Thrombopoietin-induced CXC chemokines,NAP-2 and PF4, suppress polyploidization and proplatelet formation during megakaryocyte maturation

BACKGROUND: We previously reported that the expressions of two CXC chemokines, neutrophil activating peptide-2 (NAP-2) and platelet factor-4 (PF-4), were induced by megakaryocyte-specific cytokine thrombopoietin (TPO) in mouse bone marrow megakaryocytes. The roles of these chemokines on megakaryocyte maturation/differentiation processes, including polyploidization and proplatelet formation (PPF) remain unresolved. RESULTS: NAP-2 and PF-4 suppressed the PPF of mature megakaryocytes freshly prepared from mouse bone marrow as well as that of the megakaryocyte progenitors, c-Kit+CD41+ cells, isolated from mouse bone marrow and cultured with TPO. NAP-2 and PF-4 inhibited polyploidization of c-Kit+CD41+ cells in the presence of TPO, and also inhibited the proliferation of c-Kit+CD41+ cells. CONCLUSIONS: NAP-2 and PF-4 produced by TPO stimulation in megakaryocytes suppress megakaryocyte maturation and proliferation as a feedback control.     

IL-6和IL-11对脐血CD34+细胞诱导分化为巨核细胞的影响

目的： 探讨白细胞介素－6(IL-6)和白细胞介素－11(IL-11)对脐血CD34+细胞诱导分化为巨核细胞及其产生血小板的影响。方法: 采用免疫磁珠法(MACS)分选8例健康产妇足月顺产的胎儿脐血中CD34+细胞，以含血小板生成素（TPO 50 μg/L）、白细胞介素-3（IL-3 10 μg/L）、干细胞因子（SCF 50 μg/L）的无血清培养基作为对照组，分别添加10 μg/L IL-6、IL-11、IL-6+IL-11作为实验组，培养14 d后观察结果。利用细胞计数仪检测单个核细胞数；流式细胞仪计数培养体系中的CD41+细胞和血小板；用倒置显微镜观察培养体系中的细胞生长情况；用显微镜和流式细胞仪观察凝血酶诱导后的血小板凝集情况。结果: 各实验组单个核细胞数与对照组无明显区别（P>0.05），而CD41+细胞和血小板数量明显多于对照组(P<0.05)。培养第14 d后倒置显微镜下可见实验组中血小板样颗粒物明显多于对照组，而且经凝血酶诱导后有明显血小板凝集。结论: IL-6和IL-11可诱导脐血中CD34+细胞分化为巨核细胞并产生功能性血小板。     

抑制性受体LAIR-1对巨核谱系分化的调节作用

 目的 研究抑制性受体LAIR-1在巨核谱系细胞的表达及其对巨核细胞分化的调节作用。方法 采用流式细胞术和激光共聚焦显微镜检测LAIR-1在巨核谱系细胞的表达；免疫磁珠法纯化脐血CD34+细胞，体外无血清培养系统诱导CD34+细胞向巨核细胞分化，观察LAIR-1被抗体或配体交联激活后对巨核细胞分化的影响。结果 LAIR-1表达于人骨髓CD34+CD41a+和CD41a+CD42b+细胞以及脐血CD34+CD41a-和CD34+CD41a+细胞；脐血CD34+细胞向巨核细胞分化过程中，LAIR-1表达在倍性为2N和4N的不成熟CD41a+细胞上；交联激活LAIR-1分子能够抑制脐血CD34+细胞向巨核细胞的分化。结论 LAIR-1可能是参与巨核细胞早期分化发育的一种新的负调控分子。     

A monoclonal antibody against rat platelets. I. Tissue distribution in vitro and in vivo.

In this study we describe a new monoclonal antibody (MoAb PL.1) against rat platelets. Immunohistology of various rat tissues showed staining of platelets, especially in the spleen, and staining of megakaryocytes in bone marrow and spleen red pulp. In the liver small platelet aggregates and endothelial cells were stained. After in-vivo administration of MoAb PL.1 an acute severe thrombocytopenia was observed. In general the distribution of the antibody and/or antibody-coated platelet aggregates showed the same pattern as after in-vitro incubation, i.e. staining of rat platelets and platelet aggregates in spleen red pulp, and staining of megakaryocytes in spleen and bone marrow. Platelet aggregates were observed in the liver and electron microscopy indicated that they were associated with Kupffer cells. Furthermore, liver endothelial cells were positively stained. Comparison of the molecular weight of the antigens recognized by this MoAb and by human anti-platelet MoAbs, as well as comparison of staining patterns of megakaryocytes indicated that MoAb PL.1 is probably directed to a GPIIb/IIIa complex analogue. Since MoAb PL.1 is of the non-complement-binding mouse IgG1 isotype, it can be used for studying clearance of platelet aggregates by Fc-receptors of the MPS. It also promises to be a useful tool in the study of platelet involvement in rats with experimental nephritis.     

