The design and synthesis of potent cyclic peptide VCAM-VLA-4 antagonists incorporating an achiral Asp-Pro mimetic

The Asp-Pro sequence of the cyclic peptide Ac-HN-Tyr-Cys*-Asp-Pro-Cys*-OH (1) could be replaced with the achiral dipeptide mimetic 1-(2-aminoethyl)cyclpentylcarboxylic acid with retention of potent inhibition of the VCAM-VLA-4 interaction.

Multifocal osteogenic sarcoma in Paget's disease

The most serious complication of Paget's disease is sarcomatous degeneration of pagetic bone. Multifocal sarcomatous degeneration occurs mainly in polyostotic Paget's disease. Multifocal Paget's sarcoma is uncommon and can arise in any site. We report two cases of synchronous multifocal sarcomatous degeneration. The two patients were elderly women (aged 77 and 86 years, respectively) who developed sarcomatous lesions concomitantly, in the first case report in left ilium, left tibia, and first lumbar vertebra and in the second case report in the skull, right ilium, and sacrum. Whether these cases are due to the simultaneous development of several primaries or to metastases from a single primary remains unclear.

Coinfection of fibroblasts with Coxiella burnetti and Toxoplasma gondii: to each their own

Intracellular pathogens have evolved distinct strategies to subvert host cell defenses. At diametrically opposed ends of the spectrum with regard to the host endosomal/lysosomal defenses are the obligate intracellular protozoan Toxoplasma gondii and the bacterium Coxiella burnetti. While the intracellular replication of T. gondii requires complete avoidance of the host endocytic cascade, C. burnetti actively subverts it. This results in these organisms establishing and growing in very different vacuolar compartments. In this study we examined the potential interaction between these distinct compartments following coinfection of mammalian fibroblasts. When present within the same cell, these organisms exhibit minimal interaction with each other. Colocalization of T. gondii and C. burnetti within the same vacuole occurs at a low frequency in doubly infected cells. In such instances only one of the organisms appears to be replication competent, emphasizing the different requirements for survival and/or intracellular growth. The potential basis for both the lack of interaction between these distinct pathogen-containing compartments, and the mechanisms to address their low frequency of colocalization are discussed in the context of our understanding of the biology of the organisms and membrane traffic in eukaryotic cells.

N-benzylpyroglutamyl-L-phenylalanine derivatives as VCAM/VLA-4 antagonists

A series of N-(N-benzylpyroglutamyl)-4-substituted-L-phenylalanine derivatives was prepared as VLA-4/VCAM antagonists. Analogues substituted by electron deficient benzoylamino groups bearing bulky ortho substituents had low-nM potency in an ELISA assay and low-microM activity in a cell based assay.

Strong human immunodeficiency virus (HIV)-specific CD4+ T cell responses in a cohort of chronically infected patients are associated with interruptions in anti-HIV chemotherapy

Virus-specific CD4+ T-helper cell function is important in controlling human immunodeficiency virus (HIV) infection but is impaired in patients with progressive HIV disease. It has been reported that after highly active antiretroviral therapy (HAART), HIV-specific lymphoproliferative responses remain absent, whereas responses to non-HIV microbial antigens are restored. However, in analyzing immune responses in a cohort of chronically infected adults on HAART, we observed strong HIV-specific CD4+ T cell responses of Th-1 phenotype in 11 of 22 patients. The magnitude and frequency of HIV-specific lymphoproliferative responses was strongly associated with previous interruptions in HAART (P=.001). In contrast, the magnitude of CD8+ T cell responses to HIV Gag, Pol, Env, and Nef was similar in patients who had and those who had not interrupted HAART. We conclude that (1) a significant proportion of chronically HIV-infected patients on HAART can generate strong HIV-specific CD4+ and CD8+ T cell immunity and (2) transient interruptions in antiviral treatment may prime or boost HIV-specific CD4+ T-helper responses.

