Selective up-regulation of macrophage function in granulocyte-macrophage colony-stimulating factor transgenic mice.

Peritoneal and pleural cells from mice transgenic for GM-CSF were studied with regard to their phenotype and functional capacity, and compared with cells from normal littermates. Transgenic mice showed markedly elevated peritoneal and pleural cell counts compared with littermates, and a significantly higher proportion of cells in the transgenic populations were macrophage in phenotype. Transgenic macrophages were larger than the littermate cells, showing abundant foamy cytoplasm and enhanced spreading on plastic. Analysis by flow cytometry showed a more than sixfold increased expression of the macrophage activation markers MAC-2 and MAC-3, but not other markers, on transgenic macrophages. Superoxide production was measured in whole cell populations, both in their basal state and in response to particulate (zymosan) and soluble (PMA) stimuli. Both basal and stimulated superoxide production were markedly elevated in transgenic mice of 12 wk of age, with the largest differences seen in response to PMA. In younger mice, however, only PMA-stimulated superoxide production was significantly greater in transgenic macrophages than in littermate cells and levels of superoxide were generally lower than those seen in 12-wk-old mice. These findings suggest that the enhanced functional capacity of transgenic cells is a maturation-dependent event. In contrast to these findings, drug-dependent cytotoxicity assays performed on cells from 12-wk-old mice revealed no significant differences in killing capacity between the two mouse strains. Taken together these data indicate a selective rather than uniform functional up-regulation in transgenic macrophages compared with their littermates, with a time scale suggestive of a maturational rather than activation process. These findings may provide an indication of the functional macrophage phenotype resulting from long term exposure to GM-CSF in vivo, and help to explain the macrophage-associated pathology seen in GM-CSF-transgenic mice.     

Assessment of cell-mediated hypersensitivity against coxsackievirus B3 viral-induced myocarditis utilizing hypertonic salt extracts of cardiac tissue.

Hypertonic KCl extracts prepared from heart tissues of adolescent CD-1 mice inoculated with coxsackievirus B3 (CVB3) were tested for antigenicity in evaluating cell-mediated sensitivity to CVB3 virus utilizing the agarose droplet cell-migration-inhibition assay. Immune mouse peritoneal exudate cells (IMPEC) from mice immunized against CVB3 virus and Freund's complete adjuvant were specifically inhibited in the cell-migration-inhibition assay with graded doses of KCl-extracted antigen and purified protein derivative (PPD). Unimmunized for "normal" mouse peritoneal exudate cells (NMPEC) were not inhibited in the presence of the CVB3 KCl extracts. KCl heart extracts from mice inoculated with a cardiotropic strain of antigenically distinct mengovirus failed to inhibit CVB3 IMPEC, and noncardiac KCl extracts of liver and spleen from CVB3-inoculated mice also failed to inhibit cellular migration of CVB3 IMPEC. Reciprocal specificity experiments utilizing KCl-extracted antigens from mice infected with antigenically distinct cardiotropic mengovirus failed to inhibit cellular migration of IMPEC from mice immunized against the mengovirus. Serum-blocking power experiments indicate the antigenic KCl extracts failed to bind virus-neutralizing antibodies, indicating absence of detectable quantities of virion antigens. The results indicate that inoculation of mice with CVB3 virus results in the appearance of a new antigen(s) in cardiac tissue reacting with CVB3-IMPEC, but not with mengovirus IMPEC.     

