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Primary infection with the gastrointestinal nematode Heligmosomoides polygyrus bakeri is chronic in C57BL/6 (B6) mice whereas challenge infection is rapidly eliminated. F4/80

Complex cytokine interactions occur during blood-stage malaria which offer a unique opportunity to study their influence on the pathogenesis of malarial anaemia. Plasmodium chabaudi AS susceptible A/J mice experience severe and fatal anaemia whereas resistant C57BL/6 (B6) mice survive following moderate anaemia. In this study we analysed the role of IL-12 in erythropoiesis and tested whether the levels of IL-12 produced in these mice correlated with the extent of anaemia. In vitro, IL-12 significantly enhanced the numbers of erythroid burst (BFU-E) and colony forming units (CFU-E) in bone marrow and spleen cells from normal and day 7 infected A/J and B6 mice. Despite the presence of IL-12 in vitro, the level of splenic erythropoiesis in infected A/J mice was significantly lower than in B6 mice. Moreover, sera from infected B6 mice, but not A/J mice, significantly up-regulated erythropoiesis in vitro and this enhancement correlated with several fold higher levels of IL-12 in the sera of B6 compared to A/J mice. Furthermore, the erythropoietic potentiating effect of sera from infected B6 mice was abrogated following depletion of IL-12. Taken together, these findings suggest that defective IL-12 production in A/J mice during the early course of infection may result in fatal anaemia.

Our recent study showed that IL-12 treatment of susceptible A/J mice induces Th1-mediated, protective immunity against lethal blood-stage Plasmodium chabaudi AS infection. To further understand the mechanism of this protection, we examined NK cell cytotoxic (NKCC) and cytokine secretory functions in untreated and IL-12-treated A/J mice, along with resistant C57BL/6 (B6) mice. Normal A/J mice receiving six daily doses of 0.1 microg IL-12 exhibited significant increases in NKCC in total spleen cell populations. Defective NKCC evident in vitro in enriched NK cells from infected A/J mice was corrected by addition of 10 ng/ml IL-12 and was comparable with that seen in B6 mice. In vivo and in vitro analyses revealed that enriched NK cells from day 6 infected A/J mice were defective not only in NKCC, but also in IFN-gamma, and to a certain extent, TNF-alpha secretion, which could also be corrected by IL-12 treatment. Depletion of NK cells from resistant B6 mice resulted in a more severe course of infection, while NK cell-depleted, IL-12-treated A/J mice had significantly higher parasitemia, as well as 100% mortality, suggesting the importance of NK cells in IL-12-mediated protection. NKCC-defective bg/bg mice produced optimum IFN-gamma and TNF-alpha and recovered from infection similar to bg/+ controls; in vivo depletion of these cytokines resulted in significantly higher parasitemia early in infection. Based on these results, we conclude that IFN-gamma, and possibly TNF-alpha, secretion by NK cells during early infection plays a major role in protective immunity to blood-stage malaria.

The effects of IL-12 administration on the development of protective immunity to blood-stage Plasmodium chabaudi AS were analyzed. Treatment of susceptible A/J mice on the day of infection and for 5 days postinfection with various doses 0.025-0.3 microgram) of rIL-12 significantly decreased the peak parasitemia level, but only treatment with 0.1 microgram resulted in increased survival. Treatment of resistant B6 mice with 0.1 microgram of rIL-12 using the same regimen also significantly decreased the peak parasitemia level, but 40% of the animals died. Treatment of these mice with anti-IL-12 mAb resulted in a more severe course of infection, but survival was not significantly altered. The mechanism of IL-12-induced resistance was examined in A/J mice during infection. Compared with spleen cells from untreated mice, cells from IL-12-treated mice produced significantly higher levels of IFN-gamma spontaneously as well as in response to Con A or Ag stimulation on day 7 postinfection. Significantly higher levels of INF-gamma and TNF-alpha were found in the sera of IL-12-treated mice, which correlated with high levels of the nitric oxide (NO) metabolite, NO3-. Furthermore, CD4+T cell depletion was found to abrogate IL-12-induced resistance. Administration of neutralizing mAb against IFN-gamma or TNF-alpha to IL-12-treated mice showed that simultaneous depletion of both cytokines resulted in 100% mortality. The role of NO was investigated by administration of aminoguanidine, a selective inhibitor of cytokine-inducible nitric oxide synthase, to IL-12-treated mice. Significantly increased mortality was observed following treatment twice daily with 9 mg of aminoguanidine, but there was no effect on parasitemia. In conclusion, these results demonstrate that IL-12 regulates the development of resistance to P. chabaudi AS via a CD4+ Th1 response, which involves the cytokines IFN-gamma and TNF-alpha, and is in part NO dependent. Therefore, IL-12, given in the appropriate dose, may be useful in the induction of protective immunity to blood-state malaria.

