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1.
ASTA Z 7557 potentiated the ex vivo efficiency of a T-cell directed immunotoxin containing pokeweed antiviral protein (PAP). We used an immunotoxin of pan-T monoclonal antibody 3-A1 directed against p41 antigen expressed both on normal and leukemic T-cells. Treatment with 3A1-PAP in combination with ASTA Z 7557 produced 7-8 logs elimination of target lymphoblastic leukemia cells. Our data suggest that this new strategy shows potential for more effective ex vivo marrow purging in autologous marrow transplantation for acute lymphoblastic leukemia.  相似文献   
2.
We evaluated a novel ex vivo "purging" protocol for selective elimination of neoplastic T cells from human marrow by using a sensitive clonogenic assay. Immunotoxins (IT) were synthesized by conjugating ricin (R) to four different monoclonal antibodies (MoAb) directed against distinct markers of T cell lineage. Treatment with anti-p67-R produced effective elimination of leukemic T cells from human marrow. The cyclophosphamide congener mafosfamid (ASTA Z 7577) markedly enhanced the target cell cytotoxicity of IT and extended the final level of clonogenic kill 2 to 3 logs. Our data show that anti-p67-R in combination with mafosfamid resulted in a maximum elimination of 6.2 logs of neoplastic T cells with minimal toxicity to normal bone marrow progenitors. The efficiency of this protocol was not reduced in the presence of excess normal bone marrow cells. Similar findings were obtained by using a cocktail of four different anti-T cell IT. This approach is unique in combining both immunologic (IT) and chemical (mafosfamid) strategies for more effective ex vivo bone marrow purging in autologous bone marrow transplantation for T cell acute lymphoblastic leukemia/lymphoblastic lymphoma.  相似文献   
3.
B lymphocyte regulation of human hematopoiesis   总被引:6,自引:0,他引:6  
Epstein Barr virus (EBV)-transformed B lymphoblastoid cell lines (BLCL) were derived from seven different individuals. The ability of BLCL supernatants to stimulate hematopoietic colony formation in vitro was tested in a conventional stem cell assay system. Supernatants promoted the growth of single (GM, E, MK) as well as multi-lineage (GEMM) colonies in bone marrow cultures. Our results indicate that EBV-transformed B lymphocytes produce cytokines that affect in vitro stem cell proliferation and differentiation. These studies demonstrate the regulatory potential of activated B lymphocytes in human hematopoiesis.  相似文献   
4.
The ex vivo anti-leukemic efficacy and stem cell toxicity of two different T cell directed immunotoxins containing pokeweed antiviral protein (PAP) were studied by clonal assays. 5E9-11-PAP, an immunotoxin directed against human transferrin receptors, elicited a maximum leukemic cell kill of 3.9 logs. However, it was also toxic against normal pluripotent stem cells, and therefore is not a clinically useful purgative reagent. PAP conjugated to 3-A1, a monoclonal antibody directed against CD7 (T, p41), was more effective against leukemic T cells than 5E9-11-PAP and eliminated a maximum of 4.8 log of cells. 3A1-PAP was only slightly toxic to pluripotent stem cells: 13% of CFU-GEMM were lost after treatment with 3000 ng of 3A1-PAP/ml, a concentration that eliminated 99.96% of contaminating leukemic T cells from a 200-fold excess of normal bone marrow. Cryopreservation of treated cells by conventional methods did not affect the extreme selectivity and potency of 3A1-PAP. Incubation of 3A1-PAP with peripheral blood mononuclear cells resulted in the complete inhibition of phytohemagglutinin-induced mitogenic response, illustrating the possibility of using this immunotoxin as a potent anti-T cell reagent for prophylaxis against graft vs host disease in allogeneic BMT as well.  相似文献   
5.
