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The ability of firefighting vehicles and staff to reach a fire area as quickly as possible is critical in fighting against forest fires. In this study, a Geographical Information System-based decision support system was developed to assist fire managers in determining the fastest and the safest or more reliable access routes from firefighting headquarters to fire areas. The decision support system was tested in the Kahramanmaras Forestry Regional Directoratein the Mediterranean region of Turkey. The study area consisted of forested lands which had been classified according to fire sensitivity. The fire response routing simulations considered firefighting teams located in 20 firefighting headquarter locations. The road network, the locations of the firefighting headquarters, and possible fire locations were mapped for simulation analysis. In alternative application simulations, inaccessible roads which might be closed due to fire or other reasons were indicated in the network analysis so that the optimum route was not only the fastest but also the safest and most reliable path. The selection of which firefighting headquarters to use was evaluated by considering critical response time to potential fire areas based on fire sensitivity levels. Results indicated that new firefighting headquarters should be established in the region in order to provide sufficient firefighting response to all forested lands. In addition, building new fire access roads and increasing the design speed on current roads could also increase firefighting response capabilities within the study area.

Microglia exist under physiological conditions in a resting state but become activated after neuronal injury. Recent studies have highlighted the reciprocal role of neurons in controlling both the number and activity of microglia. In this study, microglia derived from newborn rat cortices were cultured and activated by interferon-gamma (IFNgamma) treatment, then exposed to recombinant Sema3A or conditioned medium derived from stressed embryonic cortical neurons. We found that activation of microglia by IFNgamma induced differential upregulation of the semaphorin receptors Plexin-A1 and Neuropilin-1. This result was confirmed by Northern blotting, reverse transcription-PCR, and Western blotting. Furthermore, recombinant Sema3A induced apoptosis of microglia when added to the in vitro culture, and a similar result was obtained on activated microglia when Sema3A was produced by stressed neurons. Using an in vivo model of microglia activation by striatal injection of lipopolysaccharide demonstrated a corresponding upregulation of Plexin-A1 and Neuropilin-1 in activated microglia and enhanced production of Sema3A by stressed adult neurons. These results suggest a novel semaphorin-mediated mechanism of neuroprotection whereby stressed neurons can protect themselves from further damage by activated microglia.

We use spatial data representing transportation networks, elevation, stand height, and recreation use to construct and compare models of recreation use patterns and visibility in a forest. The recreation use pattern model depicts use frequencies along travel corridors. The visibility model quantifies visibility for all forest areas. We find that the models provide different but complementary types of information. Forest managers who are involved in scheduling harvest operations and want to address the visual concerns of forest visitors may benefit most from the visibility model. Managers who wish to know more about travel patterns or to reroute forest visitors affected by operations may benefit from the use pattern model. A combination of the two models has the highest potential for providing planning assistance in multiple-use forests. Both models may be able to enhance visual resource management (VRM) systems already in use by providing spatially explicit recreation use and visibility data.

We describe the engineering of antibody fragments produced in bacteria for recruitment of complement effector functions. From a phage display repertoire we isolated human antibody fragments directed against complement C1q, and linked these to lysozyme-specific antibody fragments, creating bispecific antibodies (diabodies). One diabody was able to recruit C1q, resulting in efficient lysis of lysozyme-coated sheep erythrocytes, and also induced rosette-formation of erythrocytes with human monocytes and phagocytosis after phorbol ester stimulation. These diabodies may have therapeutic applications requiring the activation of complement.

The administration of the immunosuppressive humanized monoclonal antibody CAMPATH 1-H, which recognizes CD52 on lymphocytes and monocytes, is associated with a first-dose cytokine-release syndrome involving TNFalpha, IFNgamma, and IL-6 clinically. In vitro models have been used to establish the cellular source and mechanism responsible for cytokine release, demonstrating that cytokine release is isotype dependent, with the rat IgG2b and human IgG1 isotype inducing the highest levels of cytokine release, which was inhibited with antibody to CD16, the low affinity Fc-receptor for IgG (FcgammaR). Cross-linking antibody opsonized CD4 T lymphocytes failed to stimulate TNFalpha release, which together with the observation that TNFalpha release by purified natural killer (NK) cells stimulated by fixed autologous CAMPATH 1-H-opsonized targets was inhibited with anti-CD16, indicates that cytokine release results from ligation of CD16 on the NK cells, rather than Fc-receptor (FcR)-dependent cross-linking of CD52 on the targeted cell. Since the hierarchy of isotypes inducing cytokine release in these cultures matches that seen clinically, we conclude that ligation of CD16 on NK cells is also responsible for cytokine release after injection of CAMPATH 1-H in vivo.