To investigate the effect of caspase-12 deficiency on IFN-γ- independent control of blood-stage malaria, we compared lethal Plasmodium yoelii 17XL infection in wild-type C57BL ⁄ 6J and caspase-12-/-mice. Infected caspase-12-/- mice exhibited higher parasitaemia than WT mice on days 8 and 9 post-inoculation, but all WT and caspase-12-/- mice succumbed by day 10. In addition, infected caspase-12-/-mice had significantly elevated levels of IFN-γ, TNF, IL-18,and IL-10 in sera compared to infected WT mice. At the terminal stage of disease, there were no differences in cytokine levels in the tissues of infected WT and caspase-12-/- mice. However, liver pathology was more severe in infected caspase-12-/- mice compared to infected WT mice. Together, these findings indicate that although caspase-12 deficiency results in enhanced pro-inflammatory and immunoregulatory cytokine levels in sera during P. yoelii 17XL infection, these responses are not essential for protection against lethal malaria infection.

The discovery of the CFTR gene in 1989 has lead to rapid progress in understanding the molecular basis of cystic fibrosis (CF) and the biological properties of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. However, more than 10 years later, recurrent lung infections with Pseudomonas aeruginosa, which lead to chronic lung disease and eventual respiratory failure, remain the major cause of morbidity and mortality among CF patients. A distinguishing feature of lung disease in CF is an exaggerated and persistent inflammatory response, characterized by the accumulation of excessive numbers of neutrophils and dysregulated cytokine production. The events leading to the establishment of lung infection with P. aeruginosa, especially the inflammatory and immunological events, and the relation between the CF defect and infection, remain largely undefined. Progress in this area has been hampered by the lack of a suitable animal model. An exciting achievement in the past few years has been the development of a number of variants of CFTR-deficient mice which exhibit defective cAMP-mediated Cl(-) conductance and have a range of clinical phenotypes from mild to severe. In parallel, a model of chronic P. aeruginosa lung infection has been established in genetically and immunologically well-defined inbred mouse strains which differ in susceptibility to this infection in the lung. BALB/c mice are resistant, while DBA/2 mice are extremely susceptible, with high mortality within 3 days of infection. C57BL/6 and A/J mice are relatively susceptible and experience low mortality. Furthermore, the bacterial load correlates with the magnitude and quality of the inflammatory response in the infected lungs of BALB/c and C57BL/6 mice. Although results of infection studies in CFTR-deficient mice have been variable, C57BL/6-Cftr(m1UNC)/Cftr(m1UNC) knockout mice compared to littermate control mice are highly susceptible to chronic P. aeruginosa infection in the lung. The availability of CFTR knockout mice and non-CF inbred mice differing in susceptibility to chronic P. aeruginosa infection offers useful tools for progress in understanding the genesis of chronic P. aeruginosa infection and the ensuing inflammation in the CF lung, as well as the relation between the CF defect and infection. Information generated from these studies will provide the rationale for the development of novel immunomodulatory measures capable of ameliorating or modulating the chronic inflammation associated with CF lung disease.

