The effect of aging on the induction of humoral and cellular immunity and tolerance in two long-lived mouse strains.

Aging is a complex process that adversely affects most if not all components of the immune system. In this report, two long-lived mouse strains have been compared in ability to generate both antigen-specific immunity and tolerance. Although CBA/CaJ mice produced high levels of antibody following injection of aqueous preparations of aggregated human gamma-globulin (AHGG), C57BL/6 mice made only meager antibody responses to such preparations. Age dramatically affects the humoral anti-HGG response to aqueous AHGG in both strains, but the meager response of young C57BL/6 mice was at insignificant levels in aged C57BL/6 mice. Conversely, both mouse strains generated good responses following injection of HGG in complete Freund's adjuvant at both the T and B cell level as evidenced by in vitro antigen-specific T cell proliferation and anti-HGG antibody production. Aged mice of both strains showed a marked decrease in the production of serum anti-HGG antibody in comparison to young mice. Although the antigen-specific T cell proliferative response was significantly decreased in aged CBA/CaJ mice, such proliferation was not affected in aged mice of the C57BL/6 strain. Removal of CD8+ cells from lymph node T cells of either young or aged C57BL/6 mice did not increase the antigen-specific proliferative response, suggesting that loss of CD8+ suppressors during the aging process is not responsible for the high level of antigen-specific T cell proliferation in aged C57BL/6 mice. Tolerance to HGG was readily induced in both young and aged C57BL/6 and CBA/CaJ mice although aged mice demonstrate a modest resistance to tolerance induction when compared to their young counterparts. This resistance was observed in both antibody production and antigen-specific T cell proliferation.     

Selective improvement of thymus and some T cell dysfunctions in NZB mice by in utero thymulin treatment

NZB mice were treated during gestation with thymulin, a thymus-secreted, zinc-associated nonapeptide. Control pregnant NZB mice received either zinc alone or saline alone. Offspring from all three groups of NZB mothers, and age-matched DBA/2 mice, were tested for the following immunologic parameters: thymulin serum levels at 2 and 5 wk of age; splenic anti-sheep red blood cell (anti-SRBC) plaque-forming cell (PFC) numbers after immunization at birth or at 2 wk of age; anti-human gamma-globulin (anti-HGG) antibody titers after immunization at 2 wk of age, with or without prior tolerance induction at birth with deaggregated HGG; spontaneous IgM serum levels at 2 and 5 wk of age; spontaneous splenic anti-trinitrophenyl (anti-TNP) PFC numbers at 2 wk of age. As compared with DBA/2 mice, young NZB mice exhibited low circulating thymulin titers, high antibody responses to SRBC and to HGG, resistance to tolerance induction by deaggregated HGG, increased spontaneous IgM serum levels, and increased spontaneous anti-TNP PFC numbers. However, marked reductions in anti-SRBC and anti-HGG antibody production, both thymus-dependent responses, were observed in the young NZB offspring of thymulin-treated mothers as compared with NZB controls born from zinc- or saline-treated mothers. A delay in the postnatal decrease of serum thymulin levels was also noted in the offspring of thymulin-treated mothers. Interestingly, these effects of in utero thymulin treatment tended to become more pronounced with advancing age during the postnatal period. Conversely, IgM serum levels, spontaneous anti-TNP PFC and sensitivity to tolerance induction were not affected by thymulin treatment during fetal life. Taken together, the data suggest that in utero exposure to pharmacologic concentrations of thymulin induces a persistent and selective improvement of some thymus and T cell dysfunctions but has no effect on intrinsic B cell abnormalities of NZB mice.     

Immunologic tolerance to HGG in mice. I. Suppression of the HGG response in normal mice with spleen cells or a spleen cell lysate from tolerant mice.

