Alloreactivity and mitogen-induced responses in allogeneic murine bone marrow chimeras

Alloreactive mixed lymphocyte reaction (MLR), mitogen-induced response (MR), and suppressor cells against these responses in murine bone marrow chimeras were examined, to clarify the mechanisms of immunological tolerance and immunodeficiency after bone marrow transplantation (BMT). Between 35 and 70 days after BMT, there was no response of spleen cells from allogeneic chimeras against host (C3H/He) and donor (BALB/c) cells, although responses against third party (C57BL/6) cells were detected, thus indicating that these allogeneic chimeras were immunologically tolerant. The activity of suppressor cells against alloreactive responses was increased 35 to 55 days after BMT, so that these suppressor cells appeared to be related to immunological tolerance. Some of the suppressor cells against alloreactive responses were Thy1+. Among them some were Lyt1+ or Lyt2+, and others were Lyt1+2+. Plastic dish non-adherent cells had slightly weaker suppressor activity than adherent cells. Proliferative responses to Con A, PHA, and PWM were decreased 13 to 15 days after BMT, and gradually increased. The responses to LPS differed from those to the former three mitogens, showing an enhanced response 21 to 25 days after BMT. The increased response to LPS did not appear to be simply due to the increased number of non-T cells in the spleen of allogeneic chimeras. The alloantigen specific suppressor cells may play an important role in the induction and maintenance of immunological tolerance, while the alloantigen nonspecific suppressor cells and suppressor cells against MRs may be related to immunodeficiency after BMT.     

Characterization studies of suppressor cells in murine bone marrow chimaeras.

When BALB/c bone marrow cells were transferred to lethally X-irradiated C3H/He mice either intrasplenically (i.s.) or intravenously (i.v.), suppressor cells were detected by means of MLR coculture assays in the spleen of i.s. and i.v. chimaeras. Some but not all of the suppressor cells expressed a Thy 1.2 antigen, indicating that suppressor cells either sensitive or insensitive to anti-Thy 1.2 antibody plus complement treatment were generated in the spleen of i.s. and i.v. chimaeras. According to the examination of Lyt alloantigen expression on suppressor T cells, Lyt 1+2-, Lyt 1-2+, and Lyt 1+2+ suppressor T cells appeared to be present. The culture supernatants from several T-cell clones showed the suppressor activity against alloreactive MLR. Cell surface markers of these clones were composed of Lyt 1+2-, Lyt 1+2+ and Lyt 1-2+. In addition, since Carrageenan treatment abrogated the suppressor activity of plastic dish adherent cells, we conclude that some of them were composed mainly of macrophages.     

Alteration of the T cell self-specificity repertoire by treatment with anti-Ia antibody during embryonic life

The effect of anti-Ia antibody on the development of murine neonatal self-Ia-reactive T lymphocytes in the thymus was studied. A C57BL/6 (B6) mouse pregnant with (B6 X C3H/He)F1 (B6C3F1) embryos was injected with monoclonal anti-I-Ek (m alpha I-Ek) antibody every other day starting from the 12th day of gestation. The mixed leukocyte culture reaction (MLR) responses of thymocytes from m alpha I-Ek-treated neonatal mice were assayed against adult B6 (H-2b), C3H/H3 (H-2k) or BALB/c (H-2d) splenic stimulator cells. The syngeneic MLR response of m alpha I-Ek-treated B6C3F1 neonatal thymocytes against C3H stimulator cells was augmented compared to that of untreated neonatal thymocytes. Experiments utilizing recombinant inbred strains of mice as well as monoclonal anti-Ia antibody blocking experiments suggested that the antigen(s) responsible for this augmentation of syngeneic MLR resided in the I-Ek molecule. The MLR response against B6 or BALB/c stimulator cells was not influenced by m alpha I-Ek treatment. We speculate that m alpha I-Ek antibody blocked the expression of I-Ek molecules in B6C3F1 embryos and this resulted in the alteration of T cell self-specificity repertoire in the thymus. Our results support the concept that Ia molecules play important roles for the elimination of self-reactive T lymphocyte clones in the thymus.     