Chronic bronchopulmonary Pseudomonas aeruginosa infection, initiated by intratracheal instillation of 1 to 2 x 10(5) colony-forming units of a mucoid strain of bacteria trapped in agar beads, was characterized in resistant BALB/c mice and susceptible C57BL/6 (B6) mice through 28 d postinfection. B6 mice experienced a more severe infection than BALB/c mice as evidenced by significantly higher mortality and significantly greater weight loss during the first 14 d. Furthermore, B6 mice had significantly higher numbers of bacteria in the lungs through 21 d after infection. Overall, only 22% of these hosts cleared the infection. In contrast, 67% of BALB/c mice cleared the infection. These differences between resistant and susceptible mice were found to correlate with histopathologic differences in the type of inflammation and the extent of tissue damage. An acute, predominantly neutrophilic inflammation and extensive tissue damage were apparent in the lungs of susceptible B6 mice, whereas chronic, granulomatous inflammation and little or no tissue damage were visible in resistant BALB/c mice. The finding of acute inflammation in the lungs of infected B6 mice was confirmed by fluorescence-activated cell sorter (FACS) analyses, which demonstrated that these mice had significantly greater proportions of polymorphonuclear neutrophils in the lungs on Days 7 and 14 after infection than did BALB/c mice. FACS analyses also revealed significant and similar increases in CD3(+) lung cells in both strains as the infection progressed. The CD4/CD8 ratio was significantly greater in BALB/c mice by 21 d after infection when the majority of these animals, but not B6 mice, had cleared the infection.

As previously reported, blood-stage Plasmodium chabaudi AS malaria is lethal by days 10-12 postinfection in susceptible A/J mice that mount an early, predominantly Th2 response. In contrast, resistant C57BL/6 (B6) mice clear the infection by 4 wk with an early Th1 response. In this study, we analyzed in vivo production of IL-12, a potent Th1-inducing cytokine, during the first 5 days after P. chabaudi AS infection in these mice. By day 2, serum IL-12 p70 levels were significantly increased in B6 mice over basal levels and were also significantly higher compared with A/J mice that showed no significant changes in serum p70 levels after infection. Splenectomy of resistant B6 mice before infection demonstrated that the spleen is the major source of systemic IL-12 in these hosts. Splenic mRNA levels of both p40 and p35 were significantly higher in A/J mice; however, the ratios of p40/p35 mRNA levels were similarly up-regulated in both strains. Furthermore, B6 but not A/J mice showed significant up-regulation of splenic IL-12R beta2 mRNA over basal levels by days 3 and 4, coincident with sustained up-regulation of splenic IFN-gamma mRNA levels on days 3-5. However, IL-12R beta1 mRNA levels in the spleen were similarly up-regulated in both mouse strains by day 3. Taken together, these data suggest that high systemic IL-12 production, accompanied by an early and sustained up-regulation of both IL-12R beta1 and beta2 mRNA levels in the spleen, as occurs in resistant B6 mice, appears to preferentially induce protective Th1 responses against blood-stage malaria.

Complex cytokine interactions occur during blood-stage malaria which offer a unique opportunity to study their influence on the pathogenesis of malarial anaemia. Plasmodium chabaudi AS susceptible A/J mice experience severe and fatal anaemia whereas resistant C57BL/6 (B6) mice survive following moderate anaemia. In this study we analysed the role of IL-12 in erythropoiesis and tested whether the levels of IL-12 produced in these mice correlated with the extent of anaemia. In vitro, IL-12 significantly enhanced the numbers of erythroid burst (BFU-E) and colony forming units (CFU-E) in bone marrow and spleen cells from normal and day 7 infected A/J and B6 mice. Despite the presence of IL-12 in vitro, the level of splenic erythropoiesis in infected A/J mice was significantly lower than in B6 mice. Moreover, sera from infected B6 mice, but not A/J mice, significantly up-regulated erythropoiesis in vitro and this enhancement correlated with several fold higher levels of IL-12 in the sera of B6 compared to A/J mice. Furthermore, the erythropoietic potentiating effect of sera from infected B6 mice was abrogated following depletion of IL-12. Taken together, these findings suggest that defective IL-12 production in A/J mice during the early course of infection may result in fatal anaemia.

