Ten year maturation period in a level-I trauma center, a cohort comparison study.

PURPOSE: Many changes have been made to improve trauma care. Improved trauma team response and usage of a hybrid resuscitation room are examples of how this trauma center has developed. The aim was to assess how the outcome of the trauma population was influenced by the maturation. METHODS: A cohort comparison, between June 2004-July 2005 and 2014, was performed. All adult trauma patients with an Injury Severity Score (ISS) >15 were included. Variables collected were: patient demographics, mechanism of trauma, total prehospital time, pre- and inhospital trauma scores, vital signs, blood values and interventions, and physician staffed helicopter emergency medical services (P-HEMS) involvement and outcome. RESULTS: From June 2004 to July 2005 219, patients were admitted, and for the year 2014, this was 282 patients. The 2014 cohort was significantly older (mean age of 53.6 ± 23.8 vs 45.6 ± 22.7 years). The mean RTS did not differ. P-HEMS assists increased to 116 (13.5 %). The number of CT scans, blood transfusion, and acute trauma surgical interventions decreased. Mean LOS, ICU admission, and ICU LOS did not differ. The mortality rate, however, decreased by 7.0 %, observed and predicted survival was significantly different in favour of the 2014 cohort, with a Z-score of 4.25. CONCLUSION: An increase in age is seen, though trauma scores remain comparable. The number of blood products transfused and acute trauma surgical interventions performed declines. Mortality significantly decreased and a significant difference in observed and predicted survival is seen. Showing improved trauma care in our hospital, in favour of the second period.

The influence of prehospital time on trauma patients outcome: a systematic review.

OBJECTIVE: Time is considered an essential determinant in the initial care of trauma patients. Salient tenet of trauma care is the 'golden hour', the immediate time after injury when resuscitation and stabilization are perceived to be most beneficial. Several prehospital strategies exist regarding time and transport of trauma patients. Literature shows little empirical knowledge on the exact influence of prehospital times on trauma patient outcome. The objective of this study was to systematically review the correlation between prehospital time intervals and the outcome of trauma patients. METHODS: A systematic review was performed in MEDLINE, Embase and the Cochrane Library from inception to May 19th, 2014. Studies reporting on prehospital time intervals for emergency medical services (EMS), outcome parameters and potential confounders for trauma patients were included. Two reviewers collected data and assessed the outcomes and risk of bias using the STROBE-tool. The primary outcome was the influence on mortality. RESULTS: Twenty level III-evidence articles were considered eligible for this systematic review. Results demonstrate a decrease in odds of mortality for the undifferentiated trauma patient when response-time or transfer-time are shorter. On the contrary increased on-scene time and total prehospital time are associated with increased odds of survival for this population. Nevertheless rapid transport does seem beneficial for patients suffering penetrating trauma, in particular hypotensive penetratingly injured patients and patients with a traumatic brain injury. CONCLUSION: Swift transport is beneficial for patients suffering neurotrauma and the haemodynamically unstable penetratingly injured patient. For haemodynamically stable undifferentiated trauma patients, increased on-scene-time and total prehospital time does not increase odds of mortality. For undifferentiated trauma patients, focus should be on the type of care delivered prehospital and not on rapid transport.

Reflective teaching of medical communication skills with DiViDU: assessing the level of student reflection on recorded consultations with simulated patients.

OBJECTIVE: Acquisition of effective, goal-oriented communication skills requires both practicing skills and reflective thinking. Reflection is a cyclic process of perceiving and analysing communication behaviour in terms of goals and effects and designing improved actions. Based on Korthagen's ALACT reflection model, communication training on history taking was designed. Objectives were to develop rating criteria for assessment of the students' level of reflection and to collect student evaluations of the reflective cycle components in the communication training. METHODS: All second year medical students recorded a consultation with a simulated patient. In DiViDU, a web-based ICT program, students reviewed the video, identified and marked three key events, attached written reflections and provided peer-feedback. Students' written reflections were rated on four reflection categories. A reflection-level score was based on a frequency count of the number of categories used over three reflections. Students filled out an evaluation questionnaire on components of the communication training. RESULTS: Data were analyzed of 304 (90.6%) students. The four reflection categories Observations, Motives, Effects and Goals of behaviour were used in 7-38%. Most students phrased undirected questions for improvement (93%). The average reflection score was 2.1 (S.D. 2.0). All training components were considered instructive. Acting was preferred most. Reviewing video was considered instructive. Self-reflection was considered more difficult than providing written feedback to the reflections of peers. CONCLUSION: Reflection on communication behaviour can be systematically implemented and measured in a structured way. Reflection levels were low, probably indicating a limited notion of goal-oriented attributes of communication skills. PRACTICE IMPLICATIONS: Early introduction of critical self-reflection facilitates acceptance of an important ability for physicians for continued life-long learning and becoming mindful practitioners.