Human/BALB radiation chimera engrafted with splenocytes from patients with idiopathic thrombocytopenic purpura produce human platelet antibodies.

We have previously shown that lethally irradiated normal strains of mice, radioprotected with severe combined immunodeficient (SCID) bone marrow, can be engrafted with human peripheral blood mononuclear cells (PBMC). The human/mouse radiation chimera can mount marked humoral and cellular responses to recall antigens, as well as primary responses. In the present study, we adoptively transferred splenocytes from patients with chronic immune thrombocytopenic purpura (ITP) into lethally irradiated BALB/c mice, radioprotected with SCID bone marrow. High titres of total human immunoglobulin appeared as early as 2 weeks post-transplant and declined after 6 weeks, while human anti-human platelet antibodies were detected 2-8 weeks after the transfer of splenocytes. The immunoglobulin G (IgG) fraction contained antibodies against glycoprotein (GP) IIb/IIIa (CD41) or GPIb/IX (CD42). The human platelet antibodies showed a low level of cross-reactivity with mouse platelets, and thrombocytopenia in the animals was not observed. Splenocytes from individual ITP patients differed in their capacity to produce either human platelet antibodies or total human immunoglobulin. Furthermore, antibodies produced in the murine system were not always identical to the original antibodies present in the serum of the patients. The study of the serological aspects of autoantibodies against human platelets in an animal model might be useful for the investigation of potential therapeutics in ITP.     

Characterisation of the epitope for a herpes simplex virus glycoprotein B-specific monoclonal antibody with high protective capacity

Monoclonal antibody (MAb) 2c, specific for glycoprotein B of herpes simplex virus (HSV), had been shown to mediate clearance of infection from the mucous membranes of mice, thereby completely inhibiting mucocutaneous inflammation and lethality, even in mice depleted of both CD4(+) and CD8(+) cells. Additionally, ganglionic infection was highly restricted. In vitro, MAb 2c exhibits a potent complement-independent neutralising activity against HSV type 1 and 2, completely inhibits the viral cell-to-cell spread as well as the syncytium formation induced by syncytial HSV strains (Eis-Hübinger et al. in Intervirology 32:351-360, 1991; Eis-Hübinger et al. in J Gen Virol 74:379-385, 1993). Here, we describe the mapping of the epitope for MAb 2c. The antibody was found to recognise a discontinuous epitope comprised of the HSV type 1 glycoprotein B residues 299 to 305 and one or more additional discontinuous regions that can be mimicked by the sequence FEDF. Identification of the epitope was confirmed by loss of antibody binding to mutated glycoprotein B with replacement of the epitopic key residues, expressed in COS-1 cells. Similarly, MAb 2c was not able to neutralise HSV mutants with altered key residues, and MAb 2c was ineffective in mice inoculated with such mutants. Interestingly, identification and fine-mapping of the discontinuous epitope was not achieved by binding studies with truncated glycoprotein B variants expressed in COS cells but by peptide scanning with synthetic overlapping peptides and peptide key motif analysis. Reactivity of MAb 2c was immensely increased towards a peptide composed of the glycoprotein B residues 299 to 305, a glycine linker, and a C-terminal FEDF motif. If it could be demonstrated that antibodies of the specificity and bioactivity of MAb 2c can be induced by the epitope or a peptide mimicking the epitope, strategies for active immunisation might be conceivable.     

Anti-CD31 delays platelet adhesion/aggregation at sites of endothelial injury in mouse cerebral arterioles.