The in vivo role of interleukin (IL)-12 in correcting anemia and the underlying defect in erythropoiesis in Plasmodium chabaudi AS-susceptible A/J mice was examined. Six daily intraperitoneal injections of 0.1 microg IL-12 in A/J mice, beginning on the day of infection, rapidly and significantly enhanced bone marrow and splenic erythropoiesis as demonstrated by marked increases in early and late committed erythroid progenitors, the erythroid burst (BFU-E) and colony-forming units (CFU-E), respectively, compared with control mice. The most dramatic effect of IL-12 treatment was a sevenfold increase in the number of splenic CFU-E on day 7 postinfection, compared with untreated, infected A/J mice. Treatment with IL-12 also caused significant increases in hematocrit levels, erythrocyte counts, percentage of reticulocytes, spleen cellularity, and frequencies of BFU-E and CFU-E in the bone marrow and spleen of A/J mice during infection. The frequency of BFU-E in the peripheral blood of these mice was also significantly increased, suggesting enhanced mobilization of precursor cells to the spleen as well as increased production of erythroid precursors in this organ. Consistent with previous observations using higher doses, 0.1 microg IL-12 administered daily for 6 days to normal A/J mice significantly decreased bone marrow erythropoiesis and significantly increased splenic erythropoiesis. However, the influence of IL-12 on erythropoiesis was much more pronounced during ongoing malaria infection. These results suggest a role for IL-12 during blood-stage malaria in not only enhancing the development of protective immunity but also in alleviating malaria-induced anemia by increasing the number of erythroid precursors and enhancing the expansion of committed erythroid progenitors.

The production and function of nitric oxide during the early phase of blood-stage infection with Plasmodium chabaudi AS was analyzed using two inbred strains of mice that differ in the level of resistance to this parasite. Northern blot analysis of in vivo expression of inducible nitric oxide synthase (iNOS) revealed that early during infection resistant C57BL/6 mice, which clear the infection by 4 wk, have higher levels of iNOS mRNA in the spleen than susceptible A/J mice. In contrast, susceptible A/J mice have significantly increased levels of iNOS mRNA in the liver later in the course of infection just before death occurs. Splenic macrophages recovered from resistant C57BL/6 mice on day 7 postinfection express iNOS mRNA which is up-regulated following overnight stimulation of the cells with LPS. Furthermore, during the first week postinfection, splenic macrophages recovered from resistant hosts produce significantly higher levels of nitrite (NO2-) in vitro in response to LPS than similarly stimulated macrophages from susceptible A/J mice. Increased levels of nitrate (NO3-) were only detected in serum of resistant C57BL/6 mice at the time of peak parasitemia. Treatment with the iNOS inhibitor, aminoguanidine, reduced NO3- levels in serum of C57BL/6 mice and eliminated resistance of these hosts to P. chabaudi AS malaria without affecting parasitemia. These results demonstrate that the ability to produce high amounts of nitric oxide (NO) early during infection with blood-stage P. chabaudi AS correlates with resistance, but that NO may not be involved in parasite killing. Moreover, the tissue site of NO production, that is, spleen vs liver, appears to be critical and correlates with resistance vs susceptibility to P. chabaudi AS malaria, respectively.

Pelvic infection is the commonest complication of legal abortion. The presence of lower genital tract infections increases the risk of complications, and women requesting abortion are at significant risk of harbouring sexually transmitted diseases (STD). Prophylactic antibiotic treatment can decrease the rate of post-abortal sepsis, but the optimum regime is unclear. In particular, patients with Chlamydia trachomatis infection, and bacterial vaginosis would appear to be at increased risk, and detection and treatment of these conditions can lower this risk. The opportunity to screen and treat for STD presents itself in this setting, allowing patients and their sexual contacts to benefit, with a decrease in the infected pool in the community.Induced abortion is one of the most frequent surgical procedures in the UK. Even though it is considered safe, it sometimes has complications and long-term sequelae. Pelvic inflammatory disease (PID) is the most prevalent complication and can lead to chronic pelvic pain, pain during intercourse, infertility, and a higher risk of ectopic pregnancy. Chlamydia trachomatis is perhaps the leading etiologic agent for PID among women who have undergone induced abortion and who develop PID. Gonorrhea is another major etiologic agent for PID. Strategies used to try to reduce pelvic infection revolve around administration of antibiotic prophylaxis based on demographic features and on the presence of certain organisms in the genital tract that may increase their risk (e.g., C. trachomatis and Neisseria gonorrhoeae) and universal antibiotic prophylaxis for all women undergoing abortion. Most of the literature suggests that antibiotic prophylaxis does provide some protection against PID but does not clearly indicate who should be screened and for which pathogens and who should be treated and with which antibiotics. Demographic features useful for identifying who should receive antibiotic prophylaxis are: a history of PID, single status, nulliparity, and youth (especially reliable for chlamydial infection). Screening for bacterial vaginosis involves diagnosis based on 3 of 4 criteria: characteristic vaginal discharge, positive amine test, raised vaginal pH, and the presence of clue cells on microscopy of wet or stained preparations of vaginal discharge. Since C. trachomatis is the most important pathogen, drugs sensitive to it should be administered: tetracyclines and erythromycin. Screening women seeking abortion for sexually transmitted diseases (STDs) provides an opportunity to educate them about STDs and treatment compliance and to contact their partners for investigation, treatment, and contact-tracing to reduce the STD-infected pool in the community.