It is traditionally held that human IgG4 MoAbs should not deplete target cells in vivo, as this isotype is inactive in a number of in vitro assays that measure effector function. We have previously challenged this dogma, and the current study was designed to investigate the in vivo biological effects in humans of a MoAb of human IgG4 isotype. Nine patients with refractory rheumatoid arthritis (RA) fulfilling ARA criteria, and one with ankylosing spondylitis (AS) received a human IgG4 Campath-1 MoAb (with specificity against the pan-lymphocyte antigen CD52) as part of a two-stage therapeutic protocol. In stage 1, patients received a single dose of this MoAb. Stage 2, starting 48 h later, comprised a 5-day course of a human IgG1 Campath-1 MoAb with identical V-region (CAMPATH-1H), as previously used in the management of RA patients. The intervening 48 h provided a window of opportunity to monitor the biological effects of the IgG4 MoAb for comparison with the IgG1. The two MoAbs were also compared for in vitro biological activity. IgG4 depleted peripheral blood lymphocytes (PBL), albeit less efficiently than IgG1. It produced a first-dose reaction of similar intensity, although associated circulating tumour necrosis factor-alpha (TNF-alpha) levels were lower. TNF-alpha release from whole blood in vitro was also greater with the IgG1 MoAb. The study design did not permit conclusions to be drawn regarding therapeutic efficacy of the IgG4 MoAb. In summary, a human IgG4 Campath-1 MoAb depletes target cells in vivo. Importantly, this study demonstrates for the first time in humans that in vitro assays may not predict the in vivo effector function of therapeutic MoAbs.

Rat oligodendrocytes, which activate the classical pathway of complement in the absence of antibody, are highly sensitive in a reactive lysis assay using human C5b6 and EDTA serum. Oligodendrocytes may be relatively deficient in glycolipid-linked complement regulatory protein(s), since digestion with phosphatidylinositol-specific phospholipase C (PI-PLC) failed to increase their sensitivity to serum, whereas complement-insensitive astrocytes, when treated with PI-PLC, became strikingly sensitive. To test the hypothesis that oligodendrocytes lack terminal complement regulatory molecule(s), human erythrocyte CD59, a recently described complement regulatory protein, was purified to homogeneity. The biological activity of the preparation was confirmed by reincorporating the protein into guinea-pig erythrocytes through its glycolipid anchor, which resulted in dose-dependent protection against human C5b6 and EDTA serum. Incorporation of 10(5) molecules of human CD59 into rat oligodendrocytes resulted in good protection against homologous human complement (76%), and significant protection against rat complement homologous to the cell (36%). Protection could be reversed using an antibody to CD59.

This paper describes a T-cell targeting strategy based on the use of an antigen-monoclonal antibody heteroconjugate. A rat anti-idiotypic monoclonal antibody specific for a murine B-cell lymphoma was conjugated to the purified protein derivative (PPD) of tuberculin. This construct selectively delivered up to 4.5 x 10(4) molecules of PPD onto each tumour cell. Targeted PPD was internalized for endosomal processing and was presented in association with the I-A class II restriction element to PPD-reactive T-helper (Th) cells. Activated Th cells were demonstrated to proliferate and secrete significant levels of tumour necrosis factor (TNF). Such lymphokine secretion was observed at a PPD concentration as low as 1 ng/ml. Despite the secretion of TNF, the B-cell lymphoma was found to be resistant to autonomous Th-mediated cytotoxicity. Targeted Th cells did, however, activate tumourcidal macrophages that subsequently mediated significant tumour cytostasis. Based on this observation, it is proposed that the targeting system described may be exploited as the basis for a future immunotherapeutic strategy.