Characterization of transmission of Pneumocystis carinii f. sp. muris through immunocompetent BALB/c mice.

By using mouse models, it has been shown that Pneumocystis carinii f. sp. muris can be transmitted to immunocompetent mice that are exposed to immunosuppressed mice with active P. carinii pneumonia. We sought to determine whether P. carinii f. sp. muris could be transmitted between normal mice. The rationale for these experiments was to demonstrate whether the normal host could serve as the reservoir of organisms that produce Pcp when the organism is acquired by the immunosuppressed host. Under the conditions of these experiments, normal mice are able to be infected by brief cohousing with P. carinii-infected SCID mice. There was active replication of organisms in the normal host such that the organism could be transmitted to other normal mice, again with active replication. Mice that had seroconverted after exposure to P. carinii-infected SCID mice were more resistant to infection when reexposed. Infection in normal mice was well tolerated with minimal effects on dynamic lung compliance. We speculate, based on these results, that transmission from normal host to normal host, as an asymptomatic or minimally symptomatic infection, could be a way to maintain this opportunistic pathogen in the environment.

[Susceptibility and immune responses to Pneumocystis carinii infection in different strains of mice by contagious transmission].

OBJECTIVE: To explore the susceptibility of different strains of mice to P. carinii infection and the host immune response to the organism. METHODS: C57BL/6 and BALB/c strains of mice (15 each) were exposed to SCID mice infected with P. carinii by co-housing. Observations were made on the number of parasites in the lungs, level of CD4+ T cell and CD8+ T cell in BALF, and serum IgG at 4, 5 and 6 wk after contagion. RESULTS: The number of P. carinii grew in the lungs of BALB/c mice was found much greater than those in C57BL/6 mice. A few number of P. carinii cysts were detected in the lungs of both strains of mice by 4 wk after co-housing, the number of cysts increased at 5 wk in the lungs of BALB/c mice but not in that of C57BL/6 mice. P. carinii-specific IgG in the sera and high level of CD62low CD4- and CD8-positive T cells in the lungs were found at 5 wk. The parasites were cleared from the lungs at 6 wk in all infected mice, shortly after acquired immune response was initiated. CONCLUSION: BALB/c mice are more susceptible to P. carinii than the C57BL/6 mice by natural transmission, and all the immunocompetent mice can clear the infection of P. carinii by cellular and humoral immune responses.

Cyclic ADP-ribose production by CD38 regulates intracellular calcium release, extracellular calcium influx and chemotaxis in neutrophils and is required for bacterial clearance in vivo.

Cyclic ADP-ribose is believed to be an important calcium-mobilizing second messenger in invertebrate, mammalian and plant cells. CD38, the best-characterized mammalian ADP-ribosyl cyclase, is postulated to be an important source of cyclic ADP-ribose in vivo. Using CD38-deficient mice, we demonstrate that the loss of CD38 renders mice susceptible to bacterial infections due to an inability of CD38-deficient neutrophils to directionally migrate to the site of infection. Furthermore, we show that cyclic ADP-ribose can directly induce intracellular Ca++ release in neutrophils and is required for sustained extracellular Ca++ influx in neutrophils that have been stimulated by the bacterial chemoattractant, formyl-methionyl-leucyl-phenylalanine (fMLP). Finally, we demonstrate that neutrophil chemotaxis to fMLP is dependent on Ca++ mobilization mediated by cyclic ADP-ribose. Thus, CD38 controls neutrophil chemotaxis to bacterial chemoattractants through its production of cyclic ADP-ribose, and acts as a critical regulator of inflammation and innate immune responses.

Antigen-specific CD8(+) T cells persist in the upper respiratory tract following influenza virus infection.