Adoptive transfer of spleen cells or spleen cell lysates from mice tolerant to human-gamma-globulin (HGG) specifically suppressed the response of normal syngeneic recipients to HGG. The suppressive activity could be transferred for over 100 days after tolerance induction. The suppression induced by both spleen cells and spleen cell lysate was found to be specific as evidenced by a normal response to a challenge with turkey-gamma-globulin or goat erythrocytes. The activity of the suppressive lysate could be removed by passing the material through an HGG immunoadsorbent column but not by passing it through an anti-HGG column or a BSA column. These results indicated that the factor had antigen specificity and was probably not antigen-antibody complexes. That this suppression was not due to a shifting of the kinetics of the antibody response has also been demonstrated. The antigen-specific suppressor factor in the tolerant spleen cell lysates was a protein with a m.w. of approximately 45,000 daltons. The kinetics of the appearance of both suppressor cells and suppressor factor were consistent with a mechanism of active suppression functioning in the maintenance of tolerance to HGG.     

B cell presentation of a tolerogenic signal to Th clones.

Lightly irradiated (950 R) splenic B cells were inefficient, in comparison to unseparated spleen cells, in stimulating antigen-specific proliferation of Th1 clones specific for human gamma globulin (HGG). This inefficiency was due to antigen-specific inactivation: Th1 clones preincubated with HGG and lightly irradiated B cells or mitomycin C-treated B cells were unable to proliferate to HGG in secondary cultures. In contrast to Th1 clones, Th2 clones proliferated well in response to B cell APC, and showed no decrease in their subsequent antigen-induced proliferative capacity after exposure to lightly irradiated B cells and HGG. However, preincubation of Th2 with lightly irradiated B cells and HGG did inactivate the capacity of Th2 to provide help for antibody production in secondary cultures. These results suggest that under certain conditions B cells may present antigen to Th1 and Th2 cells in a tolerogenic rather than an immunogenic manner.     

Characterization of light chain and light chain constant region fragment mRNAs in MPC 11 mouse myeloma cells and variants

Cultured MPC 11 mouse myeloma cells synthesize not only γ_2b heavy and κ light chains but also a carboxyl terminal (constant region) fragment of κ light chain. In vitro translational analysis of total cytoplasmic and microsomal RNA indicates that these cells contain RNA which directs synthesis of both a light chain precursor and a light chain fragment precursor. Variant clones which do not synthesize either heavy or light chains continue to synthesize the light chain fragment. One such “nonproducing” variant was studied in detail. It does not contain translatable mRNA for the intact light chain but does contain RNA which is translated into the light chain fragment precursor. Nucleic acid hybridization analysis with a cDNA probe specific for the constant region of κ light chains revealed that microsomal RNA from the wild-type cell contains both a 14S and a 10S species of κ specific RNA, whereas the variant contains only the 10S species. Translational analysis of these same RNAs indicates that the 14S species codes for the light chain precursor, while the 10S RNA codes for the light chain fragment precursor.     

Plasmodium yoelii: the thymus-dependent lymphocyte in mice immunodepressed by malaria

Euthymic mice, athymic nude mice, and mice treated with antithymocyte serum were infected with Plasmodium yoelii and immunized 10 days postinfection with pneumococcal polysaccharide (SSSIII). As a control, uninfected mice were also immunized with SSSIII. Splenic plaque-forming cells as well as serum antibody titers to SSSIII were measured 5 days after immunization. In infected euthymic mice, both plaque-forming cells (PFC) and serum antibody were severely depressed. In contrast, plaque-forming cells and serum antibody were approximately normal in infected nude mice and in infected mice treated with antithymocyte serum. Splenic adherent cells from infected euthymic mice failed to function as accessory cells in the in vitro antibody response to a second antigen, the sheep erythrocyte. Moreover, they lacked suppressor activity when cultured with spleen cells from uninfected mice. In contrast, adherent spleen cells from infected mice treated with antithymocyte serum displayed accessory cell function.     