We have shown that a murine CD4+ PPD-reactive T lymphocyte clone was weakly cytotoxic towards the syngeneic tumour B16 melanoma and MC6A fibrosarcoma which had been coated with PPD using a monoclonal antibody-PPD heteroconjugate. Cell-free supernatants produced by PPD-stimulated T lymphocyte clones were however highly cytostatic for the two tumour targets when assayed over 48-72 h. In this study we have demonstrated good titres of tumour necrosis factor (TNF) and interferon-gamma (IFN-gamma) in the supernatants, which accounted for their observed cytostatic activity on the tumour targets. The high level of cytostasis seen with the B16 melanoma using the supernatants could be attributed to their sensitivity to the cytostatic activity of IFN-gamma; the lower levels of cytostasis seen with the IFN-gamma-resistant MC6A target was the result of IFN-gamma increasing the sensitivity of this target to TNF. Antibodies to IFN-gamma were able to neutralize the majority of the cytostatic activity of the supernatants on both targets, consistent with the role demonstrated for this lymphokine.

We have constructed PPD monoclonal antibody heteroconjugates specific for a tumour-associated antigen of C57BL/6 melanomas or for human complement component C3d fixed de novo to murine fibrosarcoma cells (MC6A). The ability of our heteroconjugates to target CD4+ PPD-reactive T cells against the appropriate tumour targets was then determined in vitro. Heteroconjugate-treated B16-F10 and MC6A tumour targets were both able to present PPD to the specific T cells, resulting in activation and concomitant lymphokine secretion. Secreted lymphokines were then demonstrated to cause significant tumour cytolysis and cytostasis in vitro. Preliminary experiments in vivo suggest that this targeting system may provide the basis for a future immunotherapeutic strategy.

Cryosurgery and excision were used to treat primary tumours of HSV-2-transformed hamster tumour sublines, and post-operative survival and the extent of metastatic disease were compared in the two groups. An inferior prognosis was observed following cryosurgery although the extent of metastatic disease was similar in both groups. Using this model it would appear that cryosurgery enhances the development of micrometastases rather than affecting the number of cells shed from the primary tumour during surgery. To investigate the underlying causes of the decrease in survival following cryosurgery, in vitro assays were used to monitor host immunocompetence following surgery. The results showed that whilst natural killer cell cytotoxicity was only marginally depressed, mitogen responsiveness and lymphocyte participation in a mixed lymphocyte reaction were severely reduced 3-7 days post-cryosurgery. In parallel with immunosuppression, extensive cell proliferation in the spleen of cryosurgically treated tumour-bearing animals was observed. Histological examination of the spleen demonstrated the presence of large numbers of transformed cells which correlated with the loss of mitogen responsiveness and the ability to participate in a mixed lymphocyte reaction. Further studies (manuscript submitted for publication) have demonstrated that spleen cells from animals whose tumour is treated by cryosurgery are capable of suppressing immunocompetence in vitro, implying they have a role in the uncontrolled growth of micrometastases in vivo.

Cryosurgery of a primary HSV-2-induced hamster fibrosarcoma resulted in the generation of a population of suppressor cells. These cells were detectable in the spleen 1-10 days post-cryosurgery by their ability to suppress the proliferation of immunocompetent splenic T-lymphocytes following exposure to concanavalin A (Con A). The spleens of tumour-bearing (t.b.) animals which received cryosurgery 3 days previously displayed gross splenomegaly due to the generation of large numbers of highly proliferative erythroblasts. The erythroblast cells were unlikely to be the source of suppression since time course studies have demonstrated the presence of suppressor cells before and after their appearance in the spleen. The erythroblasts therefore probably reflected a response by the host to regenerate the erythrocytes lost during surgery and their presence was independent of the appearance of suppressor cells. Characterisation of the suppressor cell has revealed it to be non-adherent and esterase negative making it unlikely to be of macrophage (MO) lineage. This was confirmed by the ability of splenic MOs from day 3 t.b. cryosurgery-treated animals to completely restore Con A-dependent T-lymphocyte proliferation following MO depletion. As nylonwool column-eluted cells are able to suppress Con A-dependent T-lymphocyte proliferation, it seemed unlikely that B-lymphocytes play a role in cryosurgery-induced immunosuppression. These findings suggest that cryosurgery of a t.b. animal results in the generation of a population of T-lymphocytes capable of suppressing Con A-dependent T-lymphocyte proliferation, and infers that these cells contribute to the inferior prognosis following cryosurgery as compared to excision of a metastatic tumour.