Molecular heterogeneity of benzodiazepine receptors

Benzodiazepines exhibit reversible, stereospecific high affinity binding to mammalian brain membranes, and the respective binding sites for 3H-flunitrazepam represent pharmacologically and clinically relevant receptors for benzodiazepines. Recently it has been demonstrated that reversibly bound 3H-flunitrazepam becomes irreversibly attached to a specific membrane protein with apparent molecular weight of 50,000 when incubations are performed in the presence of UV light. Irreversible binding of 3H-flunitrazepam to this protein had pharmacological properties similar to reversible benzodiazepine receptor binding, indicating that 3H-flunitrazepam is a photoaffinity label for the benzodiazepine receptor. Using irreversible binding of 3H-flunitrazepam and subsequent electrophoretic separation of the labelled proteins in SDS-gels followed by fluorography, we found that in hippocampus and several other brain regions at least two different types of benzodiazepine receptors exist. Each seems to be associated with a gamma-aminobutyric acid (GABA) receptor.     

Detection of P-glycoprotein in multidrug-resistant cell lines by monoclonal antibodies

One reason for the failure of chemotherapy in the treatment of advanced cancers may be the outgrowth of multidrug-resistant tumour cells. Multidrug resistance has been modelled in numerous mammalian cell lines in which the phenotype is characterized by a pleiotropic cross-resistance to unrelated drugs. In the study reported here, we have produced monoclonal antibodies whose binding to plasma membranes of different multidrug-resistant mammalian cells correlates with the degree of drug resistance. All these antibodies are specific for P-glycoprotein, a cell surface component of relative molecular mass (Mr) 170,000 (170K) that has been described previously, and are directed against three spatially distinct epitopes which define a conserved cytoplasmic domain in the C-terminal region of the P-glycoprotein polypeptide. The conserved nature of P-glycoprotein and its low-level expression is drug-sensitive cells suggest that it has an important function at the cell surface. The monoclonal antibodies against P-glycoprotein described here might serve as diagnostic reagents for clinically unresponsive tumours.     

Therapy with monoclonal antibodies by elimination of T-cell subsets in vivo

A major aim in immunology has been to understand how the immune system evokes characteristic responses to infection, foreign tissue grafts and tumours. The current view of immunoregulation is based mainly on studies of lymphocyte subsets, either in vitro or by adoptive transfer to irradiated recipients. Many reagents are available for defining T-cell subsets, but only recently have there been helper T-cell-specific antibodies against the mouse equivalent of the Leu3/T4 (man) and W3/25 (rat) antigens. It is clear that monoclonal antibodies will eventually replace antilymphocyte globulin for immunosuppression in organ grafting, but although there has been some clinical success, most monoclonal reagents cause only transient reductions in their target cells in vivo. This uncertainty in the potency of monoclonal antibodies has led some workers to consider them as targeting agents for such highly cytotoxic drugs as ricin A (ref. 21). We show here that unmodified monoclonal antibodies can be extremely effective at depleting cells in vivo and can be used for the selective manipulation of different aspects of the immune response.     

人白血病抑制因子（hLIF）单克隆抗体的制备与鉴定

 为了获得抗人白血病抑制因子（hLIF）单克隆抗体,以重组hLIF蛋白为抗原,免疫Balb/c小鼠,采用传统的小细胞融合、无限稀释法制备了10株杂交瘤的腹水hLIF抗体,并对腹水进行了纯化.腹水粗品抗体经rProteinA一步亲和层析法纯化和鉴定后,抗体分子量都符合抗体的特性,抗体的纯度都达到了96.6%以上,抗体亲和常数在1.89×10-9~1.51×10-12mol/L,其中1B8a、5C1b、5G4a细胞株制备的抗体属于高亲和力抗体,可以对其的应用进行进一步的研究和探讨.     

Inhibition of P. falciparum growth in human erythrocytes by monoclonal antibodies

Malaria is increasing in incidence and prevalence in most tropical areas and is a major problem for both individuals and communities. Current malaria research is aimed at developing vaccines and, for this, it may be useful to define Plasmodium antigen(s) related to the development of a protective immune response in the host. Monoclonal antibodies have recently been shown to interfere with rodent malaria infection (Plasmodium berghei) at the sporozoite or merozoite stage. We have now raised monoclonal antibodies against single antigenic determinant(s) of Plasmodium falciparum and report that some of them inhibit the growth of erythrocytic forms of P. falciparum in vitro.     

Different forms of p53 detected by monoclonal antibodies in non-dividing and dividing lymphocytes

The commitment of non-dividing cells (in G0) to enter division can be studied using primary cultures of lymphocytes. The cells are stable in G0 unless stimulated by mitogen such as concanavalin A (Con A). Commitment to enter the division cycle depends on the expression of gene(s) induced by Con A and the synthesis of p53 protein correlates with this commitment step. I show here that in unstimulated cells, a second form of p53 is synthesized and is restricted to G0.