Evidence for a new lymphocyte-stimulating determinant (Lsd) detected by alloreactive T cell lines

Three alloreactive T cell clones are described which reveal a new lymphocytestimulating determinant (Lsd) controlled by a gene on chromosome 1 of the mouse but different from and possibly centromeric to Mls. Two clones were originally isolated as anti-H-2^b-specific and showed and retained cross-reactivity to Lsd (clone OD3, BALB/c anti-C57BL/6; clone KB37, B10.BR anti-C57BL/10). The third clone (BD7, C57BL/6 anti-CBA/J) was probably originally directed against Lsd. So far, Lsd is only characterized by stimulation of T cell proliferation, and its physiological function is not yet known.     

In vivo administration of cytokine in allogeneic bone marrow chimeras.

When we analyzed the in vivo efficacy of cytokine administration in murine allogeneic bone marrow chimeras, mitogen-induced responses to ConA, PHA, LPS, or PWM were increased by the in vivo administration of human recombinant granulocyte colony-stimulating factor (rG-CSF), human recombinant interleukin 2 (rIL-2), or WEHI-3B conditioned medium (CM). Furthermore, we found increased alloreactive mixed lymphocyte reactions (MLRs) against donor and/or host type alloantigens in spleen cells from (BALB/c----C3H/He) chimeras, although cytotoxic activity against BALB/c or C3H/He target cells was not detected in spleen cells from these chimeras. Since no significant increase of T cells or Ia positive cells was observed, some functional activation, rather than changes in the cell count, appeared to relate to increase immunoreactivity. An increased IL-2 production in spleen cells from chimeras injected with cytokine was observed shortly after the cessation of cytokine administration. Thereafter, an IL-2 production in these chimeras decreased around 45 days after bone marrow transplantation and then recovered nearly to the control level. An increased IL-2 responsiveness was also observed in spleen cells from these chimeras. These findings suggest that the in vivo administration of rG-CSF as well as rIL-2 or WEHI-3B CM (IL-3) can modulate the immunoreactivity in chimeras via the network of immune systems.     

Characterization of virus-specific cytotoxic T cell clones from allogeneic bone marrow chimeras

We established several H-2-restricted lymphocytic choriomeningitis virus (LCMV)-specific cytotoxic T cell clones from spleens of virus-primed C57BL/6 or C57BL/10 (H-2b) and B10.BR (H-2k) mice and from allogeneic C57BL/10----B10.BR and B10.BR----C57BL/10 bone marrow chimeras. Two T cell clones of H-2b origin and restricted to H-2b, 3 of H-2k origin and restricted to H-2k were compared with two clones each derived from the two types of chimeras. Their surface phenotype was found to be Lyt-2+, L3/T4- and KJ16-133+ (2 of 9). Clones from chimeras expressed bone marrow donor H-2 and are restricted to the recipient H-2. H-2k-restricted clones were all specific for Kk whereas all H-2b-restricted clones were specific for Db. These restriction specificities could be further defined by the blocking activity of various monoclonal anti-H-2 antibodies. Interestingly the anti-H-2Db antibodies blocked the restricted virus-specific killing activity of the clones derived B10.BR----C57BL/10 chimeras much more effectively than the activity of the clones derived from conventional H-2b mice. The various clones differed with respect to their fine specificity for LCMV strains. The 3 clones of conventional B10.BR origin only recognized LCMV-WE but not LCMV-Armstrong, Aggressive or Docile; H-2b-restricted conventional clones recognized target cells infected with all LCMV strains except LCMV-UBC-Docile; the T cell clones from the bone marrow chimeras recognized with one exception all LCMV strains tested.     