The arterioles on the surface of the mouse brain (pial arterioles) were observed by in vivo microscopy. A focus of minor endothelial damage was produced in a single pial arteriole in each mouse by briefly exposing the site to a helium neon laser after an intravenous injection of Evans blue. Mice were injected 10 minutes before injury with a monoclonal antibody (MAb) to mouse CD31, also known as platelet endothelial cell adhesion molecule. This treatment doubled (P < .01) the time required for the laser to produce a recognizable platelet aggregate. In additional experiments, an MAb to mouse CD61 and an MAb to mouse intercellular adhesion molecule 1 had no effect. The data support previous observations indicating that platelet adhesion/aggregation in this model is induced by endothelial injury without exposure of basal lamina. The data are consistent with the hypothesis that the endothelial injury exposes or activates a platelet endothelial cell adhesion molecule on the endothelium which is blocked by the MAb directed against CD31. This may be the first demonstration of an effect of an anti-platelet endothelial cell adhesion molecule on platelet endothelial cell adhesion molecule on platelet adhesion/aggregation in vivo.     

Effect of human blood mononuclear cell populations in antibody dependent cellular cytotoxicity (ADCC) using two murine (CO17-1A and Br55-2) and one chimeric (17-1A) monoclonal antibodies against a human colorectal carcinoma cell line (SW948)

Peripheral blood mononuclear cells (PBMC) from healthy individuals were studied for their lytic capability in ADCC using SW948 (a human colorectal carcinoma cell line) as target cells. Three monoclonal antibodies (MAbs) were used: two mouse MAbs (IgG2A) against the antigenic structures CO17-1A and BR55-2 respectively and one chimeric MAb 17-1A (IgG1) (mouse-human). Three kinds of effector cells were prepared. PBMC were purified on a Ficoll-Isopaque gradient (FIP cells) (a mixture of lymphocytes and monocytes). To obtain pure monocytes (greater than 90%), PBMC were centrifuged on a Nycodenz gradient (Nycodenz cells). Highly purified lymphocytes (greater than 98%) were obtained by treatment of FIP cells with iron powder and removal of phagocytic cells (PBL cells). Monocytes had the highest lytic capability. FIP cells were less effective than monocytes. PBL cells had the poorest killing activity. In reconstitution experiments addition of increasing amount of monocytes to PBL resulted in an augmented cytotoxicity. The numbers of Leu-M3+ cells, Leu-M5+ cells (monocytes) and CD16+ cells correlated positively to cytotoxicity. Higher concentration of MAb 17-1A was required to reach the same level of cytotoxicity using FIP cells as effector cells as compared to monocytes. MAb BR55-2 induced the same cytotoxic activity as MAb 17-1A. Combination of these two MAbs did not increase the lytic capability. Chimeric MAb 17-1A mediated ADCC in a dose-dependent fashion. The chimeric MAb was consistently more effective than the mouse MAb.     

Synthetic cytokines containing interleukin-3 exert potent megakaryopoietic activity

The shared properties of haematopoietic cytokines and their receptors have enabled the genetically engineered construction of several synthetic cytokines with increased haematopoietic activity and/or more desirable pharmacological characteristics. Thrombocytopenia remains a significant cause of morbidity in cancer patients undergoing allogeneic or autologous bone marrow/blood stem cell transplantation after myeloablative therapy including total body irradiation. Several in vitro, in vivo and preliminary clinical studies have demonstrated the efficacy of synthetic cytokines containing interleukin-3 in accelerating platelet recovery after radiotherapy-induced myelosuppression, enhancing G-CSF-mobilisation of CD34 positive cells for transplantation and increasing the ex-vivo expansion of myeloid and megakaryocytic progenitor cells. More randomised controlled clinical trials are needed to study the efficacy of the pre-transplant platelet mobilisation and the acceleration of the post-transplant platelet recovery. This also applies to cohort in vitro studies for expanding the production of CD41+ megakaryocytes from human bone marrow, mobilised peripheral blood and cord blood CD34 positive cells using myelopoietin as the only accepted synthetic cytokine containing interleukin-3.     

Anti-CD2 monoclonal antibodies prevent spontaneous and adoptive transfer of diabetes in the BB/Wor rat.