Because little is known about lymphocyte responses in the nasal mucosa, lymphocyte accumulation in the nasal mucosa, nasal-associated lymphoid tissue (NALT), and cervical lymph nodes (CLN) were determined after primary and heterosubtypic intranasal influenza challenge of mice. T cell accumulation peaked in the nasal mucosa on day 7, but peaked slightly earlier in the CLN (day 5) and later (day 10) in the NALT. Tetrameric staining of nasal mucosal cells revealed a peak accumulation of CD8 T cells specific for either the H-2D(b) influenza nucleoprotein epitope 366-374 (D(b)NP(366)) or the H-2D(b) polymerase 2 protein epitope 224-233 (D(b)PA(224)) at 7 days. By day 13, D(b)PA(224)-specific CD8 T cells were undetectable in the mucosa, whereas D(b)NP(366)-specific CD8 T cells persisted for at least 35 days in the mucosa and spleen. After heterosubtypic virus challenge, the accumulation of CD8 T cells in the nasal mucosa was quicker, more intense, and predominantly D(b)NP(366) specific relative to the primary inoculation. The kinetics and specificity of the CD8 T cell response were similar to those in the CLN, but the responses in the NALT and spleen were again slower and more protracted. These results indicate that similar to what was reported in the lung, D(b)NP(366)-specific CD8 T cells persist in the nasal mucosa after primary influenza infection and predominate in an intensified nasal mucosal response to heterosubtypic challenge. In addition, differences in the kinetics of the CD8 T cell responses in the CLN, NALT, and spleen suggest different roles of these lymphoid tissues in the mucosal response.

Pulmonary inflammation disrupts surfactant function during Pneumocystis carinii pneumonia.

During Pneumocystis carinii pneumonia (PCP) in mice, the degree of pulmonary inflammation correlates directly with the severity of lung function deficits. Therefore, studies were undertaken to determine whether the host inflammatory response contributes to PCP-related respiratory impairment, at least in part, by disrupting the pulmonary surfactant system. Protein and phospholipid content and surfactant activity were measured in the lavage fluid of infected mice in either the absence or presence of an inflammatory response. At 9 weeks postinfection with P. carinii, nonreconstituted SCID mice exhibited no signs of pulmonary inflammation, respiratory impairment, or surfactant dysfunction. Lavage fluid obtained from these mice had protein/phospholipid (Pr/PL) ratios (64% +/- 4.7%) and minimum surface tension values (4.0 +/- 0.9 mN/m) similar to those of P. carinii-free control mice. However, when infected SCID mice were immunologically reconstituted, an intense inflammatory response ensued. Pr/PL ratios (218% +/- 42%) and minimum surface tension values (27.2 +/- 2.7 mN/m) of the lavage fluid were significantly elevated compared to those of the lavage fluid from infected, nonreconstituted mice (P < 0.05). To examine the specific role of CD8(+) T-cell-mediated inflammation in surfactant dysfunction during PCP, mice with defined T-cell populations were studied. P. carinii-infected, CD4(+)-depleted mice had elevated lavage fluid Pr/PL ratios (126% +/- 20%) and elevated minimum surface tension values (16.3 +/- 1.0 mN/m) compared to normal mice (P < 0.05). However, when infected mice were additionally depleted of CD8(+) cells, Pr/PL ratios were normal and surfactant activity was improved. These findings demonstrate that the surfactant pathology associated with PCP is related to the inflammatory process rather than being a direct effect of P. carinii. Moreover, CD8(+) lymphocytes are involved in the mechanism leading to surfactant dysfunction.

Immunomodulatory effects of anti-CD4 antibody in host resistance against infections and tumors in human CD4 transgenic mice.

Anti-CD4 antibodies, which cause CD4(+) T-cell depletion, have been shown to increase susceptibility to infections in mice. Thus, development of anti-CD4 antibodies for clinical use raises potential concerns about suppression of host defense mechanisms against pathogens and tumors. The anti-human CD4 antibody keliximab, which binds only human and chimpanzee CD4, has been evaluated in host defense models using murine CD4 knockout-human CD4 transgenic (HuCD4/Tg) mice. In these mice, depletion of CD4(+) T cells by keliximab was associated with inhibition of anti-Pneumocystis carinii and anti-Candida albicans antibody responses and rendered HuCD4/Tg mice susceptible to P. carinii, a CD4-dependent pathogen, but did not compromise host defense against C. albicans infection. Treatment of HuCD4/Tg mice with corticosteroids impaired host immune responses and decreased survival for both infections. Resistance to experimental B16 melanoma metastases was not affected by treatment with keliximab, in contrast to an increase in tumor colonization caused by anti-T cell Thy1.2 and anti-asialo GM-1 antibodies. These data suggest an immunomodulatory rather than an overt immunosuppressive activity of keliximab. This was further demonstrated by the differential effect of keliximab on type 1 and type 2 cytokine expression in splenocytes stimulated ex vivo. Keliximab caused an initial up-regulation of interleukin-2 (IL-2) and gamma interferon, followed by transient down-regulation of IL-4 and IL-10. Taken together, the effects of keliximab in HuCD4/Tg mice suggest that in addition to depleting circulating CD4(+) T lymphocytes, keliximab has the capability of modulating the function of the remaining cells without causing general immunosuppression. Therefore, keliximab therapy may be beneficial in controlling certain autoimmune diseases.

