Compartmentalized immune responses: antigen-specificity of cerebrospinal fluid T-cell lines maintained in the absence of antigen

The generation of long-term interleukin 2-dependent T-cell lines from anatomically compartmentalized sites of pathology offers a unique approach to the investigation of certain autoimmune diseases. However, it is generally believed that antigen-specific T-cell lines and clones lose antigen reactivity and specificity when propagated in the absence of antigen. Therefore, the optimal application of this approach to such diseases in which the pathogenetic antigens are unknown may be difficult. In approaching this problem, we have recently demonstrated that a proportion of antigen-specific T-cell lines derived from the peripheral circulation can maintain antigen specificity if propagated with antigen-presenting cells alone or with antigen-presenting cells together with OKT3 antibody, but in either case in the absence of antigen. In this report we describe the use of this approach to maintain the antigen specificity of T cells obtained from an anatomically compartmentalized site of pathology--the cerebrospinal fluid from a patient with tuberculous meningitis. We report here that a proportion of the T-cell lines generated from such cerebrospinal fluid lymphocytes can be maintained as antigen specific in the absence of antigen if propagated with either antigen-presenting cells alone or with antigen-presenting cells and OKT3 antibody. The approach illustrated in this report should now find broad applicability in the investigation of a number of autoimmune disease.     

Mucosal immunization with PLGA-microencapsulated DNA primes a SIV-specific CTL response revealed by boosting with cognate recombinant modified vaccinia virus Ankara

Systemically administered DNA encoding a recombinant human immunodeficiency virus (HIV) derived immunogen effectively primes a cytotoxic T lymphocyte (CTL) response in macaques. In this further pilot study we have evaluated mucosal delivery of DNA as an alternative priming strategy. Plasmid DNA, pTH.HW, encoding a multi-CTL epitope gene, was incorporated into poly(D,L-lactic-co-glycolic acid) microparticles of less than 10 microm in diameter. Five intrarectal immunizations failed to stimulate a circulating vaccine-specific CTL response in 2 Mamu-A*01(+) rhesus macaques. However, 1 week after intradermal immunization with a cognate modified vaccinia virus Ankara vaccine MVA.HW, CTL responses were detected in both animals that persisted until analysis postmortem, 12 weeks after the final boost. In contrast, a weaker and less durable response was seen in an animal vaccinated with the MVA construct alone. Analysis of lymphoid tissues revealed a disseminated CTL response in peripheral and regional lymph nodes but not the spleen of both mucosally primed animals.     

Adjuvant-dependent modulation of Th1 and Th2 responses to immunization with beta-amyloid

The role of adjuvant on the T(h)1 and T(h)2 immune responses to Abeta-immunotherapy (Abeta(42 )peptide) was examined in wild-type mice. Fine epitope analysis with overlapping oligomers of the Abeta(42) sequence identified the 1-15 region as a dominant B cell epitope. The 6-20 peptide was recognized only weakly by antisera from mice administrated with Abeta(42) peptide formulated in complete Freund's adjuvant (CFA), alum or TiterMax Gold (TMG). However, mice immunized with Abeta(42) mixed with QS21 induced a significant antibody response to the 6-20 peptide. The only T cell epitope found was within the 6-28 sequence of Abeta(42). QS21 and CFA induced the strongest humoral response to Abeta, alum was intermediate, and TMG the weakest adjuvant. Analysis of antibody isotypes specific for Abeta indicates that alum induces primarily T(h)2-type immune response, whereas TMG, CFA and QS21 shift the immune responses toward a T(h)1 phenotype. Stimulation of splenocytes from Abeta-immunized mice with Abeta(40) peptide induced strikingly different cytokine expression profiles. QS21 and CFA induced significant IFN-gamma, IL-4 and tumor necrosis factor-alpha expression, whereas alum induced primarily IL-4 production. As T(h)1-type immune responses have been implicated in many autoimmune disorders, whereas T(h)2-type responses have been shown to inhibit autoimmune disease, the choice of adjuvant may be critical for the design of a safe and effective immunotherapy for Alzheimer's disease.     

Baf60c is a component of the neural progenitor-specific BAF complex in developing retina

Remodeling of the chromatin network plays an important role regulating embryonic development as well as differentiation. The SWI/SNF complex is an ATP-dependent chromatin-remodeling complex. It consists of several proteins, including an ATPase subunit, either Brg1 or Brm. Two subunits of this complex, Baf53a and Baf45, have been previously identified as being neural progenitor-specific. In this study, we show that Baf60c, another important part of this large complex, acts in a similar neural progenitor-specific manner. We show that during development Baf60c is expressed in neural progenitors in human retinas as well as mouse retina, cortex and spinal cord. Baf60c expression is lost during neural differentiation and its overexpression keeps the progenitors in a proliferative state through its interaction with the Notch pathway. Finally, we show that Baf60c is re-expressed in the Müller glial cells that re-enter the cell cycle after neurotoxic damage.     