We studied the effects of anti-CD2 monoclonal antibodies (MAb) on spontaneous and induced autoimmune diabetes mellitus in diabetes-prone (DP) and diabetes-resistant (DR) BB/Wor rats. In DP rats, all anti-CD2 MAb prevented spontaneous diabetes and the adoptive transfer of diabetes with Con-A--stimulated acute diabetic spleen cells; OX34 prevented Poly I:C induced accelerated onset of diabetes and the adoptive transfer of diabetes with Con-A--stimulated RT6.1+ T cell depleted DR splenocytes. In DP rats, all anti-CD2 MAb except OX53 depleted CD4+ T cells, without depleting natural killer cells or CD8+ T cells. OX34 injected DR rats were profoundly depleted of CD4+ T cells without evidence of decreased CD8+ T cells, but were not protected against the induction of diabetes by RT6.1+ T-cell depletion and Poly I:C injections. We conclude that anti-CD2 MAbs protect against BB/Wor autoimmune diabetes by depleting CD4+ T cells, preventing the activation of effector cells, or by blocking CD2/ligand interaction between effector and target cells.     

Immunohistochemical, quantitative immunoelectron microscopic, and DNA cytofluorometric characterization of chemically induced rat malignant fibrous histiocytoma.

Malignant fibrous histiocytoma (MFH) was induced in rats by injection of 9,10-dimethyl-1,2-benzanthracene. Using cell suspensions prepared from the heterotransplanted nude mouse tumor as immunogen, a monoclonal antibody, (MAb), MEP-1, against fibroblastlike MFH tumor cells was generated. In the primary rat tumors and transplanted rat or nude mouse tumors, MEP-1 reacted specifically with the fibroblastlike cells but not with the histiocytelike cells or xanthoma cells. Anti-rat macrophage MAbs RM-1 and TRPM-3 did not stain the fibroblastlike cells, but both were reactive with the histiocytelike cells. Double stainings with both MEP-1 and RM-1 or TRPM-3 did not detect any double positive cells. Immunoelectron microscopy using these MAbs showed that the fibroblastlike cells were the major cell component of the primary and transplanted rat tumors and that their cell membrane was stained positively with MEP-1, but not for RM-1 or TRPM-3. By the double staining method using a MAb against prolyl 4-hydroxylase beta and MEP-1 or TRPM-3, this enzyme was demonstrated in MEP-1-positive cells but not in TRPM-3-positive cells. Results obtained by DNA cytofluorometry with 4,6-diamidino-2-phenylindole dihydrochloride staining or by the combined method of DNA cytofluorometry and indirect immunofluorescence, using MEP-1, RM-1, and TRPM-3, indicate that MEP-1-positive cells are neoplastic cells of rat MFH having proliferation activity. In the transplanted nude mouse tumors, no differentiation of MEP-1-positive rat tumor cells into histiocytelike cells was detected, and all histiocytelike cells were immunostained by F4/80 and most of them were positive for M5/114. These results suggest that fibroblastlike cells and intermediate cells are tumor cells of 9,10-dimethyl-1,2-benzanthracene-induced rat MFH showing differentiation toward fibroblasts and that histiocytelike cells are infiltrated macrophages.     

Rat brain xenografts reverse hypogonadism in mice immunosuppressed with anti-CD4 monoclonal antibody

Summary This study examines the effect of immunosuppression with monoclonal antibodies (MAb) against the murine CD4 (L3T4), a cell surface glycoprotein expressed primarily on helper T-lymphocytes, on the viability and function of rat neural xenografts placed in the third ventricle of hypogonadal (hpg) mice. The hpg mouse fails to synthesize hypothalamic gonadotrophin releasing hormone (GnRH) and consequently there is a drastic reduction in pituitary gonadotrophic hormone content and a failure of postnatal gonadal development (Cattanach et al. 1977). Three groups of male hpg mice received xenografts of day 1 post natal rat preoptic area (POA) tissue, a source of GnRH neurons, to their third ventricle. Those immunosuppressed with anti-CD4 MAb all showed surviving graft tissue thirty days post-transplant and half of this group had enlarged testes with all stages of spermatogenesis. In those hpg mice which were injected with saline alone, or with an anti-CD8 (Lyt-2) antibody there was no xenograft survival. These results suggest that the injection of monoclonal antibodies against the T-helper subset may provide an alternative means of immunosuppression aimed at the enhancement of survival of tissue grafts in the CNS.     

