitro desensitization” while the transfer of DTH by spleen cells from mice primed with normal antigen is resistant to “in vitro desensitization.” These results suggest that immunization of mice with different physical states of the same antigen can result in the activation of antigen-specific T cells which exhibit markedly different properties.     

Immunity to herpes simplex virus type 2. Suppression of virus-induced immune responses in ultraviolet B-irradiated mice

Ultraviolet B irradiation (280 to 320 nm) of mice at the site of intradermal infection with herpes simplex virus type 2 increased the severity of the herpes simplex virus type 2 disease and decreased delayed-type hypersensitivity (DTH) responses to viral antigen. Decrease in DTH resulted from the induction of suppressor T cells, as evidenced by the ability of spleen cells from UV-irradiated mice to inhibit DTH and proliferative responses after adoptive transfer. Lymph node cells from UV-irradiated animals did not transfer suppression. DTH was suppressed at the induction but not the expression phase. Suppressor T cells were Lyt-1+, L3T4+, and their activity was antigen-specific. However, after in vitro culture of spleen cells from UV-irradiated mice with herpes simplex virus type 2 antigen, suppressor activity was mediated by Lyt-2+ cells. Culture supernatants contained soluble nonantigen-specific suppressive factors.     

Studies on the mechanism of the enhancement of delayed-type hypersensitivity by pertussigen

The potentiation of delayed-type hypersensitivity (DTH) reactions by pertussigen, a protein toxin from Bordetella pertussis, has been studied in adoptive transfer assays. Lymph node or spleen cells from mice treated with or without pertussigen at the time of immunization with protein antigens were transferred to naive, syngeneic recipients that were challenged with antigen. Cells from donors treated with pertussigen had the capacity to transfer vigorous, antigen-specific DTH reactions. Cells from immunized donors not given pertussigen transferred little or no DTH. These results indicate that pertussigen is able to augment DTH reactions by potentiating the antigen reactivity of cell populations in lymphoid organs. The phenotype of the effector cells induced by pertussigen was Thy-1 positive, L3T4 positive, and Ly-2 negative. Cells from mice given pertussigen and an irrelevant antigen had no influence on specific DTH responses, suggesting that pertussigen enhances the activity of the antigen-specific cell type mediating DTH. The effect of pertussigen and of immunization on the lymphocyte subpopulations present in the lymph nodes was studied by analysis of suspensions of lymph node cells by flow cytometry. In immunized and in nonimmune mice, pertussigen increased the ratio of Ly-2-negative:Ly-2-positive T cells, and reduced the overall proportion of B cells. In immunized mice, pertussigen induced a much higher proportion of large dividing cells from 5 days after sensitization onwards. The relevance of these changes in lymphocyte behavior to the development of enhanced and prolonged DTH in mice given pertussigen is discussed.     

A new interpretation of the involvement of serotonin in delayed-type hypersensitivity. Serotonin-2 receptor antagonists inhibit contact sensitivity by an effect on T cells

5-HT is a neuromediator and a vasoactive amine released by platelets and murine mast cells at sites of inflammation. A role for 5-HT has been proposed in murine DTH and has been attributed to its 5-HT2R-dependent vasoactive properties. We have tested the hypothesis that the role of 5-HT in DTH is related to an interaction of 5-HT with DTH effector T cells. In vivo treatment of sensitized mice with the 5-HT2R antagonists methysergide or ketanserin inhibited both their capacity to elicit DTH and the ability of their lymphoid cells to transfer DTH. In vitro treatment of lymphoid cells, or of nylon wool-purified T cells from sensitized mice, with 10(-7) to 10(-9) M of the 5-HT2R antagonists methysergide, ketanserin, ritanserin, or LY 53857, followed by three washings, inhibited as strongly their ability to transfer DTH, both systemically or locally. Systemic and local co-transfer experiments of 5-HT2R antagonist-treated and untreated cells indicated that this inhibition was not related to the induction of suppression. 5-HT2R antagonist treatment was nontoxic to T cells; did not affect the in vitro response of T cells to mitogen; selectively inhibited the efferent, but not the afferent limb of DTH; and in the efferent T cell cascade, affected the late-acting (24 h) inflammatory DTH T cells, but not the early-acting, DTH-initiating T cells. 5-HT2R selectivity was suggested by the absence of effect of an alpha-adrenergic R antagonist, and by prevention of the inhibitory effect of a 5-HT2R antagonist by prior incubation with the selective 5-HT2R agonist 1-(2,5-dimethoxy phenyl-4-methyl)-2 aminopropane. In summary, inhibition of DTH effector T cell function appeared sufficient, independently of any vascular effect, to account for the in vivo inhibitory effect of 5-HT2R antagonists on the elicitation of DTH. Our data suggest that late-acting DTH effector T cells might express functional 5-HT2R, and that these receptors might require in vivo activation in order for the T cells to locally produce the inflammatory lymphokine-dependent aspects of DTH.     