Dynamic MR imaging of the pelvic floor in asymptomatic subjects

OBJECTIVE

Dynamic MR imaging may be used as an alternative to dynamic cystoproctography for the evaluation of pelvic floor prolapse and configuration. MR criteria for normality are derived from proctographic studies because no large MR study of asymptomatic individuals has been performed. Our study aimed to define the normal range of dynamic pelvic MR appearances in a large group of asymptomatic individuals.

SUBJECTS AND METHODS

Fifty healthy adult volunteers (25 men and 25 women; age range, 20-66 years; mean age, 34 years) were prospectively recruited and examined using dynamic MR imaging. All subjects were interviewed and established as healthy using a validated questionnaire. Axial, coronal, and sagittal MR imaging was performed at rest and during maximum pelvic strain using a static 1.0-T unit and a fast-field-echo sequence, providing 10 slices in 31 sec. Standardized measurements of pelvic configuration were taken, and rest and strain imaging were compared to determine the range of normal appearances.

RESULTS

Three women developed a cystocele during maximum pelvic strain, two of whom also showed grade 1 uterocervical prolapse, which was also seen in another woman. Three men showed posterior pelvic floor descent in excess of 3 cm during straining. No rectocele, enterocele, rectal prolapse, or perineal hernia was seen in any subject.

CONCLUSION

The normal range of pelvic organ descent in asymptomatic subjects seen on dynamic MR imaging included cystocele, uterocervical prolapse, and excessive anorectal junction descent. Although we encountered pelvic prolapse in seven volunteers, it was infrequent and low grade, suggesting that criteria for abnormality derived from proctography are generally applicable to MR imaging.

Thalidomide-induced antigen-specific immune stimulation in patients with human immunodeficiency virus type 1 and tuberculosis

Thalidomide, which inhibits monocyte tumor necrosis factor (TNF)-alpha production and costimulates T cells, was tested for immune modulation in patients with human immunodeficiency virus (HIV) infection and tuberculosis (TB) in a placebo-controlled study. Thalidomide therapy resulted in increased levels of plasma interleukin (IL)-2 receptor, soluble CD8, interferon-gamma, and IL-12, indicating immune stimulation. TNF-alpha levels were not reduced. Thalidomide treatment increased CD4+ and CD8+ T cell counts and lymphocyte proliferation to purified protein derivative. Immune stimulation was not associated with an increase in plasma HIV levels. In vivo, a thalidomide dose-dependent costimulatory effect on T cell proliferation and HIV replication was observed after stimulation with antigens or anti-CD3, respectively. Thalidomide-induced increased viral replication in CD4+ T cells was abrogated by adding back autologous CD8+ T cells. Thus, in the presence of thalidomide, antigen-specific immune responses in vitro and in patients with HIV/TB were enhanced.

Body mass index in 17-year-old Israeli males of different ethnic backgrounds; national or ethnic-specific references?

OBJECTIVE

To evaluate whether a single national reference is appropriate for assessing prevalence of overweight in heterogeneous populations, or whether ethnic-specific references are needed.

DESIGN

A population-based study of Israeli Jewish males who underwent routine physical and clinical examinations prior to army recruitment served as the basis for the development of two types of references for body mass index (BMI): a national reference (NR) and an ethnic-specific reference (ER).

SUBJECTS

Consecutive cohorts of all 17-y-old Jewish male recruits (n=109, 570).

MEASUREMENTS

Weight, height and blood pressure values were obtained. BMI was calculated, and the 85th percentile of BMI was used as a cut-off point for overweight, using both types of references. Prevalence of hypertension among recruits was used as a biomarker to support the reliability of the ER when discrepancy in classification between the two references was found.