Clamp loading,unloading and intrinsic stability of the PCNA, β and gp45 sliding clamps of human,E. coli and T4 replicases

Background: The high speed and processivity of replicative DNA polymerases reside in a processivity factor which has been shown to be a ring-shaped protein. This protein (‘sliding clamp’) encircles DNA and tethers the catalytic unit to the template. Although in eukaryotic, prokaryotic and bacteriophage-T4 systems, the processivity factors are ring-shaped, they assume different oligomeric states. The Escherichia coli clamp (the β subunit) is active as a dimer while the eukaryotic and T4 phage clamps (PCNA and gp45, respectively) are active as trimers. The clamp can not assemble itself on DNA. Instead, a protein complex known as a clamp loader utilizes ATP to assemble the ring around the primer-template. This study compares properties of the human PCNA clamp with those of E. coli and T4 phage. Results: The PCNA ring is a stable trimer down to a concentration below 100 nm (K_d ≈ 21 nm ). On DNA, the PCNA clamp slides freely and dissociates from DNA slowly (t_1/2 ≈ 24 min). β is more stable in solution (K_d < 60 pm ) and on DNA (t_1/2 ≈ 1 h) than PCNA which may be explained by its simpler oligomeric state. The T4 gp45 clamp is a much less stable trimer than PCNA (K_d ≈ 250 nm ) and requires association with the polymerase to stabilize it on DNA as observed previously. The consequence of this cooperation between clamp and polymerase is that upon finishing a template and dissociation of the polymerase from DNA, the gp45 clamp spontaneously dissociates from DNA without assistance. However, the greater stability of the PCNA and β clamps on DNA necessitates an active process for their removal. The clamp loaders (RF-C and γ complex) were also capable of unloading their respective clamps from DNA in the presence of ATP. Conclusions: The stability of the different clamps in solution correlates with their stability on DNA. Thus, the low stability of the T4 clamp explains the inability to isolate gp45 on DNA. The stability of the PCNA and β clamps predicts they will require an unloading factor to recycle them on and off DNA during replication. The clamp loaders of PCNA and β double as clamp unloaders presumably for the purpose of clamp recycling.     

Autocrine growth of human blymphocytes: Maintained response to autostimulatory factors is the special feature of immortalization by Epstein-Barr virus—A hypothesis

The autocrine growth profile of human B lymphocytes transformed with Epstein-Barr virus (EBV) was found to comprise three distinct components: a B-cell growth factor (BCGF); an interleukin-1 (IL-1)-like activity; an activity requiring cell-to-cell contact for its action. Observations on the inhibition of the EBV-carrying Daudi lymphoma line by α-interferon indicated that loss of response to these autostimulatory factors was underlying growth cessation. Furthermore, a putative for BCGF was found to be down-regulated on B cells stimulated with non-transforming mitogens but constitutively expressed following EBV-transformation. Taken together with recent evidence that normal B cells produce autostimulatory factors, these findings suggest that the special feature of autocrine growth by EBV-immortalized cells is a maintenance of what should normally be a transient phenotype, possibly through deregulation of receptor expression. This hypothesis is discussed.     

Animal models and treatment of prostate cancer

Model systems for prostate cancer in rats have been developed and used for investigations on tumor biology and therapy. The "Pollard tumors" provide a combination of in vitro and in vivo attributes by which investigations can be directed at local tumor development and spontaneous metastasis. The evolution and early applications of this model system are reviewed, and the therapeutic benefits of delayed release of cyclophosphamide are presented.     

Psycho-Behavioural Segmentation in Food and Nutrition: A Systematic Scoping Review of the Literature

Inadequate dietary intakes are a key modifiable risk factor to reduce the risk of developing non-communicable diseases. To encourage healthy eating and behaviour change, innovative public health interventions are required. Social marketing, in particular segmentation, can be used to understand and target specific population groups. However, segmentation often uses demographic factors, ignoring the reasons behind why people behave the way they do. This review aims to explore the food and nutrition related research that has utilised psycho-behavioural segmentation. Six databases from were searched in June 2020. Inclusion criteria were: published 2010 onwards, segmentation by psycho-behavioural variables, outcome related to food or nutrition, and healthy adult population over 18 years. 30 studies were included; most were quantitative (n = 28) and all studies used post-hoc segmentation methods, with the tools used to segment the population varying. None of the segments generated were targeted in future research. Psycho-behavioural factors are key in understanding people’s behaviour. However, when used in post-hoc segmentation, do not allow for effective targeting as there is no prior understanding of behaviours that need to change within each segment. In future, we should move towards hybrid segmentation to assist with the design of interventions that target behaviours such as healthy eating.