Activated antigen-specific CD8+ T cells persist in the lungs following recovery from respiratory virus infections.

The poor correlation between cellular immunity to respiratory virus infections and the numbers of memory CD8(+) T cells in the secondary lymphoid organs suggests that there may be additional reservoirs of T cell memory to this class of infection. Here we identify a substantial population of Ag-specific T cells in the lung that persist for several months after recovery from an influenza or Sendai virus infection. These cells are present in high numbers in both the airways and lung parenchyma and can be distinguished from memory cell populations in the spleen and peripheral lymph nodes in terms of the relative frequencies among CD8(+) T cells, activation status, and kinetics of persistence. In addition, these cells are functional in terms of their ability to proliferate, express cytolytic activity, and secrete cytokines, although they do not express constitutive cytolytic activity. Adoptive transfer experiments demonstrated that the long-term establishment of activated T cells in the lung did not require infection in the lung by a pathogen carrying the inducing Ag. The kinetics of persistence of Ag-specific CD8(+) T cells in the lung suggests that they play a key role in protective cellular immunity to respiratory virus infections.

Production of interferon-gamma by influenza hemagglutinin-specific CD8 effector T cells influences the development of pulmonary immunopathology.

This study examined the inflammation, lung function impairment, and immune protection associated with either wild-type or interferon (IFN)-gamma-deficient Tc1- or Tc2-CD8 effector cells responding to influenza pneumonia. The adoptive transfer of influenza hemagglutinin-specific Tc1 effectors afforded protection and elicited only minimal impairment of lung function. IFN-gamma-deficient Tc1 effector cells were equally protective, but were associated with an eosinophil influx and slightly more lung function impairment early in the response. Relative to Tc1, Tc2 effector cells were less protective, elicited an eosinophil influx and a greater impairment of lung functions. IFN-gamma-deficient Tc2 effector cells were not protective and were associated with the severest impairment of lung function throughout the response, an accumulation of neutrophils, and extensive pulmonary vasculitis and alveolar hemorrhaging. Deletion of IFN-gamma was associated with a delay in effector cell recruitment and the elicitation of a more intense inflammatory response that resulted in more severe lung function impairment in the recipients of either Tc1 or Tc2 IFN-gamma-deficient effector cells. Thus, during influenza infections, IFN-gamma production by the responding CD8 T cells is associated with effector cell recruitment and mitigation of the associated inflammation and of the resulting impairment in lung functions but is not necessary for optimal protection.

Pneumocystis carinii enhances soluble mannose receptor production by macrophages.

Phagocytosis of extracellular organisms in the alveolar spaces of the lungs represents the first-line of host defense against pulmonary pathogens. Disruption of this process is likely to interfere with the generation of appropriate specific immune responses, and lead to a delayed or inefficient clearance of the pathogen. Pneumocystis carinii, an opportunistic pathogen in immunodeficient individuals, is cleared from the lung by alveolar macrophages. In the absence of specific anti-Pneumocystis antibodies, phagocytosis is dependent on the non-opsonic macrophage mannose receptor (MR). Recent studies have demonstrated that alveolar macrophage MR activity is downregulated in individuals infected with HIV, and that functional MR is shed from the macrophage cell surface. Here we report that P. carinii enhances the formation of soluble MR by macrophages in vitro. Soluble MR was detected in cell-free alveolar fluid from humans infected with HIV and/or P. carinii, but not in alveolar fluid from healthy controls. Soluble MR was found in association with extracellular clumps of P. carinii in the lungs of mice with P. carinii pneumonia, and was associated with P. carinii organisms purified from these mice. When purified P. carinii organisms were incubated with soluble MR-containing supernatants, they were phagocytosed less readily by alveolar macrophages than were control organisms. Our results suggest that P. carinii organisms enhance the shedding of MR from the surface of alveolar macrophages, and that the resultant soluble MR binds to intra-alveolar organisms, thereby interfering with their non-opsonic uptake via the macrophage cell surface MR.

A soluble mannose receptor immunoadhesin enhances phagocytosis of Pneumocystis carinii by human polymorphonuclear leukocytes in vitro.