RESULTS

As compared to the NR, three ethnic groups had a BMI distribution shifted to the left (light sub-population) and five were shifted to the right (heavy sub-population). In the light sub-population, 7% of the inductees who were classified as having normal weight by the NR were considered overweight by the ER and had a hypertension rate similar to that of those defined as overweight by both references (3.1 per 1000). In the heavy sub-population the 4% of subjects who were overweight by NR and normal by ER had hypertension rates similar to those defined as normal weight by both references (2.7/1000), and significantly lower than that of those classified as overweight by both references (10.8/1000).

CONCLUSION

In heterogeneous populations, ethnic references should be used to evaluate prevalence of overweight, rather than one national reference. International Journal of Obesity (2000)24, 88-92

Marked elevation of serum N-acetyl-beta-D-hexosaminidase activity in rheumatoid rheumatoid arthritis

OBJECTIVE

To study N-acetyl-beta-D-hexosaminidase (NAHase) activity in the sera of rheumatoid arthritis (RA) patients and to determine its source.

METHODS

NAHase activity in the serum and synovial fluid of RA patients was measured with p-nitrophenyl beta-N-acetylglucosaminide as substrate. The p-nitrophenol released was measured spectrophotometrically in an ELISA reader. Rabbit articular chondrocytes in primary culture were stimulated with interleukin-1 beta (IL-1 beta).

RESULTS

Serum NAHase activity was higher in 35% of the RA patients than in healthy patients. The median activity was about twice that of the serum of healthy volunteers. RA patients with high serum NAHase activity also had more joint destruction (85%) than those with normal NAHase activity (57%, p < 0.05), but their inflammatory status was similar. The source of NAHase in RA was investigated by assaying it in RA synovial fluids (SF) and measuring its release from articular chondrocytes in primary culture. NAHase activity was detected in all 23 RA SF, at a median concentration that was 2 times that of the serum. NAHase activity in the medium of articular chondrocytes was stimulated by IL-1 beta (p < 0.005 compared to unstimulated cells), suggesting that cartilage is a source of serum and SF NAHase activity.

CONCLUSION

The serum concentration of the matrix hydrolase, NAHase, is higher in destructive RA than in inflammatory RA.

Leadership 99. Interview by Terese Hudson

Cost control, customer service and collaboration among health care sectors rank as top concerns with panelists in H&HN's annual Leadership Report. Efforts to improve community health are a priority, too, but are often frustrated by financial and other constraints. The 16 panelists represent managed care, physicians, and hospitals and health systems.

Parental knowledge of the treatment of fever in children

BACKGROUND

Although the onset of fever in children often prompts parents to seek immediate treatment, the general level of parental knowledge on pediatric fever and administration of antipyretic medications is unknown. Parents without a basic understanding of treatment principles may give their children incorrect doses of medication. Overdosing may cause drug toxicity, while underdosing may lead to unnecessary, repeated clinic and/or emergency room visits.

OBJECTIVES

To assess parental decision-making with regard to treating fever in children, and its effectiveness, and to suggest methods for improving the level of treatment.

METHODS

In this cross-sectional self-reported survey, questionnaires were completed by 650 parents who sought medical assistance for a child under the age of 10 years. Parents represented various socioeconomic levels, educational backgrounds and religious affiliations.

RESULTS

Ninety-six percent of parents treated fevers that reached 38.5 degrees C, and 77.6% treated fevers of only 38 degrees C. Acetaminophen was the treatment of choice for 96% and dipyrone for 4%. Parental sources of information for managing and administering antipyretic drugs were medical personnel (40.7%), mother's or grandmother's experience (30%), and the enclosed leaflet or instructions on the bottle (29.3%). Forty-three percent of the parents administered the recommended dosage (10-20 mg/kg), whereas 24.3% used less and 32.7% used more; 11% exceeded a daily dosage of 120 mg/kg.

CONCLUSIONS

A total of 57% of parents treated children with incorrect doses of antipyretic drugs. In 11% of the children treated, the daily dose was at a level that could cause severe toxicity. Parental knowledge of the treatment of fever must be improved.