Mechanisms of protective immunity against Schistosoma mansoni infection in mice vaccinated with irradiated cercariae. IV. Analysis of the role of IgE antibodies and mast cells

Mice resistant to challenge infection with Schistosoma mansoni by vaccination with highly irradiated cercariae were examined for the presence of circulating IgE antibodies and peritoneal mast cells sensitized against schistosome antigens. Significant levels of SWAP- or CAP-specific IgE antibodies could not be detected by solid phase radioimmunoassay in the sera of C57BL/6 mice during the first 6 wk after vaccination. Similarly, heatlabile antibodies capable of passively sensitizing normal mast cells for degranulation in response to SWAP could not be identified in the same sera. In contrast, peritoneal mast cells harvested from C57BL/6 mice 2 wk or later after vaccination gave strong degranulation responses when challenged with SWAP or CAP. Thus, vaccination with irradiated cercariae induces an unusual form of immediate-type hypersensitivity in which mast cells become sensitized in the absence of detectable circulating IgE antibodies. Mice deficient in mast cells (W/Wv mutant strain) were observed to develop the same resistance to challenge infection after vaccination with irradiated cercariae as nondeficient littermates. Similarly, vaccinated SJL/J mice were found to mount an extremely weak IgE response as measured by mast cell degranulation yet displayed the same level of resistance to challenge infection as other inbred mice developing potent mast cell responses. These findings argue that IgE antibodies and mast cells are not essential components in the effector mechanism of irradiated vaccine-induced immunity against schistosome infection.     

Eosinophils in the cerebrospinal fluid of mice infected with Angiostrongylus cantonensis are resistant to apoptosis

Interleukin-5 (IL-5) transgenic mice were used to assess the immunological features of CSF eosinophils from mice infected with Angiostrongylus cantonensis. CSF eosinophils were hypodense by day 14 post infection (p.i.). CSF eosinophils survived longer in vitro than peritoneal eosinophils collected from cadmium sulphate (CdSO₄) -treated normal IL-5 transgenic mice. Apoptosis was measured by Annexin V binding and the presence of a distinct laddering pattern of DNA fragmentation on agarose electrophoresis. Regardless of the presence or absence of Actinomycin D, CSF eosinophils collected from IL-5 transgenic mice from days 15–36 p.i. exhibited less apoptosis than peritoneal eosinophils collected from uninfected IL-5 transgenic mice. CSF eosinophils collected from A. cantonensis infected C57BL/6 mice at days 15–34 p.i. showed elongation of survival time and less apoptosis during in vitro cultivation. Reduced apoptosis was noted only in CSF eosinophils, but not in peritoneal eosinophils recovered from the same infected IL-5 transgenic mice. CPP32/Caspase 3 activity of cultured peritoneal eosinophils from both infected and uninfected IL-5 transgenic mice was higher than that of cultured CSF eosinophils. Stimulation with A23187 readily induced apoptosis of peritoneal eosinophils, but not CSF eosinophils or peritoneal eosinophils cultured with mouse recombinant IL-5. The latter cells were morphologically identical to hypodense eosinophils. RT-PCR analysis indicated that bcl-2 and bcl-x_L mRNA expression was higher in CSF eosinophils compared with peritoneal eosinophils and this expression in the latter cells was upregulated after culture with mouse recombinant IL-5. These results suggest that CSF eosinophils, shifting to hypodense status through an accumulation from peripheral blood, are resistant to apoptosis. These changes may explain the long-lasting, helminthotoxic and neurotoxic actions of CSF eosinophils in A. cantonensis infection.     

Eosinophils in the cerebrospinal fluid of mice infected with Angiostrongylus cantonensis are resistant to apoptosis.