Isolation and characterization of autologous blood mononuclear cells used for auto-infusion together with monoclonal antibodies in tumor treatment

CO17-1A is a tumor associated antigen on colorectal carcinoma cells. A mouse monoclonal antibody of subclass IgG2A (MAb 17-1A) has been previously produced against the antigen for therapy. In a phase II study in patients with metastasizing colorectal carcinomas, leukapheresis was performed and isolated cells armed in vitro with MAb 17-1A. The mixture of MAb 17-1A and cells were infused into the patients. The aim of this procedure was to increase the number of cytotoxic cells in the tumor lesion. Two cell purification techniques (A and B) using an IBM 2991 Blood Cell Processor are described. Procedure B gave the highest yield of mononuclear cells (7.52 x 10(9) vs 5.17 x 10(9), p less than 0.01) as well as significantly higher total numbers of monocytes and NK cells. The relative ADCC activity of the two cell isolates were similar. A positive correlation between the frequency of Leu-M5+ cells (monocytes) and 51Cr release was observed. Increasing amounts of OKM1+ (CD11) cells suppressed ADCC. 35-40% of the cells bound MAb 17-1A after 1h incubation at room temperature. There was no substantial increase in cells binding MAb 17-1A upon further incubation. A strong positive correlation between the numbers of monocytes and cells binding MAb 17-1A was seen but also B lymphocytes, T lymphocytes and NK cells bound MAb 17-1A. More than 97% of the added MAb was unbound.     

An anti-CD3 monoclonal antibody protects mice against a lethal infection with Listeria monocytogenes through induction of endogenous cytokines.

Mice were protected against a lethal infection with Listeria monocytogenes when treated with low doses of an anti-CD3 monoclonal antibody (MAb). Injection of anti-CD3 MAb induced rapid production of endogenous tumor necrosis factor (TNF) in the spleens and endogenous gamma interferon (IFN-gamma) in the bloodstreams and spleens of mice. Administration of anti-Thy1.2 MAb or a combination of anti-CD4 MAb and anti-CD8 MAb resulted in suppression of anti-CD3 MAb-induced endogenous cytokine production and antilisterial resistance. Alternatively, in vivo depletion of anti-CD3 MAb-induced TNF and IFN-gamma by the simultaneous administration of antibodies against TNF and IFN-gamma suppressed anti-CD3 MAb-induced antilisterial resistance. Moreover, injection of anti-complement receptor type 3 (Mac-1, CD11b) resulted in inhibition of anti-CD3 MAb-induced antilisterial resistance. These results suggest that the preventive effect of anti-CD3 MAb might be due to activation of phagocytes by TNF and IFN-gamma induced by stimulating CD4+ T cells and CD8+ T cells with the MAb. Furthermore, treatment with anti-CD3 MAb did not inhibit establishment of acquired resistance against secondary infection with L. monocytogenes.     

非胰岛素依赖型糖尿病患者血小板活化与微血管病变关系初探

目的：探讨糖尿病患者血小板活化与微血管病变的关系。方法：采用流式细胞术测定77例非胰岛素依赖型糖尿病（NIDDM）患者（其中无微血管病变者41例,伴微血管病变者36例）及35例健康对照者的血小板颗粒膜糖蛋白（CD62p和CD63）、血小板膜表面糖蛋白（CD41、CD61和CD42b）及血小板凝血酶敏感蛋白（TSP）,同时用RIA检测血浆内皮素（ET）和空腹血浆胰岛素（FINS）。结果：NIDDM组血小板CD62p、CD63和TSP阳性的百分率（1.51±0.73%、4.93±1.06%、79.37±11.17%）和CD41、CD61的平均荧光道数值（MnX）（15.62±4.22、7.78±1.91）显著高于健康对照组（0.49±0.26%、2.22±0.61%、63.58±9.37%、9.86±1.05、3.03±0.43）（P〈0.05～0.01）,伴微血管病变组又明显高于无微血管病变组（P〈0.05～0.01）。NIDDM组血小板CD42b的阳性百分率显著低于健康对照组（P〈0.05）,但有无微血管病变组间的差异并不显著（P〉0.05）。糖尿病患者血小板CD62p、CD63、CD61和TSP与血浆ET呈显著正相关（r=0.57、0.52、0.37和0.33,P〈0.05～0.01）。结论：活化血小板测定对于糖尿病微血管病变的早期诊断具有重要的临床应用和研究价值。     

Cytokine-induced expansion of human CD34+ stem/progenitor and CD34+CD41+ early megakaryocytic marrow cells cultured on normal osteoblasts