A private strain-specific idiotype-like structure discovered on CBA-anti-C57BL/6 T lymphocytes

Using rabbit anti-CBA-anti-C57BL/6 sera, a private strain-specific idiotype-like determinant(s) was detected by cellular radioimmunoassay on activated CBA—anti-C57BL/6 T cells. This structure was not expressed on other activated T lymphocytes: CBA—anti-BALB/c; C3H—anti-C57BL/6; AKR—anti-C57BL/6; A/Sn—anti-C57BL/6; BALB/c-anti-C57BL/6; DBA/2-anti-C57BL/6. It is suggested that the gene(s) coding for the private strain-specific idiotype-like determinant(s) of T-cell antigen-recognizing receptors is not located within the murine H-2 complex.     

Degradation of specificity in cytolytic T lymphocyte clones: Mouse strain dependence and interstrain transfer of nonspecific cytolysis

Limiting-dilution culture of murine Ly-2 T cells with concanavalin A (Con A) and irradiated spleen filler cells produces, with high efficiency, cytolytic T lymphocyte (CTL) clones. With most mouse strains (including CBA and C57BL/6) the specificity of these CTL clones drops after day 6 of culture, so that by day 9 the majority of clones can lyse most murine target cells, whether syngeneic or allogeneic. The rate of specificity degradation and relative target cell preference varies with the mouse strain. Some strains (e.g. BALB/c) do not show this effect and CTL clones remain specific to day 9. Many low natural killer (NK) cell strains (e.g. C57BL/6J.bg) maintain CTL specificity in such cultures, but the correlation between CTL specificity and NK status is not absolute. Growth of BALB/c precursor cells on CBA filler cells leads to specificity degradation in the BALB/c CTL clones; however, the specificity of CBA-derived CTL clones is not maintained by growth on BALB/c fillers. The results suggest that specificity degradation is induced in the developing CTL-clone by factors in the culture environment, perhaps a soluble lymphokine (a differentiation factor) or by an infectious agent (an endogenous mouse virus). Although such CTL specificity loss may render many limiting dilution studies of the CTL specificity repertoire invalid, the problem may be bypassed by an appropriate choice of mouse strain.     

Veto-like down-regulation of T helper cell reactivity in vivo by injection of semi-allogeneic spleen cells.

Injection of semiallogeneic (C57BL/6 X BALB/c) F1 MHC class II expressing spleen cells into C57BL/6 mice leads to a clonal deletion or anergy of recipient CD4+ T helper cells with specificity for the allogeneic MHC class II molecules on the injected cells whereas reactivity against third party allogeneic cells is not influenced. These observations were based on analyses in the recipient mice of proliferating CD4+ T cells in mixed lymphocyte reactions (MLR), limiting dilution (LD) cultures and measurements of IL-2 and IL-3 secretion.     

阻断共刺激通路诱导产生的无能细胞的抗原特异性免疫调节作用

目的：了解联合阻断B7-CD28和CD40-CD154通路诱导产生的小鼠免疫无能细胞的免疫调节特性和表型，以及是否具有抗原特异性。方法：Anti-CD154和anti-CD80单克隆抗体加入BALB／C(夏应细胞)和C3H(刺激细胞)的混合淋巴细胞培养(MLR)体系中诱导产生无能细胞。将无能细胞或对照细胞分别加入新的BALB／C和C3H的MLR体系中观察抑制效果。在反应细胞和刺激细胞／第三方刺激细胞(C57BL/6J)之间的MLR体系中加入无能细胞观察抗原特异性。无能细胞中加入刺激细胞或rmIL-2,观察无能细胞的逆转情况。通过流式细胞仪检测无能细胞的表型。结果：无能细胞对反应细胞和刺激细胞之间的MLR具有抑制作用，且呈剂量依赖关系。无能细胞对于反应细胞和第三方刺激细胞之间的MLR无抑制作用。C3H刺激细胞和rmIL-2共同刺激才能逆转无能细胞的无能状态。无能细胞中CD25^ CD4^ T细胞含量上升，而CD45RB^kwCD4^ 和CD28^-CD8^ T细胞含量无改变。结论：联合阻断B7-CD28和CD40-CD154通路诱导产生的小鼠免疫无能细胞具有抗原特异性的免疫调节功能，可以通过感染性耐受的方式抑制淋巴细胞的增殖。     