Interleukin-5 (IL-5) transgenic mice were used to assess the immunological features of CSF eosinophils from mice infected with Angiostrongylus cantonensis. CSF eosinophils were hypodense by day 14 post infection (p.i.). CSF eosinophils survived longer in vitro than peritoneal eosinophils collected from cadmium sulphate (CdSO₄) -treated normal IL-5 transgenic mice. Apoptosis was measured by Annexin V binding and the presence of a distinct laddering pattern of DNA fragmentation on agarose electrophoresis. Regardless of the presence or absence of Actinomycin D, CSF eosinophils collected from IL-5 transgenic mice from days 15–36 p.i. exhibited less apoptosis than peritoneal eosinophils collected from uninfected IL-5 transgenic mice. CSF eosinophils collected from A. cantonensis infected C57BL/6 mice at days 15–34 p.i. showed elongation of survival time and less apoptosis during in vitro cultivation. Reduced apoptosis was noted only in CSF eosinophils, but not in peritoneal eosinophils recovered from the same infected IL-5 transgenic mice. CPP32/Caspase 3 activity of cultured peritoneal eosinophils from both infected and uninfected IL-5 transgenic mice was higher than that of cultured CSF eosinophils. Stimulation with A23187 readily induced apoptosis of peritoneal eosinophils, but not CSF eosinophils or peritoneal eosinophils cultured with mouse recombinant IL-5. The latter cells were morphologically identical to hypodense eosinophils. RT-PCR analysis indicated that bcl-2 and bcl-x_L mRNA expression was higher in CSF eosinophils compared with peritoneal eosinophils and this expression in the latter cells was upregulated after culture with mouse recombinant IL-5. These results suggest that CSF eosinophils, shifting to hypodense status through an accumulation from peripheral blood, are resistant to apoptosis. These changes may explain the long-lasting, helminthotoxic and neurotoxic actions of CSF eosinophils in A. cantonensis infection.     

转基因和基因敲除内脂素对小鼠脂肪积累的对比研究

目的内脂素（visfatin）也被叫做尼克酰胺磷酸核糖基转移酶,是一种脂肪因子,研究表明其与肥胖有关,但是与脂肪积累的关系仍然不明确,本研究是以内脂素转基因和内脂素基因敲除杂合子小鼠为对象,研究内脂素与脂肪积累的关系。方法 Western blot法对比分析转基因、基因敲除杂合子和野生型小鼠脂肪组织中内脂素表达水平。从2月龄开始对3种雌性小鼠饲喂高脂饲料,分别在2、4、6、8、9月龄测定其体重变化,并在9月龄时利用磁共振成像定性观测小鼠脂肪积累及分布,称量皮下和腹腔脂肪总重量并对腹腔脂肪组织进行组织学观察。结果内脂素转基因小鼠脂肪组织中内脂素的表达量比野生小鼠增加37%,基因敲除杂合子小鼠比野生小鼠降低了55%。饲喂7个月高脂饲料后,转基因小鼠体重平均27.8±0.8 g,野生小鼠体重平均33.6±1.1 g,基因敲除杂合子小鼠体重平均37.6±1.9 g。皮下和腹腔脂肪总重量测定结果显示转基因小鼠的脂肪总重量比野生小鼠降低了40%,基因敲除杂合子小鼠的脂肪总重量比野生小鼠增加了37%,组织学染色显示,内脂素转基因小鼠的平均单个脂肪细胞面积最小,而基因敲除杂合子小鼠面积最大。结果证实,内脂素表达量与体重、皮下和内脏脂肪总重量及脂肪细胞大小呈负相关。结论在饲喂高脂饲料的情况下,内脂素可以抑制脂肪的积累。     

Expression of a Truncated, Kinase-Defective TGF-β Type II Receptor in Mouse Skeletal Tissue Promotes Terminal Chondrocyte Differentiation and Osteoarthritis

Members of the TGF-β superfamily are important regulators of skeletal development. TGF-βs signal through heteromeric type I and type II receptor serine/threonine kinases. When over-expressed, a cytoplasmically truncated type II receptor can compete with the endogenous receptors for complex formation, thereby acting as a dominant-negative mutant (DNIIR). To determine the role of TGF-βs in the development and maintenance of the skeleton, we have generated transgenic mice (MT-DNIIR-4 and -27) that express the DNIIR in skeletal tissue. DNIIR mRNA expression was localized to the periosteum/perichondrium, syno-vium, and articular cartilage. Lower levels of DNIIR mRNA were detected in growth plate cartilage. Transgenic mice frequently showed bifurcation of the xiphoid process and sternum. They also developed progressive skeletal degeneration, resulting by 4 to 8 mo of age in kyphoscoliosis and stiff and torqued joints. The histology of affected joints strongly resembled human osteo-arthritis. The articular surface was replaced by bone or hypertrophic cartilage as judged by the expression of type X collagen, a marker of hypertrophic cartilage normally absent from articular cartilage. The synovium was hyperplastic, and cartilaginous metaplasia was observed in the joint space.