Thrombocytopenia remains a significant cause of morbidity in cancer patients undergoing allogeneic bone marrow transplantation (BMT), which consumes millions each year for frequent platelet transfusions. Using a novel culture system containing appropriate cytokine(s) on a layer of normal human osteoblasts, we investigated the expansion of early megakaryocytic progenitor cells while maintaining the number of CD34+ stem/progenitor marrow cells in an attempt to provide an effective solution for the problem of post-transplant thrombocytopenia. After seven days of culture, normal human osteoblasts alone without cytokines significantly increased the number of CD34+ and CD34+CD41+ marrow cells. Among the various cytokine combinations tested, both stem cell factor (SCF), interleukin 3 (IL-3)+IL-11 and SCF+IL-3+IL-11+thrombopoietin (TPO) emerged as the most effective in expanding early CD34+CD41+ megakaryocytic cells. Early CD34+CD41+ megakaryocytic cells have increased by 3.1- and 4.7-fold compared with day 7 control cultures, and by 62- and 94-fold, respectively, compared with day 0 input, respectively. Also, late CD41+ megakaryocytic cells have increased by 15.4- and 27.5-fold compared with day 7 control cultures in the presence of the same two combinations. In addition, the same cytokine combinations achieved 17.6- and 13.3-fold increases in the number of CD34+ marrow cells after the same seven days of culture on a layer of human osteoblasts. The combination (SCF+IL-3+IL-11+TPO) achieved the highest expansion of CD34+CD41+ early megakaryocytic cells from human marrow CD34+ cells reported so far in the literature. Recently, transplantation of SCF+IL-1+IL-3+TPO ex vivo expanded megakaryocytic progenitor cells as a supplement has been shown to accelerate platelet recovery by three to five days in mice. Therefore, the clinical use of the combination (SCF+IL-3+IL-11+TPO) for ex vivo expansion of CD34+ and megakaryocytic progenitor cells from a portion of the donor's marrow harvest is warranted in allogeneic BMT. Such a protocol would accelerate platelet recovery and shorten the period of hospitalization after allogeneic BMT. The present study has confirmed the role of human osteoblasts in supporting the proliferation and maintenance of human CD34+ stem/progenitor marrow cells. Given the facilitating role of osteoblasts shown previously in several allogeneic BMT studies in mice, it is possible to envisage a future role for donor osteoblasts in clinical BMT. Transplantation of the cultured donor osteoblasts together with the ex vivo expanded CD34+ marrow cells as a supplement might not only accelerate platelet recovery but also prevent acute graft-versus-host disease in allogeneic BMT. The present novel culture system should have useful clinical application in allogeneic BMT.     

Induction of anti-idiotypic (ab2) and anti-anti-idiotypic (ab3) antibodies in patients treated with the mouse monoclonal antibody 17-1A (ab1). Relation to the clinical outcome--an important antitumoral effector function?

Forty-three patients with metastatic colorectal carcinoma (CRC) were treated with the unconjugated mouse monoclonal antibody (MAb) 17-1A (ab1) only. The presence of antiidiotypic antibodies (ab2) and anti-antiidiotypic antibodies (ab3) were analyzed using an ELISA technique and a mixed hemadsorption assay respectively. Ninety-five percent (41/43) of the patients developed ab2 both of the IgM and the IgG classes. Forty-seven percent (20/43) of the patients had detectable ab3 after therapy, two of them also before administration of MAb 17-1A. Binding in vitro of ab3 (ab1) to CRC cells could be specifically inhibited by ab1. Ab3 bound to human monoclonal antiidiotypic antibodies and to a goat antiidiotypic antibody (ab2). Both these ab2 were directed against MAb 17-1A (ab1). There was a strong correlation between the presence of ab3 and the clinical outcome. Ab3+ patients survived significantly longer than those who did not develop ab3 antibodies, 80 weeks vs 38 weeks (p less than 0.001). A statistically significant correlation was found between the presence of ab3 and the anti-tumor response (CR + PR + MR + SD) (p = 0.01). Thus, induction of an antiidiotypic cascade seems to be an important antitumor effector function of MAb in the treatment of cancer patients.     

Endogenous gamma interferon-independent host resistance against Listeria monocytogenes infection in CD4+ T cell- and asialo GM1+ cell-depleted mice.