静息B细胞体外诱导同种T细胞低反应的实验研究

本文采用体外同种混合淋巴细胞实验系统观察了静息B细胞 (restingBcell)诱导的同种免疫低应答反应。C5 7BL/6小鼠脾细胞经贴壁去除巨噬细胞后 ,用抗Thy 1抗体加补体和Percoll非连续密度梯度离心法分离 ,获得纯化的静息B细胞 ,经FACS检测其表面高表达SmIg (94 88% )和处于细胞分裂的G0 期 (95 79% ) ,并表达H 2Kb(99 5 % )和H 2I Ab(82 42 % ) ,但低表达CD80 /CD86 (分别为 4 2 6 %和 4 16 % )。C5 7BL/6小鼠静息B细胞刺激同种BALB/c小鼠T细胞 (初次MLR)只呈现微弱增殖反应 ,明显低于用LPS活化B细胞或全脾细胞刺激时的反应值。作再次MLR实验时 ,经初次MLR处理的T细胞对C5 7BL/6小鼠脾细胞表现为很弱的应答反应 ,但对无关的第三品系AKR鼠脾细胞却呈现强应答 ,说明这种应答低下具有相对特异性。上述结果提示 ,静息B细胞在MLR系统中不能诱导同种T细胞的充分活化而表现为同种免疫应答的低下。这在同种移植中诱导受体对移植物耐受提供有益的启示。     

MULTIPLE FOREIGN NON-H-2 DETERMINANTS ON THE SURFACE OF A CHEMICALLY-INDUCED MURINE SARCOMA*

By immunizing BALB/c (H-2^d mice against normal tissues from C57BL/6J (H-2^b), C3Hf (H-2^k) and DBA/2 (H-2^d), but not from AKR (H-2^k) strains, resistance was induced to the subsequent challenge of the ‘syngeneic’ methyl-cholanthrene-induced BALB/c sarcoma ST5; lymph node cells from allo-immune BALB/c mice were also able to exert a parallel cytotoxic effect against in vitro cultured ST5 cells. The involvement of foreign H-2 specificities in the observed cross-reactions was ruled out by absorptions of H-2 monospecific sera and by the interallelic combinations used, thus suggesting that non-H-2 histocompatibility antigens were responsible for the above findings. By using the indirect isotopic antiglobulin assay, BALB/c anti-C57BL/6J and anti-C3Hf polyspecific sera were found to bind specifically to cultured ST5 cells. C57BL/6J and C3Hf, but not DBA/2, lymph node cells were able to absorb the anti-ST5 activity of the anti-C57BL/6J serum. These results indicated that ST5 cells expressed on their surface at least two different sets of foreign non-H-2 antigens: one shared by C57BL/6J and C3Hf tissues, and detected by both cell-mediated and serological techniques; the other one belonging to DBA/2 tissues, and revealed mainly at the cell-mediated level.     