We then tested the hypothesis that TGF-β is required for normal differentiation of cartilage in vivo. By 4 and 8 wk of age, the level of type X collagen was increased in growth plate cartilage of transgenic mice relative to wild-type controls. Less proteoglycan staining was detected in the growth plate and articular cartilage matrix of transgenic mice. Mice that express DNIIR in skeletal tissue also demonstrated increased Indian hedgehog (IHH) expression. IHH is a secreted protein that is expressed in chondrocytes that are committed to becoming hypertrophic. It is thought to be involved in a feedback loop that signals through the periosteum/ perichondrium to inhibit cartilage differentiation. The data suggest that TGF-β may be critical for multifaceted maintenance of synovial joints. Loss of responsiveness to TGF-β promotes chondrocyte terminal differentiation and results in development of degenerative joint disease resembling osteoarthritis in humans.

     

Transgenic expression of the muscle-specific intermediate filament protein desmin in nonmuscle cells

The coding region of the hamster desmin gene was fused to the 5' flanking sequences of the hamster vimentin gene and introduced into the germ line of mice. The expression of this intermediate filament gene construct (pVDes) was analyzed at the RNA and protein level in transgenic mice as well as in fibroblast cell lines and primary hepatocyte cultures derived from these mice. In all transgenic mice, the pVDes-encoded protein was coexpressed with mouse vimentin in a tissue-specific fashion and was indistinguishable from normal hamster desmin. Culturing of transgenic hepatocytes induced desmin expression indicating that 3.2 kbp of the vimentin gene 5' region regulates both tissue-specific and tissue culture-induced intermediate filament protein expression. Immunohistochemical staining and double-label immunoelectron microscopy of cultured transgenic fibroblasts showed that the pVDes protein assembled into intermediate filaments which colocalized with the mouse vimentin filaments. Endogenous vimentin RNA levels were not influenced by high-level pVDes expression. The coexpression of desmin and vimentin in nonmuscle cells did not result in detectable developmental, morphological, or physiological abnormalities.     

Both normal and tumor cells produce basic fibroblast growth factor

We have previously purified from human placenta a basic fibroblast growth factor (FGF)-like molecule which stimulates the production of plasminogen activator (PA) and collagenase, induces DNA synthesis, produces an increase in motility in cultured bovine capillary endothelial (BCE) cells, and induces angiogenesis in vivo. The ability of basic FGF to stimulate PA production in BCE cells was used as an assay for the presence of basic FGF-like molecules in extracts of both normal and tumor-derived cultured cells. The identity of the PA-stimulatory activity with basic FGF was confirmed by its high affinity for heparin and by its cross-reactivity with antibodies to human placental basic FGF. Basic FGF-like molecules were identified in eight of ten cell lines tested, and the amount of FGF-like activity present in these cells bore no relation to their origin from normal or tumor tissue. The test cells, BCE cells, had one of the highest levels of FGF-like activity, suggesting that it may have an autocrine role in these cells.     

VEGF causes pulmonary hemorrhage, hemosiderosis, and air space enlargement in neonatal mice

To determine whether increased levels of VEGF disrupt postnatal lung formation or function, conditional transgenic mice in which VEGF 164 expression was enhanced in respiratory epithelial cells were produced. VEGF expression was induced in the lungs of VEGF transgenic pups with doxycycline from postnatal day 1 through 2 and 6 wk of age. VEGF levels were higher in bronchoalveolar lavage fluid (BALF) and lung homogenates of VEGF transgenic mice compared with endogenous VEGF levels in controls. Neonatal mortality was increased by 50% in VEGF transgenic mice. Total protein content in BALF was elevated in VEGF transgenic mice. Surfactant protein B protein expression was unaltered in VEGF transgenic mice. Although postnatal alveolar and vascular development were not disrupted by VEGF expression, VEGF transgenic mice developed pulmonary hemorrhage, alveolar remodeling, and macrophage accumulation as early as 2 wk of age. Electron microscopy demonstrated abnormal alveolar capillary endothelium in the VEGF transgenic mice. In many locations, the endothelium was discontinuous with segments of attenuated endothelial cells. Large numbers of hemosiderin-laden macrophages and varying degrees of emphysema were observed in adult VEGF transgenic mice. Overexpression of VEGF in the neonatal lung increased infant mortality and caused pulmonary hemorrhage, hemosiderosis, alveolar remodeling, and inflammation.     