B cells as antigen-presenting cells: antibody production in vitro against a T-dependent antigen

It was examined whether B cells can serve as antigen-presenting cells (APC) in the antibody response to a T-dependent antigen, trinitrophenyl-ovalbumin (TNP-OVA). B cells purified from mice primed with TNP (TNP-B cells) responded to TNP-OVA in the presence of purified T cells sensitized with OVA (OVA-T cells). OVA-T cells required the addition of APC to proliferate in response to TNP-OVA. APC activity of TNP-B cells in the T-cell proliferation was abolished by 4000 R irradiation. Our experiments also revealed that an antibody response requires more adherent cells than the T-cell proliferation. These results indicate that adherent cells possibly accompanying the T- and B-cell preparations were at a less than functional level. There was genetic restriction between T and B cells for the antibody response. B cells in the pellet fraction of 70% Percoll density sedimentation behaved similarly to the unfractionated TNP-B cells in the antibody response. A T-cell clone specific for human gamma-globulin (HGG) also induced an anti-TNP antibody response in B cells from unprimed mice in the presence of TNP-HGG. These results suggest that B cells are able to elicit an antibody response to a T-dependent antigen in the presence of carrier-primed T cells without the participation of macrophages.     

Specific suppression of the immune response by a factor obtained from spleen cells of mice tolerant to human gamma-globulin.

An antigen-specific suppressive factor was extracted from spleen cells of mice made tolerant by injection of deaggregated human gamma-globulin (HGG). The active material could be prepared from T cells, obtained by passaging spleen cells through an anti-immunoglobulin column, although not from cells adherent to the column nor from spleen cells pretreated with anti-Thy-1 serum and C. This factor was antigen-specific since it was retained on immunoadsorbents containing HGG, but not on columns coated with antibody to HGG or with irrelevant antigens. Despite its specificity for antigen it did not bear any classical immunoglobulin determinants. Its m.w. ranged between 30,000 and 55,000 daltons. It was a product of the I region of the major histocompatibility complex since it carried Ia determinants. The properties of this factor are very similar to those reported elsewhere for suppressive factors obtained from primed T cells, cells from nonresponder mice, and allotype-specific cells. This suggest the existence of a major class of immunoregulatory molecules, nonimmunoglobulin in nature, and responsible for the mediation of antigen-specific T cell-dependent suppression.     

The role of hapten-reactive T lymphocytes in the induction of autoimmunity in mice. I. Establishment of the experimental conditions for the termination of immunological tolerance to human gamma globulin.

In order to study the role of hapten-reactive helper T cells in the induction of autoimmunity in mice, an attempt was made to establish an experimental model for the development of hapten-reactive helper T cells and the termination of immunological tolerance against heterologous proteins. Spleen cells taken from mice which were immunized with hapten-isologous protein conjugates (PAB-MGG) demonstrated helper activity for the anti-DNP antibody response of DNP-primed B cells responding to DNP and PAB-conjugated protein, but spleen cells from hapten-heterologous protein conjugate (PAB-HGG)-primed mice could not respond to PAB-determinant. Thus, hapten-reactive helper T cells can develop in mice by the immunization with hapten-isologous protein conjugate, but not with hapten-heterologous protein conjugate. However, spleen cells from mice which had been rendered tolerant by treatment with 2.5 or 0.2 mg of DHGG and then immunized with PAB-HGG could demonstrate helper activity responding to PAB-determinant. This helper activity was PAB-specific, because these spleen cells did not demonstrate helper activity if PAB-determinant was omitted in the primary and the secondary antigen. This helper activity was abrogated by the treatment of spleen cells with anti-θ serum and complement. Thus, hapten-reactive helper T cells were successfully induced by the challenge with hapten-heterologous protein conjugate in carrier-protein tolerant mice. When mice were treated with 2.5 or 0.2 mg of DHGG, no anti-HGG antibody response was induced by the challenge with HGG or PAB-HGG. However, the termination of HGG-tolerance was demonstrated only when the mice were preimmunized with PAB-MGG to raise PAB-rcactive helper T cells, treated with 0.2 mg of DHGG, and then challenged with PAB-HGG. This termination of immunological tolerance was not observed when the mice were preimmunized with PAB-BαA to raise PAB-specific B cells and anti-PAB antibody, or when the mice were treated with 2.5 mg of DHGG. Thus, if HGG-specific B cells remain intact in mice such as treated with low dose of DHGG, these B cells can be activated by some bypass mechanisms in the presence of PAB-reactive helper T cells through the PAB-determinant even in the absence of HGG-reactive helper T cells. These data clearly showed the role of hapten-reactive helper T cells in the termination of immunological tolerance and provide experimental supports to the hypothesis on the termination mechanism proposed by Weigle. The cellular mechanism for the development of hapten-reactive helper T cells in tolerant animals and the cellular mechanism of autoantibody production were discussed on the basis of T-B cell collaboration.     