Over 11 million units of red blood cells are transfused each year in the United States at a cost of over $2 billion. This paper reviews the indications for and the risks of red blood cell transfusions, and provides guidelines for transfusions in both surgical and non-surgical settings.

The importance of severe anemia in the mortality of susceptible A/J mice during blood-stage Plasmodium chabaudi AS infection was assessed. Blood transfusion during and 2 to 3 days after peak parasitemia rescued 90% of susceptible mice from severe anemia and death and allowed these mice to clear the infection and acquire immunity to reinfection. However, blood transfusion prolonged the patency of the infection for up to 5 days after peak parasitemia. Blood transfusions in resistant C57BL/6 mice produced an identical effect, that is, prolongation of the patency of parasitemia. In addition, blood transfusion increased the numbers of gametocytes in both mouse strains. In both strains of mice, the rapid reduction in parasitemia, which occurs during crisis, was associated with the development of moderate levels of anemia. The possible mechanisms for the modulation of parasitemia by blood transfusion and the implications of the present observations for our understanding of the events which occur during crisis are discussed. It is proposed that parasitologic crisis is induced and/or maintained by physiological alterations associated with anemia.

Malaria, which is caused by hemoprotozoan parasites of the genus Plasmodium, has once again reached epidemic proportions. The resurgence of malaria has occurred because the parasite has developed resistance to the anti-malarial drugs and the mosquito vector has developed resistance to the insecticides. Added to these impediments is the problem that, in spite of intense efforts by researchers world-wide, there is yet no effective anti-malarial vaccine. Our lack of knowledge concerning the exact mechanism of the host immune response to infection with Plasmodium parasites has contributed significantly to the lack of an effective and safe vaccine. The role of an antibody-independent, cell-mediated mechanism which can result in the generation of soluble mediators or cytokines by T lymphocytes and macrophages in host defense against blood stage malaria is being actively investigated in humans and in mice with malaria. With the availability of recombinant lymphokines and monokines and neutralizing antibodies against these reagents it is now possible to determine the role of cytokines in the development of protective anti-malarial immunity. In this review, we discuss recent evidence from human studies and experimental murine models concerning the possible roles of cytokines in malaria.

The mobilization of adequate numbers of mononuclear phagocytes to inflammatory foci was measured in Listeria-resistant and Listeria-sensitive mice. Resistant strains, such as B10.A, were found to have a 2- to 3-fold greater accumulation of peritoneal macrophages after i.p. treatment with a variety of nonspecific inflammatory stimuli in comparison to sensitive strains, such s A/J. In addition to low macrophage inflammatory responses, A/J mice had fewer resident peritoneal macrophages. Moreover, measurement of chemotaxis in vitro of equal numbers of thioglycollate-induced macrophages showed cells from A/J mice to be less responsive to complement-derived chemotactic factors. Thus, the mononuclear phagocyte systems of resistant B10.A and sensitive A/J mice were quantitatively and qualitatively different. A survey of inbred mouse strains revealed that these differences were not peculiar to A strain mice and that, in general, the level of the in vivo macrophage inflammatory response correlated with the level of resistance to Listeria in a given strain. Like resistance to Listeria, the macrophage inflammatory response was found to be genetically controlled by an autosomal, non-H-2-linked gene(s) expressed as incompletely dominant. Backcross analysis showed genetic linkage of the macrophage inflammatory response with resistance to Listeria. Thus, the results of this study provide formal evidence that the cellular basis of the genetically determined, enhanced resistance to Listeria is an augmented pool size of mononuclear phagocytes, and the prompt mobilization of these cells to foci of infection.