Immunoregulation in disseminated murine histoplasmosis: disturbances in the production of interleukins 1 and 2

Production of IL 1 and IL 2 by splenocytes from C57BL/6 mice was measured at wk 1, 3, 8, and 14 after i.v. inoculation with 6 X 10(5) Histoplasma capsulatum (Hc) yeasts. As compared with age-matched controls, IL 1 production by splenocytes from Hc-infected mice was reduced severely at wk 1 and 3 of infection, greater than normal at wk 8, and within normal range at wk 14. IL 2 production was also reduced at wk 1 and 3 of infection; it was normal at wk 8 and was elevated at wk 14. Indomethacin and catalase failed to restore IL 1 production by splenocytes from infected mice, and exogenous IL 1 did not augment IL 2 production by these cells. A factor capable of suppressing the activity of IL 2 was detected in supernatants of concanavalin A-stimulated splenocytes from infected animals at wk 1 and 3 of infection, respectively. No factor capable of suppressing IL 1 activity was detected. Thus, the deficits of cell-mediated immunity in mice with systemic Hc infection may derive, in part, from impaired amplification of the immune response consequent to abnormal generation of IL 1 and IL 2.     

In vivo administration of recombinant granulocyte-macrophage colony-stimulating factor results in a reversible inhibition of primary B lymphopoiesis

To determine if in vivo administration of granulocyte-macrophage CSF (GM-CSF) affects production of B lymphocytes in the bone marrow, mice were treated with the cytokine and the kinetics of B cell production was analyzed. After 1 wk of GM-CSF treatment, the number of B cell progenitors that express the B220 Ag had fallen fivefold and surface IgM expressing B cells were barely detectable. Although cellularity in the spleen had increased two-fold, due in part to an increase in the number of granulocyte-macrophage progenitor cells, splenic B cell levels were not affected by the GM-CSF treatment. Although numbers of marrow B cells and their immediate progenitors declined due to cytokine treatment, cells capable of rapidly restoring B lymphopoiesis were present in that tissue. After cessation of GM-CSF treatment, B lymphopoiesis resumed in the marrow of the mice and rebounded to supernormal levels at 1 wk after the last GM-CSF injection. This effect may be due to actions of GM-CSF on the B lymphopoietic support capability of the marrow environment, because the overproduction of B cells was not observed when marrow from the GM-CSF donors was used to reconstitute sublethally irradiated severe combined immunodeficient mice.     

Establishment of spermatogenesis in neonatal bovine testicular tissue following ectopic xenografting varies with donor age

Ectopic testicular xenografting can be used to investigate spermatogenesis and as an alternative means for generating transgenic spermatozoa in many species. Improving the efficiency of spermatogenesis in xenografted testicular tissue will aid in the application of using this approach. The present study was conducted to evaluate age-related differences in the establishment of spermatogenesis in grafted testicular tissue from bulls between 2 and 16 wk of life. Testicular tissue was ectopically xenografted under the skin on the backs of castrated nude mice and subsequently evaluated for growth, testosterone production, and establishment of spermatogenesis 24 wk after grafting. The greatest weight increases occurred in donor tissue from calves of the ages 2, 4, and 8 wk compared with the ages of 12 and 16 wk. Recipient mouse serum testosterone concentration was at normal physiological levels 24 wk after grafting and no significant differences were detected between recipients grafted with testicular tissue from bull calves of different ages. The development of germ cells to elongated spermatids were observed in seminiferous tubules of grafts from donor calves of the ages 4, 8, 12, and 16 wk but not observed in grafts from 2-wk donors, which contained round spermatids as the most advanced germ cell stage. Grafts from 8-wk donors contained a significantly higher (10-fold) average percentage of seminiferous tubules with elongated spermatids than all other donor ages. These data demonstrate differences in the ability of testicular tissue from donor animals of different ages to establish spermatogenesis following ectopic testicular xenografting.     