Pneumocystis carinii is an opportunistic pathogen that causes pneumonia in immunocompromised hosts. In the normal host, P. carinii is susceptible to an array of first line host defense mechanisms that are operative in the lung. Alveolar macrophages play a central role in the clearance of inhaled organisms. The macrophage mannose receptor (MR) appears to be sufficient for P. carinii phagocytosis. In individuals infected with the human immunodeficiency virus, MR expression on alveolar macrophages and P. carinii phagocytosis are decreased, however, Fc-receptor mediated phagocytosis remains intact. In this study, we demonstrate that a recombinant soluble MR immunoadhesin, consisting of the essential carbohydrate binding MR ectodomain and the Fc-region of human immunoglobulin (Ig)G1, binds P. carinii and leads to an 8.2-fold increased uptake of P. carinii by phagocytic cells. Our results suggest that the soluble MR immunoadhesin may have therapeutic potential in the treatment of P. carinii infections.

Preclinical development of keliximab, a Primatized anti-CD4 monoclonal antibody, in human CD4 transgenic mice: characterization of the model and safety studies.

The preclinical safety assessment of biopharmaceuticals necessitates that studies be conducted in species in which the products are pharmacologically active. Monoclonal antibodies are a promising class of biopharmaceuticals for many disease indications; however, by design, these agents tend to have limited species cross-reactivity and tend to only be active in primates. Keliximab is a human-cynomolgus monkey chimeric (Primatized) monoclonal antibody with specificity for human and chimpanzee CD4. In order to conduct a comprehensive preclinical safety assessment of this antibody to support chronic treatment of rheumatoid arthritis in patients, a human CD4 transgenic mouse was used for chronic and reproductive toxicity studies and for genotoxic studies. In addition, immunotoxicity studies were conducted in these mice with Candida albicans, Pneumocystis carinii and B16 melanoma cells to assess the effects of keliximab on host resistance to infection and immunosurveillance to neoplasia. The results of these studies found keliximab to be well tolerated with the only effects observed being related to its pharmacologic activity on CD4+ T lymphocytes. The use of transgenic mice expressing human proteins provides a useful alternative to studies in chimpanzees with biopharmaceutical agents having limited species cross-reactivity.

The role of CD8+ T cells in the pathogenesis of Pneumocystis carinii pneumonia in mice depleted of CD4+ T cells.

OBJECTIVE: To define the cell populations contributing to inflammation-associated respiratory impairment in Pneumocystis carinii pneumonia (PCP). METHODS: The host inflammation response was observed in CD4+ T cell-depleted mice and in CD4+ and CD8+ T cell-depleted mice infected with P. carinii via intratracheal inoculation. RESULTS: Mice depleted of both CD4+ and CD8+ T cells developed infection with neither increased respiratory rate nor lung injury. In contrast, mice depleted of CD4+ T cells alone exhibited severe pulmonary inflammation, and increased respiratory rates. Respiratory compromise was associated with the presence of activated CD8+ cells and neutrophils in the BALF. CONCLUSION: The host's inflammatory cell response to P. carinii directly impairs pulmonary function and contributes to the pathogenesis of PCP, CD8+ T cells appear to play a major role.

Immune-mediated inflammation directly impairs pulmonary function, contributing to the pathogenesis of Pneumocystis carinii pneumonia.

The clinical severity of Pneumocystis carinii pneumonia (PCP) correlates closely with the appearance of pulmonary markers of inflammation. Therefore, a model system was developed whereby physiological studies could be performed on live mice to determine the extent to which pulmonary inflammation contributes to respiratory impairment during PCP. P. carinii-infected severe combined immunodeficient mice displayed little evidence of pulmonary inflammation and exhibited normal oxygenation and dynamic lung compliance. When comparably infected littermates were immunologically reconstituted, however, an intense immune-mediated inflammatory response was observed that resulted in significant decreases in both lung compliance and oxygenation. As the pneumonia resolved pulmonary function returned toward normal. To begin to define the cell populations contributing to inflammation-associated respiratory impairment during PCP, similar studies were performed in CD4(+) T cell-depleted mice. Mice depleted of both CD4(+) and CD8(+) cells developed infection, but they demonstrated neither abnormal lung compliance nor increased respiratory rate and displayed no markers of lung injury. In contrast, mice depleted of only CD4(+) T cells exhibited severe pulmonary inflammation and injury, decreased oxygenation and lung compliance, and increased respirations. Respiratory compromise was associated with the presence of activated CD8(+) cells and neutrophils in broncho-alveolar lavage fluid. These observations provide direct experimental evidence that the host's response to P. carinii directly impairs pulmonary function and contributes to the pathogenesis of PCP. Furthermore, CD8(+) T cells likely contribute to the respiratory compromise observed during PCP.