In lymphocytes, CD45 regulates the increase in cytoplasmic calcium concentration that occurs after receptor cross-linking. Here we show that T cell receptor complex (CD3/Ti)-mediated inositol phosphate production was inhibited by CD45 ligation in Jurkat cells. CD3/Ti signaling in normal T cells was also inhibited by CD45 ligation, but coupling of CD4 with CD3/Ti gave augmented calcium signals that were entirely resistant to the inhibitory effect of CD45. In contrast, CD3-induced T cell proliferation was suppressed by immobilized CD45 mAb even in the presence of CD4 mAb. The effect of CD45 and CD4 ligation on tyrosine phosphorylation during T cell activation was directly examined by immunoblotting with anti-phosphotyrosine. Using immobilized mAb, CD45 ligation suppressed the tyrosine phosphorylation of specific substrates induced by CD3/Ti stimulation, including almost complete suppression of 150-, 36-, and 35-kDa proteins and partial suppression of 76- and 80-kDa proteins. Other tyrosine-phosphorylated proteins induced by CD3/Ti stimulation, including 135- and 21-kDa proteins, were not suppressed by simultaneous ligation of CD3/Ti and CD45. Simultaneous ligation of CD3 and CD4 enhanced tyrosine phosphorylation of all substrates, but did not overcome the CD45-mediated suppression of tyrosine phosphorylation of the 35- and 36-kDa proteins. The CD45-mediated suppression of phospholipase C activation is therefore modulated by association with CD4 without altering the specific inhibition of tyrosine phosphorylation and T cell proliferation after co-ligation of CD45 and CD3/Ti.  相似文献   
6.
We investigated the role of JAK3 in IgE receptor/FcepsilonRI-mediated mast cell responses. IgE/antigen induced degranulation and mediator release were substantially reduced with Jak3-/- mast cells from JAK3-null mice that were generated by targeted disruption of Jak3 gene in embryonic stem cells. Further, treatment of mast cells with 3'bromo-4'-hydroxylphenyl)-amino-6,7-dimethoxyquinazoline (WHI-P154), a potent inhibitor of JAK3, inhibited degranulation and proinflammatory mediator release after IgE receptor/ FcepsilonRI crosslinking. Thus, JAK3 plays a pivotal role in IgE receptor/ FcepsilonRI-mediated mast cell responses and targeting JAK3 may provide the basis for new and effective treatment as well as prevention programs for mast cell-mediated allergic reactions.  相似文献   
7.
8.
Pokeweed antiviral protein II (PAP-II) is a naturally occurring protein isolated from early summer leaves of the pokeweed plant (Phytolacca americana). PAP-II belongs to a family of ribosome-inactivating proteins which catalytically deadenylate ribosomal and viral RNA. The chemical modification of PAP-II by reductive methylation of its lysine residues significantly improved the crystal quality for X-ray diffraction studies. Hexagonal crystals of the modified PAP-II, with unit cell parameters a = b = 92.51 A, c = 79.05 A, were obtained using 1.8 M Na/K phosphate as the precipitant. These crystals contained one enzyme molecule per asymmetric unit and diffracted up to 2.4 A, when exposed to a synchroton source.  相似文献   
9.
The objective of this study was to develop a nontoxic and noncontraceptive vaginal drug delivery vehicle for lipophilic anti-human immunodeficiency virus (HIV) microbicides. Three representative poorly water-soluble novel broad-spectrum anti-HIV microbicides, PHI-113, PHI-346, and PHI-443, were evaluated in 11 different solvent systems. Based on their solubility profiles, a novel non-spermicidal self-emulsifying gel (viz Conceival) composed of pharmaceutical excipients, sorbitol, polyethylene glycol 400, polysorbate 80, microcrystalline cellulose, xanthan gum, and water was optimized. Conceival enhanced the solubility of these poorly water-soluble (<0.001 mg/mL) anti-HIV drugs by at least 150- to 270-fold. Conceival was evaluated in vivo in the New Zealand white rabbit model for the preservation of sperm function based on pregnancy outcome and the potential for vaginal irritation following single and multiple intravaginal applications, respectively. Conceival administered intravaginally immediately prior to artificial insemination with semen had no adverse effects on subsequent reproductive performance, neonatal survival, or pup development when compared with untreated control group. Histologic evaluation of vaginal tissues of rabbits exposed intravaginally to Conceival for 14 consecutive days revealed lack of epithelial, submucosal, and vascular changes at the gel application site (total irritation score <3 out of a possible 16). These findings indicate that Conceival has potential to become a clinically useful, safe noncontraceptive vaginal vehicle for lipophilic microbicides. Published: September 20, 2005  相似文献   
10.
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