异基因骨髓移植小鼠免疫功能缺损机制的探讨

异基因骨髓移植(Allogeneic Bone Marrow Transplantation,ABMT)后,受体的免疫功能长期缺损,是患者术后极易感染死亡的重要原因之一.本文对ABMT小鼠(C57BL/6→BALB/c)免疫功能缺损的机制进行了探讨,发现ABMT小鼠IL-2产生明显受损;其脾细胞与(C57BL/6小鼠脾细胞一起过继转移到致死量照射的BALB/C小鼠体内,能抑制移植物抗宿主病(GVHD)的发生.去除其脾T细胞后,这种抑制作用丧失,ABMT小鼠脾细胞上清中发现一种非特异的抑制因子,能抑制正常小鼠脾细胞产生混合淋巴细胞反应的能力;能抑制正常小鼠的脾细胞产生IL-2;抑制正常小鼠脾细胞毒T淋巴细胞(CTL)的杀伤活性.用抗Thy-1.2单抗和补体去除ABMT小鼠脾T细胞后,其脾细胞培养上(?)的上述抑制活性丧失.这说明ABMT小鼠脾T(?)细胞活性增强是其免疫功能缺损的重要原因之一,它通过释放非特异的抑制因子执行其免疫抑制功能.     

Successful pancreatic allografts in combination with bone marrow transplantation in mice.

We have established a new method for pancreatic allografts in mice by combining pancreatic transplantation with allogeneic bone marrow transplantation. In this approach, we first transplanted bone marrow to induce tolerance to both donor-type and host-type major histocompatibility complex (MHC) determinants. Pancreatic tissue from the same mouse strain as bone marrow donor was then grafted under the renal capsule. Acceptance of the grafts was confirmed by histopathological and immunohistochemical techniques. BALB/c mice reconstituted with C57BL/6J bone marrow cells accepted pancreatic tissue from both bone marrow donor (C57BL/6J)-type and host (BALB/c)-type mice. An immunohistochemical study revealed the presence of functional islets under the renal capsules. Assays for both mixed lymphocyte reaction (MLR) and induction of cytotoxic T lymphocytes indicated that the newly developed T cells are tolerant of both donor (stem cell)-type and host-type MHC determinants. By contrast, the T cells of these chimeras showed a significant responsiveness to third party MHC determinants. These findings suggest that pancreatic allografts combined with bone marrow transplantation may become a viable strategy for the treatment of patients with diabetes or patients who have undergone pancreatectomy.     

Regulatory T cells in thymic epithelium-induced tolerance. I. Suppression of mature peripheral non-tolerant T cells

Athymic mice grafted at birth with allogeneic thymic epithelium (TE) display life-long tolerance to tissue grafts of the TE donor strain, in spite of harboring peripheral T cells capable of rejecting those grafts. Tolerance is maintained in these chimeras by TE-specific regulatory CD4 T cells. We presently address the quantification and the mechanisms of this dominant tolerance process. C57BL/6 mice containing variable but defined numbers of peripheral, resident T cells received cell transfers of graded numbers of peripheral T cells from B6(BALB E10) chimeras (C57BL/6 nude mice grafted with TE from 10-day-old BALB/c embryos), resulting in a series of animals containing a wide range of donor (tolerant) versus host (non-tolerant) T cell chimerism. Increasing the relative representation of donor T cells results in a progressive delay in the rejection of BALB/c skin grafts, life-long tolerance being achieved at a ratio of tolerant and non-tolerant T cell populations of 1. In recipients displaying full tolerance, graftreactive non-tolerant T cells were not deleted, anergized or committed to noninflammatory functions. Thus, sorted host T cells from tolerant recipients readily rejected BALB/c skin grafts upon transfer to immunodeficient animals. Finally, measurements of “helper” and inflammatory activities, as well as interleukin-4 and interferon-γ production, failed to discriminate between T cell populations from tolerant and non-tolerant animals after specific in vitro stimulation. We conclude that: (a) TE-selected regulatory T cells can suppress, in a quantitative manner, in vivo T cell responses against major and minor histocompatibility antigens expressed by the TE and, (b) this suppressive activity neither inactivates mature non-tolerant T cells, nor does it seem to drive their differentiation along noninflammatory pathways.     