Nonmyeloablative bone marrow transplantation of BXSB lupus mice using fully matched allogeneic donor cells from green fluorescent protein transgenic mice

Male BXSB mice, a mouse model of systemic lupus erythematosus, were given bone marrow transplants (BMT) at 20 wk of age using MHC-matched donor cells and nonmyeloablative conditioning (550 cGy irradiation). Transplanted mice and irradiation controls were followed for a period of 20 wk. Mice transgenic for green fluorescent protein were used as donors to allow tracking of donor cells and a determination of chimerism. Radiation controls had reduced renal pathology at 10 wk posttransplant, but not at 20 wk compared with untreated mice, while nonmyeloablative BMT mice had significantly reduced pathology at both time intervals. The monocytosis characteristic of older BXSB mice was also reduced by BMT, but the treatment did not prevent production of Ab to dsDNA. A stable chimerism of 24-40% donor CD45-positive cells was achieved in spleen and bone marrow, and there was no evidence of clinical graft vs host disease. Donor cells were detected in most recipient organs, notably the thymus and renal glomeruli. The results suggest that complete depletion of mature lymphocytes or of progenitor stem cells is not required to control lupus nephritis in BXSB mice.     

IgE generation and mast cell effector function in mice deficient in IL-4 and IL-13

IL-4 and IL-13 are potent cytokines that drive production of IgE, which is critical to the development of atopic disease. In this study, we directly compared IgE generation and IgE-dependent mast cell effector function in mouse strains lacking IL-4, IL-13, IL-4 + IL-13, or their common receptor component, IL-4Ralpha. Although serum IgE was undetectable under resting conditions in most animals deficient in one or both cytokines, peritoneal mast cells from mice lacking IL-4 or IL-13 had only partial reductions in surface IgE level. In contrast, peritoneal mast cells from IL-4/13(-/-) and IL-4Ralpha(-/-) animals were severely deficient in surface IgE, and showed no detectable degranulation following treatment with anti-IgE in vitro. Surprisingly, however, intradermal challenge with high concentrations of anti-IgE Ab induced an ear-swelling response in these strains, implying some capacity for IgE-mediated effector function in tissue mast cells. Furthermore, upon specific immunization with OVA, both IL-4/IL-13(-/-) and IL-4Ralpha(-/-) mice produced detectable levels of serum IgE and Ag-specific IgG1, and generated strong ear-swelling responses to intradermal administration of anti-IgE. These findings suggest that a mechanism for IgE production exists in vivo that is independent of IL-4 or IL-13.     

Increased frequency of surface IgA-positive plasma cells in the intestinal lamina propria and decreased IgA excretion in hyper IgA (HIGA) mice, a murine model of IgA nephropathy with hyperserum IgA