Thalidomide analogue CC1069 inhibits development of rat adjuvant arthritis

The cytokine tumour necrosis factor-alpha (TNF-alpha) has been implicated in the aetiology of rheumatoid arthritis in humans as well as of experimental arthritis in rodents. Thalidomide, and to a greater extent the new thalidomide analogue CC1069, inhibit monocyte TNF-alpha production both in vitro and in vivo. The aim of the present study is to establish whether these drugs block production of TNF-alpha as well as IL-2 by rat leucocytes and whether this inhibition affects the development of rat adjuvant arthritis (AA). Cultured splenocytes were stimulated with either lipopolysaccharide (LPS) or concanavalin A (Con A) in the presence of thalidomide, CC1069, or solvent, and the production of TNF-alpha and IL-2 were compared. Next, adjuvant was injected into the base of the tail of rats without or with daily intraperitoneal injections with 100-200 mg/kg per day thalidomide or 50-200 mg/kg per day CC1069. Disease activity, including ankle swelling, hind limb radiographic and histological changes, weight gain, and ankle joint cytokine mRNA levels, were monitored. CC1069, but not the parent drug thalidomide, inhibited in vitro production of TNF-alpha and IL-2 by stimulated splenocytes in a dose-dependent manner. In vivo, a dose-dependent suppression of AA disease activity occurred in the CC1069-treated animals. In contrast, thalidomide-treated rats experienced comparable arthritis severity to placebo-treated animals. There was also a reduction in TNF-alpha and IL-2 mRNA levels in the ankle joints of CC1069-treated rats compared with thalidomide- and placebo-treated arthritic rats. Early initiation of CC1069 treatment suppressed AA inflammation more efficiently than delayed treatment. We conclude that thalidomide, which did not suppress TNF-alpha or IL-2 production in vitro by Lewis rat cells, did not suppress development of rat AA. However, the development of rat AA can be blocked by the thalidomide analogue CC1069, which is an efficient inhibitor of TNF-alpha production and IL-2 in vitro.

Relation between income inequality and mortality: empirical demonstration

OBJECTIVE

To assess the extent to which observed associations at population level between income inequality and mortality are statistical artefacts.

DESIGN

Indirect "what if" simulation by using observed risks of mortality at individual level as a function of income to construct hypothetical state level mortality specific for age and sex as if the statistical artefact argument were 100% correct.

SETTING

Data from the 1990 census for the 50 US states plus Washington, DC, were used for population distributions by age, sex, state, and income range; data disaggregated by age, sex, and state from the Centers for Disease Control and Prevention were used for mortality; and regressions from the national longitudinal mortality study were used for the individual level relation between income and risk of mortality.

RESULTS

Hypothetical mortality, while correlated with inequality (as implied by the logic of the statistical artefact argument), showed a weaker association with states' levels of income inequality than the observed mortality.

CONCLUSIONS

The observed associations in the United States at the state level between income inequality and mortality cannot be entirely or substantially explained as statistical artefacts of an underlying individual level relation between income and mortality. There remains an important association between income inequality and mortality at state level over and above anything that could be accounted for by any statistical artefact. This result reinforces the need to consider a broad range of factors, including the social milieu, as fundamental determinants of health.

Group B streptococcal vertebral osteomyelitis with bacteraemia in an adult with no debilitating condition

A previously healthy 62-year-old immunocompetent woman presented with group B streptococcal vertebral osteomyelitis. Group B Streptococcus was recovered in 3 consecutive blood cultures. The patient recovered fully after treatment including antibiotic therapy, bed rest and physical rehabilitation. Group B streptococcal vertebral osteomyelitis is uncommon and has not previously been reported in patients with no immunosuppressive condition.