Self-priming cell culture system for monitoring genetically-controlled spontaneous cytokine-producing ability in mice

To monitor genetically-controlled cytokine-producing ability in mice in vitro, we developed a high-density cell culture system, which is preferable for inducing CD4⁺ T cell-dependent self-priming responses without any antigenic stimulation. When BALB/c spleen cells were cultured at high density (over 1.0×10⁷ cells/well) in 12-well culture plate, they spontaneously produced cytokines including IFN-γ, IL-2, IL-3, IL-5 and IL-6. The spontaneous cytokine production in this self-priming cell culture (SPCC) system was totally dependent on MHC class II-restricted CD4⁺ T cells. It was demonstrated that Th2-type BALB/c background mice exhibited higher levels of spontaneous cytokine production in SPCC culture compared with Th1-type C57BL/6 mice. Moreover, using BALB/c×C57BL/6 F₁ mice and B10D2 congenic mice, it was demonstrated that highly spontaneous cytokine-producing ability in BALB/c background is genetically dominant and it is controlled by non-MHC genes. Unexpectedly, BALB/c mice spontaneously produced higher levels of IL-2 and IFN-γ than C57BL/6 mice. However, BALB/c mice revealed lower levels of CTL and NK cell-generation in SPCC system compared with C57BL/6 mice. These results suggested that genetically-controlled predisposition of BALB/c mice toward Th2 immunity appeared not to be derived from their poor IFN-γ-producing ability but rather derived from their poor responsiveness to IFN-γ.     

Specific Suppression of MLC and CML by Anti-Idiotypic Antibodies in the Mouse

Rabbit antisera directed against idiotypic determinants of alloreactive mouse CBA anti-C57BL/6 T blasts were raised in the following manner: first, a rabbit serum directed against nonspecific CBA blasts cells was prepared by injecting CBA concanavalin A blasts three times at monthly intervals into a rabbit. Second, specific CBA anti-C57BL/6 T lymphoblasts were induced in a mixed lymphocyte culture (MLC), were purified by gravity sedimentation through a fetal calf serum gradient, and, finally, were incubated with the anti-blast serum from the first step. During this incubation, presumably all epitopes of the blast cell population were blocked by anti-blast antibodies, except for the greatly amplified set of CBA anti-C57BL/6 alloreactive idiotypes. The mixture was then injected into fresh rabbits, which were boosted with similar mixtures after 3 and 6 weeks. Blood samples were removed 10 days after each injection. Such sera, when used together with complement, inhibited specifically the stimulation of CBA cells by C57BL/6 antigens in MLC and the CBA anti-C57BL/6 killer cells.     

Self-priming cell culture system for monitoring genetically-controlled spontaneous cytokine-producing ability in mice

To monitor genetically-controlled cytokine-producing ability in mice in vitro, we developed a high-density cell culture system, which is preferable for inducing CD4+ T cell-dependent self-priming responses without any antigenic stimulation. When BALB/c spleen cells were cultured at high density (over 1.0 x 10(7) cells/well) in 12-well culture plate, they spontaneously produced cytokines including IFN-gamma, IL-2, IL-3, IL-5 and IL-6. The spontaneous cytokine production in this self-priming cell culture (SPCC) system was totally dependent on MHC class II-restricted CD4+ T cells. It was demonstrated that Th2-type BALB/c background mice exhibited higher levels of spontaneous cytokine production in SPCC culture compared with Th1-type C57BL/6 mice. Moreover, using BALB/c x C57BL/6 F1 mice and B10D2 congenic mice, it was demonstrated that highly spontaneous cytokine-producing ability in BALB/c background is genetically dominant and it is controlled by non-MHC genes. Unexpectedly, BALB/c mice spontaneously produced higher levels of IL-2 and IFN-gamma than C57BL/6 mice. However, BALB/c mice revealed lower levels of CTL and NK cell-generation in SPCC system compared with C57BL/6 mice. These results suggested that genetically-controlled predisposition of BALB/c mice toward Th2 immunity appeared not to be derived from their poor IFN-gamma-producing ability but rather derived from their poor responsiveness to IFN-gamma.     

Protective efficacy of a 62-kilodalton antigen, HIS-62, from the cell wall and cell membrane of Histoplasma capsulatum yeast cells.