Immunologic unresponsiveness after gastric administration of human gamma-globulin: antigen requirements and cellular parameters

Gastric administration of human gamma-globulin (HGG) into adult A/J mice leads to the establishment of an antigen-specific unresponsive state to subsequent parenteral challenge with HGG. An unresponsive state is induced in both helper T and B lymphocyte populations. Unresponsiveness in helper T cells is of longer duration than in B cells, lasting at least 9 wk after intragastric intubation. Adoptive cell transfer of spleen cells from gastrically inoculated mice into healthy irradiated, syngeneic recipients revealed that the unresponsive state is stable upon cell transfer and that suppressor cells are present in the spleens of gastrically tolerized mice. The establishment of HGG-specific unresponsiveness is dependent upon both the dose and the form of the antigen adminstered. Soluble and deaggregated HGG are both more efficient than is heat-aggregated HGG in inducing unresponsiveness gastrically. The administered HGG is rapidly eliminated from the animal and only a small fraction reaches the circulation as immunoreactive protein. Although the cellular parameters of the systemic unresponsiveness induced by intragastric intubation with HGG appear similar to the parameters of parenterally induced unresponsiveness, the precise mechanisms by which gastric unresponsive states are established remain to be resolved.     

Antibodies generated from human immunoglobulin miniloci in transgenic mice.

One approach to the production of human monoclonal antibodies focusses on the creation of transgenic mice bearing human immunoglobulin gene miniloci. Whilst such loci undergo lymphoid-specific gene rearrangement, only a small proportion of mouse B cells express the human immunoglobulin chains; the miniloci thus contribute poorly to serum immunoglobulin. Attributing this poor performance to competition between the transgenic and endogenous immunoglobulin loci, we crossed mice bearing a human immunoglobulin heavy-chain (HulgH) minilocus with animals that had been rendered B cell-deficient by disruption of their endogenous heavy-chain locus. The results were dramatic: the human minilocus rescued B cell differentiation such that effectively all B cells now expressed human mu chains. The concentration of antibody in the mouse serum recognised by anti-human mu increased to a concentration about one sixth that in human serum. The HulgH antibodies are heterogenous with diversity being generated by both combinatorial and junctional processes. Following antigen challenge, specific antibody is elicited but at low titre.     

Enhancement of the in vivo antibody response by an 8-derivatized guanine nucleoside

The capacity of the C8-substituted guanine ribonucleosides to enhance the in vivo humoral immune response to the protein antigen, human gamma globulin (HGG), in A/J mice was evaluated. It has been shown recently that the C8-substituted guanine ribonucleosides are a new class of potent adjuvant for humoral immune responses to the sheep erythrocyte antigen. The current studies extend these findings to HGG with 8-bromoguanosine (8BrGuo), a representative of this group of nucleosides. The adjuvant activity of 8BrGuo in this system is highly dose and time dependent. Although 8BrGuo enhanced responses when injected either early (Day 0) or late (Day 4 or 5) after immunization, its administration on Day 1 or 2 most often led to no enhancement, suggesting that 8BrGuo may act on two events separated by a resistant stage in an ongoing immune response. The plaque-forming cell (PFC) response to HGG was enhanced optimally at doses as low as 1 mg 8BrGuo/mouse administered either on the day of immunization or 4 days thereafter. In contrast, however, serum anti-HGG antibody concentration assayed by enzyme-linked immunosorbent assay (ELISA) was enhanced only at doses of 10 mg or more, injected on the day of immunization, but doses as low as 1 mg were effective on Day 4. 8BrGuo was also an effective adjuvant when injected after antigen administration in incomplete Freund's adjuvant or when administered by several different routes (intraperitoneal, subcutaneous, oral).     