Thalidomide stimulates T cell responses and interleukin 12 production in HIV-infected patients

We performed a placebo-controlled study to evaluate the effects of immunomodulatory treatment with thalidomide on HIV levels, TNF-alpha levels, and immune status of 31 HIV-infected individuals, after temporary suppression of viral replication with antiretroviral drugs. Treatment with a combination of zidovudine and lamivudine (ZDV/LMV) for 14 days resulted in a median decline in plasma viremia of 1.94 log10 RNA equivalents/ml. After discontinuation of ZDV/LMV, thalidomide therapy (200 mg/day for 4 weeks) did not retard the prompt return of HIV titers to the pretreatment levels, and had no effect on plasma levels of TNF-alpha. In contrast, thalidomide treatment resulted in significant immune stimulation. We observed increased levels of plasma soluble IL-2 receptor, soluble CD8 antigen, and IL-12 (p < 0.01 for all parameters), as well as increased cutaneous delayed-type hypersensitivity reactions to recall antigens (p < 0.01) in thalidomide-treated patients. These changes were associated with a median increase in HIV titer of 0.2 log10 RNA equivalents/ml in the thalidomide-treated group (p < 0.05), which resolved after stopping the drug. Further studies were performed in vitro to elucidate the mechanism of thalidomide-induced immune stimulation. When purified T cells from HIV-infected individuals were stimulated by immobilized anti-CD3 in the presence of thalidomide, a costimulatory effect of the drug was observed, resulting in increased production of IL-2 and IFN-gamma, and increased T cell-proliferative responses. Further experiments showed that thalidomide increased IL-12 production by antigen-presenting cells in a T cell-dependent manner. Our findings suggest a potential application for thalidomide as a novel immune adjuvant in HIV disease.

Differential cytokine modulation and T cell activation by two distinct classes of thalidomide analogues that are potent inhibitors of TNF-alpha

TNF-alpha mediates both protective and detrimental manifestations of the host immune response. Our previous work has shown thalidomide to be a relatively selective inhibitor of TNF-alpha production in vivo and in vitro. Additionally, we have recently reported that thalidomide exerts a costimulatory effect on T cell responses. To develop thalidomide analogues with increased anti-TNF-alpha activity and reduced or absent toxicities, novel TNF-alpha inhibitors were designed and synthesized. When a selected group of these compounds was examined for their immunomodulatory activities, different patterns of cytokine modulation were revealed. The tested compounds segregated into two distinct classes: one class of compounds, shown to be potent phosphodiesterase 4 inhibitors, inhibited TNF-alpha production, increased IL-10 production by LPS-induced PBMC, and had little effect on T cell activation; the other class of compounds, similar to thalidomide, were not phosphodiesterase 4 inhibitors and markedly stimulated T cell proliferation and IL-2 and IFN-gamma production. These compounds inhibited TNF-alpha, IL-1beta, and IL-6 and greatly increased IL-10 production by LPS-induced PBMC. Similar to thalidomide, the effect of these agents on IL-12 production was dichotomous; IL-12 was inhibited when PBMC were stimulated with LPS but increased when cells were stimulated by cross-linking the TCR. The latter effect was associated with increased T cell CD40 ligand expression. The distinct immunomodulatory activities of these classes of thalidomide analogues may potentially allow them to be used in the clinic for the treatment of different immunopathological disorders.

Survival of Mycobacterium avium and Mycobacterium tuberculosis in acidified vacuoles of murine macrophages