Chemokine gene expression during Pneumocystis carinii-driven pulmonary inflammation.

Severe combined immunodeficient (SCID) mice lack functional lymphocytes and therefore develop Pneumocystis carinii pneumonia. However, when infected SCID mice are immunologically reconstituted with congenic spleen cells, a protective inflammatory cascade is initiated. Proinflammatory cytokines are produced, and lymphocytes and macrophages are recruited specifically to alveolar sites of infection. Importantly, uninfected regions of the lung remain free from inflammatory involvement, suggesting that there are specific mechanisms that limit inflammation in the infected lung. Therefore, to determine whether chemokines are involved in targeting the P. carinii-driven inflammatory response, steady-state mRNA levels of several chemokines were measured in the lungs of both reconstituted and nonreconstituted P. carinii-infected SCID mice. Despite significant organism burdens in the lungs of 8- and 10-week-old SCID mice, there was no evidence of elevated chemokine gene expression, which is consistent with the lack of an inflammatory response in these animals. However, when 8-week-old infected SCID mice were immunologically reconstituted, signs of focal pulmonary inflammation were observed, and levels of RANTES, MCP-1, lymphotactin, MIP-1alpha, MIP-1beta, and MIP-2 mRNAs were all significantly elevated. Chemokine mRNA abundance was elevated at day 10 postreconstitution (PR), was maximal at day 12 PR, and returned to baseline by day 22 PR. In situ hybridization demonstrated that during the peak of inflammation, RANTES gene expression was localized to sites of inflammatory cell infiltration and P. carinii infection. Thus, these observations indicate that chemokines play a role in the focal targeting of inflammatory cell recruitment to sites of P. carinii infection after the passive transfer of lymphocytes to the host.

Bone marrow-derived cells are required for the induction of a pulmonary inflammatory response mediated by CD40 ligation.

The expression of inflammatory mediators by various cells following in vitro CD40 ligation is well known. However, knowledge of the role and interaction with these cells in the establishment and maintenance of in vivo immune-mediated inflammation is limited. In this report, a chimeric mouse model based on CD40 knockout and wild-type mice was used to assess the role of bone marrow (BM)-derived and non-BM-derived cells in a CD40-mediated pulmonary inflammation response. CD40+ BM-derived cells were required for initial cell recruitment, pulmonary edema, and weight loss associated with this response. The structural CD40+ non-BM-derived cells of the lung, such as fibroblasts, epithelial cells, and endothelial cells, could not by themselves establish any level of pulmonary inflammation. However, both the CD40+ BM-derived cells and the structural CD40+ non-BM-derived cells of the lung were required to maximize the level of pulmonary inflammation. Both B cells and T cells played a contributing role in macrophage recruitment and pulmonary edema but neither contributed to the inflammation-associated weight loss. These experiments indicate that CD40+ BM-derived cells were critical to the induction of pulmonary inflammation and that alveolar macrophages, B cells, and T cells contributed to selective aspects of the response.

Migration kinetics and final destination of type 1 and type 2 CD8 effector cells predict protection against pulmonary virus infection.

The requirements for CD8 T cells to provide protection against a localized virus infection in models of adoptive immunotherapy are not well defined. Here we investigated the protective value of defined in vitro-generated hemagglutinin (HA) peptide-specific primary CD8 T cell effectors from the clone 4 T cell receptor transgenic mice, secreting type 1 or type 2 cytokines, against pulmonary infection with whole influenza virus. Cytotoxic T lymphocytes producing type 1 and type 2 cytokine (Tc1 and Tc2) populations were equally cytolytic, but Tc1 effectors and not Tc2 effectors reduced the pulmonary virus titer early during infection. Host recovery mediated by Tc1 effectors was found to be independent of interferon gamma production. Tc2 effectors entered the lung with delayed kinetics as compared with Tc1 effectors, and after lung entry Tc2 effector cells did not localize near the infected airway epithelium as did Tc1 effectors but were found within clusters of inflammatory cells distant from the epithelium. We also show that the expression of several chemokine receptors was selectively regulated in the Tc1 and Tc2 subsets. Thus, the protective value of a CD8 cell population against pulmonary influenza virus infection is strongly correlated with its ability to exert its effector potential at the site of virus infection.