We reported previously that a detergent extract of the cell wall and cell membrane of Histoplasma capsulatum yeast cells contains antigens recognized by T cells. In T-cell immunoblot analysis, a region encompassing 62 kDa was stimulatory for an H. capsulatum-reactive T-cell line and T-cell clones derived from C57BL/6 mice. In this study, we isolated a 62-kDa band, termed HIS-62, from electrophoresed cell wall and cell membrane of H. capsulatum yeast cells and examined its antigenicity and immunogenicity. C57BL/6, BALB/c, and CBA/J mice that were immunized with viable H. capsulatum yeast cells mounted a delayed-type hypersensitivity response to HIS-62 that was stronger than that of normal controls. Spleen cells from each strain of mouse immunized with viable yeast cells proliferated vigorously in response to HIS-62; conversely, splenocytes from control animals did not recognize this antigen. A T-cell line and 5 of 5 T-cell clones from C57BL/6 mice, 10 of 15 BALB/c T-cell hybridomas, and 8 of 12 CBA/J T-cell hybridomas recognized HIS-62. A cutaneous delayed-type hypersensitivity response to the antigen was apparent in each strain of mouse that was injected with 80 micrograms of HIS-62 mixed with Freund adjuvant. In addition, spleen cells from HIS-62-immunized mice proliferated in vitro in response to this antigen. Vaccination of each strain of mouse with 80 micrograms of HIS-62 conferred protection against a lethal intravenous challenge with H. capsulatum yeast cells. Thus, HIS-62 appears to be an important target of the cellular immune response to H. capsulatum and induces a protective immune response in mice.     

The role of macrophage activation and of Bcg-encoded macrophage function(s) in the control of Mycobacterium avium infection in mice.

Following the intraperitoneal inoculation of 2.5 x 10(8) colony-forming units of Mycobacterium avium strain ATCC 25291, there was bacillary growth in the liver, spleen and peritoneal cavity of C57BL/6, C57BL/10, DBA/1 and BALB/c mice whereas DBA/2, C3H/He, CBA/Ca and CD-1 mice controlled the infection showing constant or slightly decreasing numbers of viable bacteria in the liver and spleen and effective clearance of the bacilli from the peritoneal cavities. The acquisition of non-specific resistance (NSR) to Listeria monocytogenes during the infection by M. avium was high in C57BL/6, BALB/c and C3H/He mice and negligible in DBA/2 and CD-1 mice. The magnitude of the acquisition of NSR was reduced in T cell-deficient mice and was directly proportional to the dose of the inoculum of M. avium. The production of hydrogen peroxide by phorbol myristate acetate-stimulated peritoneal macrophages of M. avium-infected mice was higher in C57BL/6 and BALB/c mice than in CD-1, DBA/2 and C3H/He animals. BALB/c. Bcgr (C.D2) mice, unlike their congenic strain BALB/c, restricted bacterial growth following the intravenous inoculation of 2.5 x 10(8) CFU of M. avium as efficiently as DBA/2 mice. C.D2 and BALB/c peritoneal macrophages from infected mice produced similar amounts of H2O2 but BALB/c mice developed higher levels of NSR to listeria than C.D2 mice. The production of nitrite by peritoneal macrophages from infected mice was found to be enhanced in DBA/2 and C3H/He but not in BALB/c, C57BL/6, DC-1 and C.D2 mice. Resident peritoneal macrophages from C.D2 mice were more bacteriostatic in vitro for M. avium than macrophages from BALB/c mice. The same relative differences between the two macrophage populations were observed when the cells were activated with lymphokines. The results show that the populations were observed when the cells were activated with lymphokines. The results show that the resistance to M. avium infection in mice is under the control of the Bcg gene and that susceptibility may be due to some defect in macrophage antibacterial function not completely overcome by the activation of this phagocyte in the susceptible strains of mice.