Despite the antimicrobial mechanisms of vertebrate phagocytes, mycobacteria can survive within the phagosomes of these cells. These organisms use various strategies to evade destruction, including inhibition of acidification of the phagosome and inhibition of phagosome-lysosome fusion. In contrast to mycobacteria, Coxiella burnetii, the etiologic agent of Q fever, inhabits a spacious acidified intracellular vacuole which is prone to fusion with other vacuoles of the host cell, including phagosomes containing mycobacteria. The Coxiella-infected cell thus provides a unique model for investigating the survival of mycobacteria in an acidified phagosome-like compartment. In the present study, murine bone marrow-derived macrophages were infected with either Mycobacterium avium or Mycobacterium tuberculosis and then coinfected with C. burnetii. We observed that the majority of phagocytosed mycobacteria colocalized to the C. burnetii-containing vacuole, which maintained its acidic properties. In coinfected macrophages, the growth of M. avium was not impaired following fusion with the acidified vacuole. In contrast, the growth rate of M. tuberculosis was reduced in acidified vacuoles. These results suggest that although both species of mycobacteria inhibit phagosome-lysosome fusion, they may be differentially susceptible to the toxic effects of the acidic environment in the mature phagolysosome.

[Gougerot-Sjögren syndrome. Diagnostic criteria and therapeutic methods]

CLASSIFICATION CRITERIA: Several systems of classification criteria have been developed for Sjögren's syndrome. These systems allow patient classification but do not constitute diagnostic criteria. The most widely used is based on the Fox criteria which are totally specific but have low sensitivity. The European criteria have satisfactory sensitivity and specificity.

IN CLINICAL PRACTICE

In all cases, the elements comprising the sicca syndrome must be identified. A labial biopsy for histology of the accessory salivary glands may be helpful. A less extensive search is sometimes sufficient if the aim is uniquely diagnostic. TREATMENT OF SJOGREN'S SYNDROME: Symptomatic treatment of the sicca syndrome with local procedures is aimed at reducing the functional disorder. The systemic route is used to treat the dysimmune component. As in most connective tissue diseases, most patients can be stabilized, limiting the functional consequences of the disease, but cure remains illusive.

Amino-substituted thalidomide analogs: potent inhibitors of TNF-alpha production

Thalidomide, (1), is a known inhibitor of TNF-alpha release in LPS stimulated human PBMC. Herein we describe the TNF-alpha inhibitory activity of amino substituted analogs of thalidomide (1) and its isoindolin-1-one analog, EM-12 (2). The 4-amino substituted analogs were found to be potent inhibitors of TNF-alpha release in LPS stimulated human PBMC.

Mycobacterium tuberculosis CDC1551 induces a more vigorous host response in vivo and in vitro, but is not more virulent than other clinical isolates

Mycobacterium tuberculosis CDC1551, a clinical isolate reported to be hypervirulent and to grow faster than other isolates, was compared with two other clinical isolates (HN60 and HN878) and two laboratory strains (H37Rv and Erdman). The initial (1-14 days) growth of CDC1551, HN60, HN878, and H37Rv was similar in the lungs of aerosol-infected mice, but growth of Erdman was slower. Thereafter, the growth rate of CDC1551 decreased relative to the other strains which continued to grow at comparable rates up to day 21. In the lungs of CDC1551-infected mice, small well-organized granulomas with high levels of TNF-alpha, IL-6, IL-10, IL-12, and IFN-gamma mRNA were apparent sooner than in lungs of mice infected with the other strains. CDC1551-infected mice survived significantly longer. These findings were confirmed in vitro. The growth rates of H37Rv and CDC1551 in human monocytes were the same, but higher levels of TNF-alpha, IL-10, IL-6, and IL-12 were induced in monocytes after infection with CDC1551 or by exposure of monocytes to lipid fractions from CDC1551. CD14 expression on the surface of the monocytes was up-regulated to a greater extent by exposure to the lipids of CDC1551. Thus, CDC1551 is not more virulent than other M. tuberculosis isolates in terms of growth in vivo and in vitro, but it induces a more rapid and robust host response.

