Therapeutic immunology最新文献

This study was designed to demonstrate the efficacy in animals of a ricin antitoxin consisting of purified avian antibodies. Antitoxins consisting of avian antibodies have significant advantages when compared to conventional mammalian (e.g. horse) antibodies; (a) avian antibodies do not fix human complement, eliminating associated inflammatory reactions, and, (b) avian antibodies can be manufactured more economically. Ricin toxoid was injected into laying hens followed by collection of eggs bearing hyperimmune immunoglobulin. Immunoglobulin was extracted from yolks and purified by immunoaffinity chromatography. In a mouse model for toxin neutralization it was shown that immunoaffinity purified ricin antibodies could prevent ricin lethality. Furthermore, it was shown that passive antibody treatment leads to active ricin immunization in animals given lethal ricin doses. Highly purified avian antibodies, as developed in this study, should offer enhanced clinical effectiveness, greater safety, and reduced manufacturing costs when compared to other technologies.

A number of models of spontaneous chronic intestinal inflammation in mice and rats have recently been developed. A characteristic of the majority of these models is that disease developed as a consequence of immune manipulations, suggesting a central role for the immune system in the regulation of intestinal inflammation. Analysis of cytokine patterns in disease showed elevations in TNF-alpha and IFN-gamma, characteristic of the T-helper-1 (Th1) pathway, implicating Th1 cells and their cytokines in disease pathogenesis. Strikingly, inflammation did not develop in mice maintained in germ-free conditions, suggesting disease may develop due to a dysregulated inflammatory response to components of the normal flora. Evidence from a number of these models suggests that this potentially pathogenic inflammatory response does not develop in normal animals as it is actively inhibited by a population of CD4+ alpha beta + regulatory T cells and immunosuppressive cytokines such as IL-10 and TGF-beta 1. These new models will allow further investigation into the mechanisms of natural immune regulation and protection in the intestinal tract and how these mechanisms relate to the etiopathogenesis of inflammatory bowel disease (IBD). Furthermore, these models should provide useful insights for the design of effective immunomodulatory therapies for the treatment of IBD in humans.

The control of tuberculosis has become more elusive with the increased incidence of HIV, and the continued selection of multidrug-resistant organisms. The intracellular pathogenesis of, and host-response to Mycobacterium tuberculosis present challenges to both classical chemotherapeutic and vaccination approaches, with the organism able to replicate in an unrestricted manner in lung but not other tissues. Adequate control of this pathogen, that has evolved so successfully for its symbiotic exploitation of man, will require complex approaches including additional chemotherapeutics of more acceptable toxicity and efficacy, vaccination and commitment to public health measures. In this review, the worldwide scope of the disease is outlined, and its direct and indirect costs considered. The organism enjoys the protective advantages of a slow replication and of a specialized phagolysosomal intracellular niche, requiring a host-response capable of breaching these cellular barriers. The challenges of current vaccine approaches, including live vaccines, target antigen selection and the antigen delivery and adjuventation necessary to elicit adequate pulmonary responses are discussed. Our current understanding is inadequate to control TB and the rekindling of fundamental experimental approaches to the organism, and the host response it evokes, are essential to generate the preventative and therapeutic means necessary for its worldwide control.

The expression of cytokine receptors by a variety of solid tumour tissues was examined, using an immunofluorescence procedure optimized for sensitivity. Several cytokines generally considered as relevant only to the immune and haematopoietic systems were shown to be expressed by solid tumours. For example, breast carcinoma frequently expressed both chains of the IL-3 receptor, the beta chain of the IL-2 receptor, the TNF type two receptor, the signal-transducing chain CD130, and c-kit. The broad expression of cytokine receptors suggests that the receptor profile of individual tumours should be determined before the application of therapy that involves the administration of cytokines.

The number of high quality crystal structures of antibody fragments available in the Brookhaven Protein Data Bank is rapidly increasing. These structures provide a substantial knowledge base and support model building of novel antibody combining sites. We review some basic principles of antibody structure, describe structure-based modelling procedures, and indicate the strengths and weaknesses of the modelling approach. Applications of antibody models are discussed.