Th1 and Th2 clones differ in their response to a tolerogenic signal.

Th1 and Th2 clones specific for human gamma globulin (HGG) were compared and shown to differ in terms of the effects of tolerance induction on Ag-induced proliferation and helper activity. In developing a method to induce tolerance, splenic APC that had been pulsed with HGG and then fixed with 0.15% paraformaldehyde (HGG-FAPC) were used as a means to present Ag to the Th clones in the absence of costimulatory signals. Both Th1 and Th2 clones recognized HGG-FAPC as evidenced by their ability to proliferate to HGG-FAPC. Unlike Th2, Th1 proliferated to HGG-FAPC only in the presence of T cell-depleted allogeneic spleen cells as a source of accessory cell signals. The inability of Th1 cells to proliferate in the absence of costimulatory signals was due to Ag-specific inactivation: Th1 clones preincubated with HGG-FAPC were unable to proliferate when recultured with HGG and irradiated APC. In contrast to Th1 clones, Th2 clones showed no decrease in their Ag-induced proliferative capacity after exposure to any concentration of HGG-FAPC. However, when examined by using a second assay system, that of providing help for anti-HGG antibody production by primed B cells, Th2 preincubated with HGG-FAPC were markedly inhibited (up to 90%) in their ability to provide help. Preincubation with HGG-FAPC also inhibited the helper activity of the one Th1 clone that was found to induce a significant secondary antibody response. Taken together, the results suggest that exposure of Th1 to tolerogen in the form of HGG-pulsed fixed APC inactivates Th1 proliferative capacity, and possibly Th1 helper activity as well. Exposure of Th2 cells to a tolerogen suppresses the mechanism by which the Th2 cells provide Ag-induced B cell help, but does not inhibit the mechanism by which they proliferate to HGG. Furthermore, the results define a model that incorporates Ag processing as well as Ag presentation in the induction of tolerance in vitro.     

Nonspecific enhancement of mouse antihapten IgE antibody response: Involvement of a T-cell subpopulation and its product for the potentiation

A concomitant administration of Nippostrongylus brasiliensis saline extract (Nb) with dinitrophenylated ovalbumin (DNP-Ov) significantly enhanced the anti-DNP IgE antibody response in mice which had been irradiated and given a combination of spleen and mesenteric lymph node cells from syngeneic, infected donors and cells from DNP-keyhole limpet hemocyanin (DNP-KLH)-primed donors. The treatment of lymphocytes from infected mice with anti-mouse brain-associated θ serum and C abrogated the enhancing activity. The potentiation occurred in mice receiving nylon wool-nonadherent cells but not in mice receiving adherent cells. Challenge with Nb plus DNP-Ov failed to induce potentiation in C3H mice which are known as nonresponders to low doses of Ov, whereas challenge with Nb plus DNP-bovine gamma globulin (BGG) potentiated the response. However, further increase of the enhanced response was not obtained by adding carrier (BGG or Ov)-primed cells to the transferred lymphocyte populations. When a T-independent antigen, DNP-Ficoll, was used for challenge concomitantly with antigen Nb, no potentiation occurred, even though DNP-Ficoll did not give any tolerogenic or suppressive effect on the IgE antibody response to DNP-Nb. An enhancing activity on the IgE class of antibody response but not on the IgG class was observed in supernatants of in vitro culture of lymphocytes from infected mice upon stimulation of the cells with 10 to 50 μg Nb. These results indicate that the potentiation is mediated by Nb specific T cells via a soluble factor(s) that enhances specifically the IgE class of antibody responses but nonspecifically in terms of antigens used for immunization. The results also suggest that the potentiating factor displays its activity in the presence of other T cells reactive to carrier determinants of the challenging antigen but not of cells which already have committed themselves to the carrier and differentiated as helper cells.     