The effects of in vivo administration of antibodies against T-cell subsets and asialo GM1 (ASGM1)-bearing cells on endogenous gamma interferon (IFN-gamma) production and host defense in Listeria monocytogenes-infected mice were investigated. Endogenous IFN-gamma titers in the bloodstreams and spleen extracts of mice on day 2 of infection were partially suppressed by administration of rabbit anti-ASGM1 antibody, but not by anti-CD4 monoclonal antibody (MAb) or anti-CD8 MAb. Of the different combinations of these three antibodies, the most suppressive effect on IFN-gamma production was observed after administration of anti-CD4 Mab and anti-ASGM1 antibody, although anti-CD8 MAb combined with anti-CD4 MAb partially inhibited IFN-gamma production. In contrast, antilisterial resistance was suppressed by the administration of anti-CD8 MAb but not by anti-CD4 MAb or anti-ASGM1 antibody. Antilisterial resistance in mice in which both CD4+ cells and ASGM1+ cells had been depleted was performed as efficiently as in normal mice in spite of the fact that endogenous IFN-gamma production was markedly suppressed. Furthermore, these mice also eliminated L. monocytogenes cells efficiently from the spleens even when they were pretreated with anti-mouse IFN-gamma MAb. These results indicate that CD4+ T cells, CD8+ T cells, and ASGM1+ cells are all responsible for endogenous IFN-gamma production and that antilisterial resistance and endogenous IFN-gamma production are not absolutely correlated.     

Production of anti-CD14 monoclonal antibodies using CD14 expressing COS cells as immunizing antigen

CD14 is a leukocyte surface molecule expressed on monocytes but not on lymphocytes. Recently, CD14 molecule was demonstrated to function as a receptor for endotoxin. CD14 specific monoclonal antibody (MAb), therefore, can be used to identify monocytes and study the host defense mechanism to bacterial endotoxin. To produce MAb against CD14 protein, in this study cDNA encoding CD14 protein and COS cell expression systems were used to prepare CD14 expressing COS cells. The CD14 transfectants were then used as antigen for mouse immunization. The spleen cells of the immunized mouse were then fused with myeloma cells by conventional hybridoma technique. By using this strategy, 5 hybridroma clones secreting antibody specific for CD14 molecule were generated within one fusion. The generated CD14 MAbs were strongly positive with monocytes, weakly positive with neutrophils but negative with lymphocytes. In addition, the generated CD14 MAb blocked the binding of lipopolysaccharide (LPS) to the CD14 molecules. These CD14 MAbs could be used to enumerate peripheral blood monocytes as well as using referent CD14 MAb. We, therefore, introduce an alternative method for preparation of antigen for production of monoclonal antibody. This type of antigen is a very effective antigen for the production of monoclonal antibodies against cell surface molecules.     

Host conditioning with total lymphoid irradiation and antithymocyte globulin prevents graft-versus-host disease: the role of CD1-reactive natural killer T cells.

Our previous studies in mice showed that the nonmyeloablative conditioning regimen of fractionated irradiation of the lymphoid tissues (total lymphoid irradiation; TLI) and depletive anti-T-cell antibodies (anti-thymocyte serum) markedly increased the percentage of regulatory DX5+ and natural killer 1.1+ T cells in the mouse spleen, and prevented acute lethal graft-versus-host disease (GVHD) in BALB/c mice (H-2(d)) following the transplantation of bone marrow (BM) and peripheral blood mononuclear cells (PBMC) from C57BL/6 (H-2(b)) donors. The object of the current study was to determine whether the TLI and anti-thymocyte serum regimen protected natural killer T-cell deficient CD1(-/-) BALB/c mice against GVHD after BM and PBMC transplantation from C57BL/6 donors, and whether a similar conditioning regimen of TLI and anti-thymocyte globulin (ATG) can prevent GVHD in Lewis rat (RT1(l)) hosts after BM and PBMC transplantation from ACI rat (RT1(a)) donors. The experimental results in mice showed that, although wild-type BALB/c hosts are protected in association with a marked increase in CD1- reactive T cells expressing the invariant TCR identified with a CD1 tetramer reagent; CD1(-/-) BALB/c hosts are not. Studies of chimeric donor cells in mice protected from GVHD showed donor T-cell polarization to a Th2 cytokine pattern. Results in rats showed that approximately 1000 fold more donor PBMC cells were required to induce a similar incidence of lethal GVHD in TLI and ATG conditioned hosts as compared with hosts conditioned with single-dose total-body irradiation or total-body irradiation and ATG. Surviving TLI and ATG conditioned rat hosts were complete chimeras. In conclusion, the TLI and ATG/anti-thymocyte serum conditioning regimen protects against GVHD in rats and mice, and regulatory natural killer T cells are required for protection.