Tumour necrosis factor (TNF) is an important mediator of immune and inflammatory responses and has been recognized as a major pathogenic factor in several autoimmune and inflammatory diseases. TNF receptor TR60 plays a critical role in signalling the pathogenic activities of TNF. We here describe molecular cloning and bacterial production of a single-chain antibody (scFv H398) directed against TR60 which possesses antagonistic activity. VH and VL encoding sequences were isolated by PCR from the murine hybridoma cell line H398, cloned into a scFv expression vector and expressed in Escherichia coli. The recombinant antibody (Ab) fragment was found as an active soluble protein in the periplasm but also formed inclusion bodies. Re-folded scFv H398 purified from inclusion bodies was shown to be functional and stable at 37 degrees C with a half-life of 50 h. Comparison of the antigen binding characteristics of scFv with the parental enzymatically produced Fab H398 revealed that both Ab fragments have the same epitope specificity and an identical antigen binding affinity of 1.5 nM. In an in vitro assay it was demonstrated that scFv H398 is an efficient inhibitor of TNF mediated cytotoxicity with an IC50 of 22 nM, which is comparable to the antagonistic activity of natural Fab H398 with an IC50 of 12 nM. As scFv H398 possesses the high affinity TR60 binding and receptor antagonistic activity of the parental Ab H398 but is expected to be less antigenic in man, it provides a valuable tool for the development of novel therapeutic reagents against TNF mediated diseases.

Natural killer (NK) activity was assayed in fresh peripheral blood mononuclear cells (PBMs) from cancer patients receiving interferon (IFN)-beta ser. Patients received a single intravenous injection of IFN-beta ser (90 x 10(6) IU m-2) on alternate days for 2 weeks, followed by a higher dose (180 x 10(6) IU m-2) on the same schedule. PBM NK lysis of K562 target cells was significantly increased in PBMs sampled 24 h after the initial injection (P < 0.05). At the end of the first 2 weeks of the protocol, NK cytotoxic activity of PBMs had fallen below the original baseline levels; the higher IFN dose subsequently given was without effect. However, significant increases in the proportion of CD16+ cells were seen following each injection. A positive correlation was also seen between the increased lytic activity of CD16+ NK cells and the proportion of CD38+ NK cells, but not the proportion of CD56+ NK cells. In vitro IFN-treatment of these in vivo-treated PBMs resulted in a further increase in NK activity. Pre-exposure in vivo to IFN-beta ser seems to prime the PBMs to respond to in vitro stimulation by IFN-gamma, which otherwise had no effect. Phenotypic analysis of PBMs after in vitro exposure to IFN-beta ser showed that the levels of CD16+, CD38+ and CD56+ cells did not change. All the NK activity responding to IFN-beta ser was found in the CD16+ enriched population of PBM, suggesting that it is unlikely that in vivo redistribution of CD16+ subsets representative of NK cells has occurred in the peripheral blood.

Aim: The risk of developing melanoma, the natural history of this disease, and the response to therapy with biological reagents may be determined, in part, by a patient's human leukocyte antigen (HLA) phenotype. In order to study this, the relationship between HLA type and clinical response to therapy with interleukin-2 (IL-2) was evaluated.

Methods: We retrospectively determined the HLA phenotype of 82 patients with metastatic melanoma who were treated with IL-2-based therapy. Fresh or frozen lymphocytes were serologically typed by standard lymphocytotoxicity techniques (NIH or Amos modified). The treatment regimens included IL-2 alone or with tumour infiltrating lymphocytes, lymphokine activated killer cells, cyclophosphamide, interferon-alpha, and tumour necrosis factor-alpha. Initially, the relationship between clinical response and each HLA antigen was evaluated by performing a two-tailed Fisher exact test. Associations with a P-value less than or equal to 0.10 without adjustment for multiple comparisons were considered worthy of further study. Independent confirmation of these apparent associations was obtained by studying the relationship between HLA phenotype and patient survival using Cox proportional hazards models.

Results: In the initial screening, a statistically significant association between clinical response and the expression of HLA-DQ1 was observed (unadjusted P2 = 0.0017). HLA-DQ1 was also independently associated with prolonged survival (P2 = 0.026). This positive association with survival was evident both for patients who responded to therapy and those who did not respond, as defined by > 50% tumour regression.

Conclusions: Among patients with metastatic melanoma, HLA-DQ1 appears to be associated with clinical response to therapy using IL-2. This apparent association is confirmed by the observation that HLA-DQ1 is independently associated with prolonged survival in this group of patients.

Immunoassays for the measurement of human anti-immunoglobulin responses against the CD45 specific rat monoclonals, YTH 24.5 and YTH 54.12, have been developed. The assays are based on a 'double antigen' ELISA system and are reproducible with coefficients of variation of less than 15%. The assays were used to measure anti-immunoglobulin responses in sera from 40 patients who had received kidneys pre-treated with the pair of anti-CD45 monoclonals YTH 24.5 and YTH 54.12. Only two patients elicited a weak human antimurine antibody (HAMA) response.