Requirement for a bacterial flora before mice generate cells capable of mediating the delayed hypersensitivity reaction to sheep red blood cells.

A delayed-type hypersensitivity (DTH) reaction can be elicited by an injection of 10(8) sheep red blood cells (SRBC) into a rear footpad of conventional (CV) mice previously immunized with small doses of SRBC. In contrast, immunization of germ-free (GF) mice with the same doses of SRBC produced no DTH when immunization was by the intravenous (i.v.) route, and only weak reactions when immunization was by the subcutaneous (footpad) route. Varying the immunizing dose of SRBC, or the time at which DTH was elicited, did not produce a state of DTH responsiveness in i.v. immunized GF mice. However, the transfer of lymphocytes from CV mice, immunized 4 to 5 days previously with SRBC, into GF mice, conferred on GF mice the capacity to express DTH. Although DTH was not readily demonstrable in GF mice immunized with SRBC, they nevertheless produced normal levels of hemagglutinating antibody to SRBC. Finally, it was shown that GF mice could generate a normal DTH response to SRBC if they were first monoassociated with a Gram-negative bacterial flora.     

Regulatory mechanism of delayed-type hypersensitivity in mice. I. Properties of memory cpells and suppressor cells for delayed-type hypersensitivity against ovalbumin.

Delayed-type hypersensitivity (DTH) response in mice induced by sc injection of alum-absorbed ovalbumin (OA) was accelerated and enhanced by priming sc with a low dose of urea-denatured ovalbumin (UD-OA), 2 or more days earlier, whereas it was suppressed by priming sc with a high dose of UD-OA, 0 or more days earlier. The ability in primed mice to accelerate or suppress the DTH response could be transferred antigen specifically into cyclophosphamide (CY)-pretreated recipients or normal recipients by spleen cells from primed mice, but not by the T-cell-depleted spleen cells. Furthermore, the ability of spleen cells to transfer the acceleration or the suppression appeared transiently around 7 or 4 days after priming, although the acceleration or the suppression in donor mice persisted for a much longer time. Pretreatment with CY abolished the suppression of DTH response in high dose-primed mice and resulted in the acceleration of DTH response. These results suggest that the activity of DTH-related memory T cells which accelerate and enhance the response can be inhibited by suppressor T cells for the DTH response.     

Suppression of delayed-type hypersensitivity to oxazolone in whole-body-irradiated mice and protection by WR-2721

The effect of whole-body irradiation on cellular immunity, as measured in vivo by delayed-type hypersensitivity (DTH) to oxazolone (4- ethoxymethylene -2-phenyl- oxazol -5-one), was determined in CD2F1 mice. DTH, determined by changes in ear swelling after challenge with oxazolone, was significantly depressed in irradiated mice (500-900 rad of 60Co) in a dose-dependent fashion when animals were irradiated after sensitization and before challenge with oxazolone. Administration of WR-2721 [S-2-(3-aminopropylamino)ethylphosphorothioic acid] 30 min before irradiation (2 days after sensitization) resulted in protection against suppression of DTH, which was dependent on drug and radiation dose. An effective dose of WR-2721 (200 mg/kg body wt) provided an approximate dose-modifying factor of 1.3. The data suggest that WR-2721 interacts with cells involved in that DTH response (lymphocytes and/or macrophages) and that WR-2721 may be useful in protecting against radiation-induced decrements in cell-mediated immunity.     