Because abnormalities of mucosal immunity have been suggested in human IgA nephropathy, we examined the involvement of mucosal immunity in IgA deposition to the kidney in hyper IgA (HIGA) mice, which was established as a mouse model for human IgA nephropathy with hyperserum IgA. The number of surface IgA+B220- lymphocytes in the intestinal lamina propria (LP) of HIGA mice increased 2.7-fold at 30 wk of age as compared with those at 10 wk of age, whereas normal mice did not show such increase. The surface IgA+B220- LP lymphocytes spontaneously secreted IgA in culture. Morphological studies showed that the surface IgA+B220- lymphocytes of murine intestinal LP are identical with plasma cells (PCs). About 20% of IgA+B220- PC in LP expressed both Mac-1 and CD19, suggesting that they may derive from peritoneal B-1 cells. Cell cycle study on intestinal IgA-PCs using bromodeoxyuridine revealed no difference between HIGA mice and normal mice, suggesting that the high frequency of IgA-producing PCs in HIGA mice is not due to enhanced proliferation or prolonged survival of IgA-producing PCs in LP. In addition, IgA secretion into the gut lumen of HIGA mice decreased drastically (to one forth) with aging. These data suggest that the increased number of intestinal IgA-producing PCs and the down-regulation of IgA excretion into the intestinal lumen might synergistically contribute to the hyperserum IgA in HIGA mice and resultant IgA deposition to the kidney.     

Early role of CD4+ Th1 cells and antibodies in HER-2 adenovirus vaccine protection against autochthonous mammary carcinomas

HER-2 is an oncogenic tumor-associated Ag that is overexpressed in several human tumors including breast and ovarian cancer. The efficacy and mechanism of a HER-2-expressing recombinant adenoviral vaccine to protect against tumorigenesis was examined using HER-2 transgenic (BALB-neuT) mice, which develop spontaneous breast tumors in all 10 mammary glands, and also using a transplantable mouse tumor model. Vaccination beginning at 6-8 wk of age (through 19 wk of age) prevented development of spontaneous mammary tumors even after 50 wk, whereas the animals in the control groups had tumors in all mammary glands by 25 wk. Such long-term protection after the last boost has not been achieved previously in this transgenic mouse in which the oncogene is continuously spawning tumorigenesis. Using beta(2)-microglobulin-knockout, IFN-gamma-knockout, and B cell-deficient mice, CD4(+) and CD8(+) cell depletion, and Ab transfer studies, we show that induction of anti-HER-2/neu Abs are both necessary and sufficient for protection, and the IgG2a isotype is most effective. In contrast, CD8(+) T cells are not necessary at all, and CD4(+) T cells are necessary for only 36-48 h after immunization to provide help for B cells but not as effector cells. Equal protection in immunized mice deficient in FcgammaRI/III excluded an FcR-mediated mechanism. Anti-HER-2 serum not only inhibited growth of mammary tumor cell lines expressing HER-2 in vitro but also protected mice from tumors in vivo, suggesting a direct action of Ab on the tumor cells. Such a vaccine may provide Ab-mediated protection against HER-2-expressing breast cancers in humans.     

Immune Response against Hamster Erythrocytes in the Low-Responder Mouse Strains

C57BL/6 and AKR mice were treated with hamster erythrocytes (HRBC) in complete Freund's adjuvant (CFA) or incomplete Freund's adjuvant (IFA) and the development of delayed hypersensitivity and antibody production were examined. 1) Delayed hypersensitivity against HRBC antigen, as determined by the peritoneal macrophage disappearance test, was detected in mice sensitized with HRBC in CFA but not in those sensitized with HRBC in IFA. 2) Antibody production against HRBC or hapten TNP after a booster injection of HRBC or trinitrophenylated HRBC (TNP-HRBC) in saline was enhanced by pretreatment with HRBC in CFA or IFA. 3) Delayed hypersensitivity was not detectable after a booster sensitization with HRBC in CFA in mice which had been pretreated with HRBC in IFA 2 weeks earlier. In the mice treated with both HRBC in IFA (day ?21) and in CFA (day ?7), however, an enhanced antibody production against HRBC or TNP was detected after an intravenous injection with HRBC or TNP-HRBC in saline (day 0). These results suggest that sensitized effector lymphocytes in delayed hypersensitivity and helper cells in antibody production may be derived from the same pool of unprimed T cells. The pool of unprimed T cells with a capacity to differentiate into either type of primed T cells may be exhausted after pretreatment with the antigen in IFA, and the primed helper T cells may not be able to differentiate into sensitized lymphocytes even after sensitization with the antigen in CFA, which favors development of delayed hypersensitivity in normal controls.