Susceptibility to lethal effects of Rickettsia akari varies among mouse strains. Although most strains are resistant, A/J mice are extremely sensitive (10,000-fold difference in LD50 between resistant and sensitive strains). In contrast to most strains of mice, A/J mice also fail to develop activated, tumoricidal macrophages after any of several in vivo or in vitro treatments. Are susceptibility to R. akari and inability to develop activated, cytotoxic macrophages in the A/J strain causally related traits? Genetic analysis of macrophage tumoricidal activity in responsive B10.A and nonresponsive A mice suggested this trait was controlled by a single, autosomal, dominant gene. Among (F1 X A) backcross mice, the traits for defective macrophage cytotoxicity and abnormal accumulation of macrophages during inflammation (a response controlled by a single, autosomal, dominant gene) segregated independently. Genetic analysis of resistance to R. akari in sensitive A and resistant B10.A mice suggested this trait was also controlled by a single, autosomal, dominant gene. Among (F1 X A) backcross mice, however, traits for defective macrophage cytotoxicity and R. akari resistance segregated independently. Thus, development of activated tumoricidal macrophages, accumulation of macrophages at sites of inflammation, and resistance to the lethal effects of R. akari in A and B10.A mice were each controlled by single, autosomal, dominant, non-H-2-linked genes. However, genes for control of macrophage activation for tumoricidal activity and for resistance to lethal effects of R. akari infection are distinct.

SummaryADP-induced platelet aggregation and the breakdown of ADP in platelet-poor plasma of normal and magnesium deficient calves and rats have been studied. There was no statistically significant difference in ADP-induced platelet aggregation between the treated and untreated groups of animals. There was a significant difference in the ADP breakdown in platelet poor plasma of magnesium deficient rats as compared to the untreated animals. The platelet count of the magnesium deficient calves and in the citrated platelet-rich plasma of the magnesium deficient rats was not different from the normal. The thrombin clotting and partial thromboplastin times were significantly shortened in the magnesium deficient calves, but the prothrombin time was not affected. These findings suggest that pathological alterations in the serum magnesium levels that are still compatible with life do not influence adenosine diphosphate-induced platelet aggregation but do affect the breakdown of adenosine diphosphate in the plasma of rats. Just as magnesium administration may produce an anticoagulant effect, so may magnesium depletion produce a procoagulant effect in the blood of animals rendered magnesium deficient by diet. The clinical implications of this are discussed.

The in vivo primary antibody response to sheep erythrocytes (SRBC) was determined in genetically resistant C57BL/6 and susceptible A/J mice during the course of infection with Plasmodium chabaudi. Spleen cells from both strains of mice, immunized with SRBC and infected on the same day, showed significant increases in the number of direct plaque-forming cells. The response of malaria-infected C57BL/6 mice was significantly enhanced in comparison with the responses of both normal C57BL/6 and malaria-infected A/J mice. When mice were immunized at later times in the infection, the level of the response declined in both strains until it was less than 50% of the response of normal mice. Thus, suppression of the primary antibody response to SRBC does not correlate with the outcome of P. chaubaudi infection in genetically resistant and susceptible hosts.

Selective deficiency of serum IgA is the most common immunodeficiency in humans; when immunodeficient individuals receive blood transfusions a severe anaphylactoid reaction can develop. The present report describes such a patient. After the transfusion reaction a hemagglutination inhibition assay revealed that her blood contained less than 1.0 micrograms/ml of IgA and an anti-IgA antibody that reacted with the 2 IgA proteins, isotypes IgA1 and IgA2. Immediately after the reaction the patient's serum anti-IgA antibody titer was 1:16,384, and when reevaluated 5 weeks later it was 1:8000. All 3 of her children were shown to be IgA deficient, and 2 of them had antibodies against IgA2. This type of anaphylactoid reaction can be avoided by transfusing blood from IgA-deficient donors, frozen deglycerolized red cells, or red cells that have been washed several times to extract all IgA proteins.

Significant interstrain variations in the expression of numerous elements of the macrophage response to infection, which are commonly observed among inbred mice living in a controlled environment suggest that such traits are genetically controlled. The recent increase in awareness of these inherited variations can be attributed to the expectation that the analysis of such experiments of nature, namely, of the mouse strains with well-defined in vitro ‘macrophage’ defects, may enhance our understanding of the mechanisms underlying certain specific steps of macrophage response as well as of their correlation with in vivo host defense function.