Generation of suppressor T cells after local immunization with histocompatibility antigens

Subcutaneous (sc) hind-foot immunization (HFI) of mice with allogeneic spleen cells can induce a state of delayed-type hypersensitivity (DTH) as well as a state of suppression of DTH. This paper deals with the suppression induced by HFI. The state of suppression could be adoptively transferred by spleen cells and lymph node cells between Days 3 and 7 after HFI only. However, in the hind-foot-immunized mice the state of suppression lasted at least 25 days. The suppressor cells expressed the Thy-1+, Lyt-1-2+ phenotype and suppressed DTH antigen-specifically. The suppressor cells, however, also suppressed DTH responses to unrelated third-party alloantigens, provided the latter were administered during the induction of DTH together with the same alloantigens that were used for HFI. The HFI-induced T-suppressor cells suppressed the induction phase of DTH (i.e., the proliferative activity of the draining lymph node cells after secondary sc immunization), but not the expression phase of DTH (i.e., the activity of previously activated DTH effector T cells). H-2D compatibility between the donors of the HFI-induced T-suppressor cells and the recipients was required for the adoptive transfer of suppression. The differences in effect of local immunization versus systemic immunization on the induction and functional activity of T-suppressor cells are discussed.     

Delayed hypersensitivity reaction to transplantation antigens in mice with induced tolerance for allo- and xenografts

The delayed-type hypersensitivity reaction (DTH) in mice tolerant to allo- and xenoantigens has been investigated. To induce tolerance adult mice were thymectomized and given 1 X 10(8) allogeneic or xenogeneic spleen cells and cyclophosphamide (200 mg/kg). Such mice failed to develop DTH to donor antigens, while DTH reaction to foreign allo- and xenoantigens was retained. Spleen cells of mice tolerant to alloantigens significantly suppressed the afferent and efferent DTH phases. The suppression was specific and T-cell-mediated. Spleen cells of mice tolerant to xenoantigens could suppress only the afferent DTH phase. The treatment of cells with anti-T-globulin and complement did not abrogate the suppression. The role of DTH suppressors in the induction and maintenance of transplantation tolerance is discussed.     

Primary and secondary delayed-type hypersensitivity to minor histocompatibility antigens in the mouse.

Immunization of mice with viable allogeneic H-2-compatible spleen cells can induce a persistent state of delayed-type hypersensitivity (DTH) to these alloantigens, as measured with the footpad swelling test. Boosting of such mice, 2–4 months after priming, induced a typical secondary-type DTH reactivity. The capacity of secondary DTH to non-H-2 alloantigens could be adoptively transferred from primed mice into irradiated syngeneic hosts by means of nylon wool-nonadherent, Thy-1.2⁺ spleen cells. Vinblastine treatment of the donor mice did not affect the adoptive DTH responsiveness. These results suggest that a population of long-lived T memory cells contributes to secondary-type DTH responsiveness to non-H-2 alloantigens. The phenomenon of persistent DTH is discussed in the light of these results. The hypothesis is put forward that persistent DTH is dependent on the continuous antigen-driven differentiation of long-lived, recirculating T memory cells into nonrecirculating, functionally short-lived DTH effector cells.     