The induction of peripheral T cell unresponsiveness in adult mice by monomeric human gamma-globulin

Monomeric human gamma-globulin (HGG), when injected into adult mice, induces a state of specific immunologic unresponsiveness to further challenge with immunogenic forms of HGG. In this report we have directly determined the role of the thymus in the induction of HGG tolerance and the proliferative responsiveness of T cells from normal and HGG-tolerant mice. Draining lymph node T cells were isolated from HGG-tolerized and -challenged mice, and tested for their proliferative response to HGG in vitro. T cells from untreated but challenged adult CBA/CaJ and A/J mice proliferate in response to HGG, whereas such mice given monomeric HGG before challenge fail to show an HGG-specific proliferative response. APC from tolerant or nontolerant mice were equally effective in the support of Ag-specific proliferation of primed T cells. The influence of the thymus gland on HGG-induced T cell unresponsiveness was assessed by determining whether thymectomized mice could be tolerized to HGG. The results suggest that the generation of T cell tolerance to HGG is independent of thymic function as assayed by both antibody production in vivo and T cell proliferation in vitro. Unresponsiveness of T cells from tolerant mice was not a result of the presence of CD8+ cells since removal of CD8+ cells from lymph node T cells did not alter unresponsiveness to HGG in vitro. Further, mixing tolerant T cells with normal HGG-primed T lymphocytes did not inhibit proliferation of the HGG-primed cells. The results of this investigation suggest that this mouse model of tolerance to HGG represents a thymus-independent unresponsiveness of mature peripheral T cells to a nonself-Ag. Understanding the regulation of tolerance to HGG may give additional insight into the mechanisms required for the maintenance and possibly the induction of tolerance to certain self-Ag in peripheral lymphoid organs.     

Specific, transient suppression of the immune response by HGG tolerant spleen cells. II. Effector cells and target cells.

In a previous report, it was shown that spleen cells from mice made tolerant to human gamma-globulin (HGG)5 could specifically inhibit the immune response of normal spleen cells after adoptive transfer to lethally irradiated recipients. However, that report also showed that the suppressive activity was only transiently associated with tolerant spleen cell populations. It was concluded from those experiments that while suppressive activity could be demonstrated in tolerant spleen cells under certain conditions, such activity was not obligatory for the maintainance of the tolerant state. The experiments presented here were performed to determine the nature of the effector cell(s) and the target cell(s) involved in this system of suppression of the immune response. Treatment of cells from tolerant animals with anti-thymocyte serum and complement to remove thymus-derived (T) cells completely abrogated suppresive activity. Removal of adherent cells from tolerant spleen cells by passage over glass wool columns resulted in partial loss of the suppression. The inhibitory activity of the suppressor cells was resistant to 900 R irradiation regardless of whether the tolerant spleen cells were irradiated before or after adoptive transfer. The cellular target(s) for the supprssor cells was examined by using lipopolysaccharide (LPS) as an alternative source of helper activity for the response to HGG. LPS, injected at the time of the initial antigenic challenge of mice that had been reconstituted with tolerant and normal spleen cells, prevented the expression of suppression against bone marrow-derived (B) cells. However, when LPS was presented only at the time of secondary antigenic challenge, it was unable to overcome suppression of the immune response of reconstituted recipients. Thus, LPS could produce a state where the B cells were resistant to suppression, but LPS could not rescue the responsiveness of B cells once the cells in the reconstituted recipient had been suppressed. In addition, the immune response to both the hapten dinitrophenol (DNP) and the carrier (HGG) were suppressed when recipients of tolerant and normal spleen cells were challenged with DNP6HGG. This indicates that T helper cells are also a target for suppression. The results presented in this paper are discussed in relation to a possible mechanism of suppression which proposes that suppressive activity represents the induction of tolerance in immunologically competent cells by HCG which is closely associated with the tolerant spleen cells.     

Nude mice injected with DNA released by antigen stimulated human tlymphocytes produce specific antibodies expressing human characteristics

Nude mice were injected with DNA purified from the nucleoprotein complex released by T lymphocytes previously exposed in vitro to inactivated herpes or poliovirus. After five days the serum of these mice was tested for its virus neutralizing activity. Results show that injected nude mice synthesize antiherpetic or antipolio antibodies depending on the antigen used to sensitize the T lymphocytes in vitro. These antibodies were not found in the serum of uninjected control mice or mice injected with inactivated herpes or polio viruses. Mice injected with DNA release by human T cells produced antibodies carrying human allotypes since they could be neutralized by anti-allotype sera. Moreover their antiviral activity was inhibited by anti-human IgM or IgG. However, the mice which were injected with DNA released by antigen stimulated murine T lymphocytes produced antiviral antibodies which were not neutralized by anti-human allotype sera.     