In a previous pilot study that did not reach statistical significance, intermittent single-leg pneumatic compression appeared effective in reducing the incidence of calf vein thrombosis not only in the pumped calf but also in the unpumped leg in 37 patients, using the 125I-fibrinogen (Abbott Laboratories) technique. The present study was undertaken to investigate mechanical induction of local and systemic fibrinolysis. The euglobulin lysis time in the arm venous effluent was determined in five volunteers before and after unilateral arm compression for 1/2 hour. Shortening averaged 19% (not significant). The experiment was repeated using bilateral calf-length boots with femoral vein sampling. Euglobulin lysis decreased 22% (P0.001). To uncover possible systemic effects, the protocol was altered using calf boots with sampling from the arm. The euglobulin lysis diminished 6% in 57 volunteers (P0.001). In 27 others the effects of thigh-length and calf-length boots were compared. In half, pumping with a short boot was undertaken first, and in the remainder, the long boot was applied initially. One-half hour of pumping was followed by 1/2 hour of rest. Immediately afterward the second period of pumping took place and continued for 1/2 hour. A total of four arm vein samples were obtained, one before and after each pumping period. Although, in retrospect, the 1/2-hour rest period was inadequate to permit the subjects to return to basal conditions, statistically significant decreases in euglobin lysis time (P = 0.05) occurred with the long boots. This study shows intermittent calf compression increases fibrinolytic potential locally and this effect can be demonstrated systemically. The greater the volume of tissue compressed, the greater the response. The efficacy of intermittent venous compression in reducing the incidence of deep venous thrombosis may be due, in part, to localized induction of fibrinolysis.

Culture fluids from five murine sarcomas were chemotactic for syngeneic peritoneal macrophages in vitro. Peritoneal macrophages from mice infected with Mycobacterium bovis, strain Bacillus Calmette-Guérin, were more responsive to the chemotactic factor in tumor cultures than were normal macrophages. Peritoneal granulocytes, however, did not significantly respond to this factor. The level of chemotactic activity in tumor cultures paralleled cell growth for all five tumors; maximal levels occurred during log growth. Culture medium alone or fluids from proliferating spleen cell cultures stimulated with mitogens did not have detectable chemotactic activity. Chromatography of the tumor culture fluids resulted in a single peak of chemotactic activity in the 15,000-molecular weight range on Sephadex G-100 and at about 7.5 mmho/cm specific conductance on diethylaminoethyl cellulose. By both biological and physicochemical characteristics, the chemotactic activity in tumor culture fluids was different from mouse lymphocyte-derived chemotactic factor.

The level of resistance to infection with Plasmodium chabaudi is genetically controlled. We have previously reported that a single dominant gene is responsible for the variation in host resistance to malaria between susceptible A/J- and resistant C57BL-derived mice. In the present study, recombinant inbred strain analysis was performed with AXB/BXA recombinant inbred strains derived from A/J and C57BL/6 progenitors. Typing of 17 AXB/BXA recombinant inbred strains confirmed the unigenic control of inheritance in this particular strain combination and allowed us to demonstrate genetic linkage between the traits of resistance (defined as a prolonged survival and a low peak parasitemia) and the magnitude of splenomegaly. The influence of sex on the course of infection, which we previously reported in the examination of segregating populations (Stevenson et al., Infect. Immun. 38:80-88, 1982), was again demonstrated in the survey of RI strains.

The level of resistance to infection in inbred mice with the murine malaria species Plasmodium chabaudi AS is genetically determined. Resistant C57BL/6, which are able to eliminate the parasite by 4 weeks, develop marked splenomegaly and survive the infection. Susceptible A/J mice, which succumb to infection (mean survival time = 10 days), develop only minimal splenomegaly. In order to determine if gross differences in the organization, number, and type of spleen cells are related to the outcome of infection with P. chabaudi AS, the development of splenomegaly was examined by enzyme and immunohistochemical methods during the first week after infection. Cryostat sections of spleens removed from normal animals of both strains and at 4 and 7 days after intraperitoneal infection with 10(6) parasitized erythrocytes were stained for enzyme (acid phosphatase and nonspecific esterase) and immunohistochemistry with conventional monoclonal antibodies against T cells, B cells, and macrophages as well as with novel rat anti-mouse monoclonal antibodies which define discrete subpopulations of macrophages in the mouse spleen. The livers of normal and infected animals of each strain were also examined. The results of this study demonstrate (1) differences between normal, uninfected B6 and A/J mice in the organization and number of one subpopulation of macrophages in the spleen, the marginal metallophilic macrophages, and (2) marked histological changes in the spleen and liver during the course of infection in both resistant C57BL/6 and susceptible A/J mice. These changes include depletion of cells from the marginal zone of the spleen which, in the case of the marginal metallophilic macrophages, appears to be more severe in susceptible A/J mice.