Evidence for Generation of Suppressor T Cells in Mycobacterium lepraemurium-Infected CBA/J Mice,a Mouse Strain Highly Susceptible to the Infection

Susceptibility to Mycobacterium lepraemurium (MLM) infection markedly differed between two mouse strains, CBA/J and C57BL/6. CBA/J mice showed high susceptibility to MLM infection and developed either very weak or no delayed-type hypersensitivity (DTH) to MLM antigen after the injection of MLM. In contrast, C57BL/6 mice, which were resistant to MLM infection, showed significant DTH reaction to MLM antigen after the injection. Treatment of CBA/J mice with cyclophosphamide (Cy) conferred significant resistance to MLM infection on the CBA/J mice, and the treated mice developed a strong anti-MLM DTH response after the MLM injection. When spleen cells from MLM-infected CBA/J mice were transferred to Cy-treated and MLM-infected syngeneic mice, the anti-MLM DTH reaction of the recipient mice was suppressed. Treatment of the spleen cells to be transferred with anti-Thy-1.2 antibody or anti-I-J^k antiserum plus complement abrogated the suppressive activity. Thus, it is suggested that the high susceptibility of CBA/J mice to MLM infection is due to the generation of Cy-sensitive, I-J^k-positive suppressor T cells after infection with MLM.     

The inhibitory effect of T-2 toxin on tolerance induction of delayed-type hypersensitivity in mice.

Mice injected intravenously with 1 X 10(9) sheep red blood cells (SRBC) showed no delayed-type hypersensitivity (DTH) response to SRBC and were unresponsive to DTH induction by sc injection of an optimal dose of SRBC. However, when treated with T-2 toxin, a mycotoxin, 2 days after the iv injection, mice became to show significant DTH response and to be responsive to the DTH induction by the sc injection. When the spleen cells of the mice receiving the iv injection were transferred to unsensitized syngeneic recipients, the DTH response of the recipients to SRBC was suppressed. However, the suppressor activity of the spleen cells was decreased by T-2 toxin treatment. By the iv injection, cell population of the spleen was increased and that of the thymus decreased. In contrast, by T-2 toxin treatment 2 days after the iv injection, cell population of the spleen was not increased and that of the thymus was markedly decreased. The ratio of theta-bearing cells was increased in the spleen by the iv injection. However, such increase was not observed after the T-2 toxin treatment. The ratio of Ig-bearing cells in the spleen was not changed by the iv injection and the T-2 toxin treatment after the iv injection. T-2 toxin seems to interfere with generation of suppressor cells for the DTH response.     

IFN-gamma production by intrinsic renal cells and bone marrow-derived cells is required for full expression of crescentic glomerulonephritis in mice

The contribution of IFN-gamma from bone marrow (BM) and non-BM-derived cells to glomerular and cutaneous delayed-type hypersensitivity (DTH) was studied in mice. Chimeric IFN-gamma mice (IFN-gamma(+/+) BM chimera), in which IFN-gamma production was restricted to BM-derived cells, were created by transplanting normal C57BL/6 (wild-type (WT)) BM into irradiated IFN-gamma-deficient mice. BM IFN-gamma-deficient chimeric mice (IFN-gamma(-/-) BM chimera) were created by transplanting WT mice with IFN-gamma-deficient BM. WT and sham chimeric mice (WT mice transplanted with WT BM) developed crescentic glomerulonephritis (GN) with features of DTH (including glomerular T cell and macrophage infiltration) in response to an Ag planted in their glomeruli and skin DTH following subdermal Ag challenge. IFN-gamma-deficient mice showed significant protection from crescentic GN and reduced cutaneous DTH. IFN-gamma(+/+) BM chimeric and IFN-gamma(-/-) BM chimeric mice showed similar attenuation of crescentic GN as IFN-gamma-deficient mice, whereas cutaneous DTH was reduced only in IFN-gamma(-/-) BM chimeras. In crescentic GN, IFN-gamma was expressed by tubular cells and occasional glomerular cells and was colocalized with infiltrating CD8(+) T cells, but not with CD4(+) T cells or macrophages. Renal MHC class II expression was reduced in IFN-gamma(+/+) BM chimeric mice and was more severely reduced in IFN-gamma-deficient mice and IFN-gamma(-/-) BM chimeric mice. These studies show that IFN-gamma expression by both BM-derived cells and intrinsic renal cells is required for the development of crescentic GN, but IFN-gamma production by resident cells is not essential for the development of cutaneous DTH.