Whole body irradiation induces IFN-gamma production in BALB/c mice by preventing the appearance of a V alpha 14(+)NK T downregulatory population

Lymph node cells from TNCB-immune BALB/c mice fail to produce IFN-gamma when exposed to antigen in vitro. Conversely, lymph node cells of irradiated (550 rads) BALB/c mice produce IFN-gamma. Transfer experiments show that normal BALB/c mice contain cells which suppress IFN-gamma production. These downregulatory cells are CD4(+)alpha beta(+)and rearrange the invariant V alpha 14-J alpha 281 T cell receptor alpha chain, thus belonging to the NK T cell subset. Downregulatory cells probably act by producing IL-4 as their effect is blocked by mAb to IL-4.     

Trypanosoma gambiense: Enhancement of agglutinin and protection in subpopulations by immune spleen cells

On Day 5 after immunization with Trypanosoma gambiense, spleens were removed from immune mice. Spleen cell suspensions were passed through a glass bead column and separated into filtrate and adherent cell subpopulations. Each subpopulation was transferred into normal mice intraperitoneally, and the production of agglutinins and the protection against experimental infection with T. gambiense were studied in vivo. The adherent subpopulation contained cells which were capable of producing and releasing the agglutinin into the serum of the recipient, but the filtrate did not contain such cells.The adherent fraction was found to be effective in the prevention of experimental infection, but the filtrate was only slightly effective. When both cell subpopulations were mixed together, immune responses were enhanced. With cortisone and anti-mouse thymic cell serum treatment before immunization with trypanosomal antigen, agglutinin production was greatly suppressed, and the mice were not protected against experimental infection. However, after treatment of immune spleen cells in vitro with anti-mouse thymic cell serum, recipients of viable cells showed agglutinin production and were found to withstand infection.     

BALB/c小鼠作为单纯疱疹病毒1型感染模型的免疫学分析

在单纯疱疹病毒1型(herpes simplex virus type 1,HSV-1)小鼠感染及其相关研究中,临床病理和免疫学指标对其分析具有重要技术意义。本研究观察了HSV-1在不同条件下感染BALB/c小鼠后的多个免疫学指标,包括外周血单核细胞(peripheral blood mononuclear cell,PBMC)群体中树突细胞比例及功能、血清中和抗体水平、PBMC中HSV-1抗原特异性T细胞水平,以及潜伏感染期小鼠神经组织中CD8^＋ T细胞浸润情况。结果显示,HSV-1毒株Mckrae、17＋以角膜及滴鼻途径感染3周龄及6周龄BALB/c小鼠后,小鼠PBMC中树突细胞数量增加,并显示出刺激病毒抗原特异性T细胞增殖的能力。病毒感染后35 d,小鼠PBMC中未检测到白细胞介素4(interleukin 4,IL-4)^＋抗原特异性T细胞,但能检测到低水平的γ干扰素(interferon γ,IFN-γ)^＋抗原特异性T细胞;小鼠血清中未检测到或仅能检测到低水平的中和抗体。HSV-1以皮下及足垫注射途径感染BALB/c小鼠90 d后,足垫感染途径较皮下感染诱导出更高水平的血清中和抗体,PBMC中可检测到IL-4^＋及IFN-γ^＋抗原特异性T细胞,但不同毒株及小鼠周龄之间出现T细胞反应程度差异。组织病理学结果表明,各组小鼠三叉神经组织中均有CD8^＋ T细胞浸润。这些结果提示,不同HSV-1毒株以不同途径感染不同周龄BALB/c小鼠后,均可刺激树突细胞成熟及呈递病毒抗原,但血清中和抗体及PBMC中病毒抗原特异性T细胞水平在不同毒株、感染途径及小鼠周龄之间有差异。