The in vitro chemotactic responses of peritoneal macrophages from mice bearing transplantable syngeneic 3-methylcholanthrene-induced tumors in their footpads were depressed to about 50% of normal levels. This chemotactic defect to both lymphocyte- and complement-derived stimuli was evident before the appearance of palpable tumor (within 1 week of tumor injection) and persisted until the death of the animal by 6-8 weeks. Chemotactic depression was not observed with macrophages from mice treated with tissue culture medium, fetal calf serum, incomplete Freund's adjuvant, or syngeneic spleen cells.

The modulation of murine host resistance to infection with Listeria monocytogenes by the substituted pyrimidine anti-viral compounds, 2-amino-5-bromo-6-methyl-4-pyrimidinol (ABMP), 2-amino-5-bromo-6-phenyl-4-pyrimidinol (ABPP) and 2-amino-5-iodo-6-phenyl-4-pyrimidinol (AIPP) was investigated. BAF1 mice given three daily injections of ABMP, ABPP (as well as of the interferon-inducer poly I:C) demonstrated enhanced anti-listerial resistance, as measured by a 100-fold increase in the median lethal dose of Listeria compared to vehicle-treated control mice. This enhancement was also detectable as a decrease (up to 100-fold) in the number of viable Listeria recoverable from the livers and spleens of mice during the non-immune phase of natural resistance (24-72 h following infection) to this pathogen. In contrast, AIPP did not enhance anti-listerial resistance. Since each of the effective agents have been shown to induce the production of interferon, the role of interferon in the mechanism of natural resistance to Listeria was evaluated. The serum of untreated B10.A mice infected with Listeria was shown to contain high levels of interferon. Treatment of these mice with a potent anti-mouse interferon antibody preparation completely neutralized circulating interferon activity; however, such treatment had no apparent effect on the growth of Listeria. In addition, mice which received injections of both ABMP and anti-interferon demonstrated a level of resistance identical to that seen in mice given ABMP and normal serum. Based on these results, we propose that although interferon is produced in response to listerial infection, interferon is not a critically important mediator in the mechanism of natural resistance to this pathogen. Furthermore, it appears that the immunomodulating activity of these experimental compounds does not involve interferon.

The accumulation of inflammatory macrophages at the infective foci appears to represent the major host defense mechanism during the early or innate phase of resistance to infection with Listeria monocytogenes. Certain inbred strains of mice, such as A/J [A] have genetically-determined defects in macrophage mobilization in vivo in response to intraperitoneal (IP) treatment with the nonspecific inflammatory stimulus, thioglycollate. These strains of mice are also genetically-susceptible to infection with Listeria. In contrast, other strains (C57BL/6J or B10.A/SgSn [B]) are high responders for both genetically-determined traits. Linkage analysis of the two traits in backcross progeny showed that the trait of a high macrophage inflammatory response segregates with the trait of resistance to Listeria. These observations suggested that the gene(s) controlling the level of the macrophage inflammatory response is identical with or linked to the gene(s) controlling resistance to Listeria. We have found additional evidence to support this hypothesis by analyzing the expression of the two traits in 12 AXB/BXA recombinant inbred [RI] mouse strains derived from progenitor B (high macrophage response, Listeria-resistant) and A (low macrophage response, Listeria-susceptible) mice. Furthermore, those AXB/BXA strains, which like progenitor A mice, are susceptible to infection with Listeria exhibit a defect in the number of polymorphonuclear leukocytes recovered from peritoneal exudates 18 h after IP injection with thioglycollate. The strain distribution pattern of both the resistance/susceptibility to Listeria and the leukocyte inflammatory response in RI strains is concordant with that of Hc allele coding for effective/defective levels of C5 complement protein.(ABSTRACT TRUNCATED AT 250 WORDS)