Thalidomide and a thalidomide analogue inhibit endothelial cell proliferation in vitro

Angiogenesis is a crucial process in inflammatory reactions as well as in tumor implantation and growth. Tumors with high rates of invasion and recurrence such as gliomas, are specially dependent on neovascularization. This suggests that inhibition of angiogenesis might reduce the growth of these tumors. Thalidomide has been previously shown to inhibit angiogenesis induced by basic fibroblast growth factor in vivo, using the rabbit corneal micropocket assay. Therefore, the effect of thalidomide and a thalidomide analogue (cc-1069) on the proliferation in vitro of endothelial and glioma cells was tested. We observed a decrease in endothelial cell proliferation in cultures treated with thalidomide or the thalidomide analogue cc-1069. The analogue inhibited endothelial cell proliferation more efficiently than thalidomide. The inhibition occurred in association with a marked decrease in the activity of the nuclear factor SP1 and a moderate inhibition of NF-kappaB activation in nuclear extracts of endothelial cells. The drugs did not impair cell viability. There was no effect of thalidomide or the thalidomide analogue on the proliferation of the glioma cell line (U251) in vitro.

Osteonecrosis-like syndrome of the medial tibial plateau can be due to a stress fracture. MR findings in 13 patients

OBJECTIVE

To demonstrate the contribution of magnetic resonance imaging to the elucidation of mechanisms involved in "osteonecrosis-like syndrome of the medial tibial plateau".

PATIENTS AND METHODS

A magnetic resonance study with sagittal and coronal sections was done in 13 patients (age range, 57-95 years) two weeks to four months into a painful syndrome meeting the definition of "osteonecrosis-like syndrome of the medial tibial plateau". Gadolinium injection was used in nine patients. Clinical symptoms resolved within a few weeks in all 13 cases.

RESULTS

T1-weighted images without gadolinium showed diffuse low signal from the epiphysis (n = 12) containing an area of even lower signal seen either as a crescent-shaped subchondral image (n = 3/12) or as a linear image (n = 9/12). On postgadolinium images, the low signal was abolished except for a line of low signal parallel to the subchondral bone. T2-weighted images demonstrated diffuse high signal from the medial tibial plateau with persistence of the line of low signal (n = 8/12).

CONCLUSION

Magnetic resonance imaging allows to analyze the anatomic lesion responsible for "osteonecrosis-like syndrome of the medial tibial plateau". Our magnetic resonance findings were similar to those seen in stress fractures at other sites.

Tumor necrosis factor alpha is a determinant of pathogenesis and disease progression in mycobacterial infection in the central nervous system

The pathogenesis of tuberculous meningitis, a devastating complication of tuberculosis in man, is poorly understood. We previously reported that rabbits with experimental tuberculous meningitis were protected from death by a combination of antibiotics and thalidomide therapy. Survival was associated with inhibition of tumor necrosis factor alpha (TNF-alpha) production by thalidomide. To test whether cerebrospinal fluid (CSF) levels of TNF-alpha correlated with pathogenesis, the response of rabbits infected in the central nervous system (CNS) with various mycobacterial strains was studied. CNS infection with Mycobacterium bovis Ravenel, M. bovis bacillus Calmette-Guérin (BCG) Pasteur, and M. bovis BCG Montreal were compared. M. bovis Ravenel induced the highest levels of TNF-alpha in the CSF in association with high leukocytosis, protein accumulation, and severe meningeal inflammation. BCG Pasteur had intermediate effects, and BCG Montreal was the least virulent. In addition, M. bovis Ravenel numbers were highest in the brain and CSF and the bacilli also disseminated more efficiently to distant organs, compared with BCG Pasteur and BCG Montreal. In subsequent experiments, rabbits were infected with either recombinant M. bovis BCG Montreal (vector), or BCG Montreal expressing the murine gene for TNF-alpha (BCG mTNF-alpha). BCG Montreal was rendered virulent by the expression of murine TNF-alpha, as demonstrated by high CSF leukocytosis, high protein accumulation, severe meningeal inflammation, persistent bacillary load, and progressive clinical deterioration. Taken together, these results demonstrate that the level of TNF-alpha produced during mycobacterial CNS infection determines, at least in part, the extent of pathogenesis.