Ergonomics, musculoskeletal disorders, treatment and return to work: a conceptual framework for intervention programs

Musculoskeletal disorders are one of the most recurrent diseases among manual workers worldwide. The objective of this study was to analyze primary results of a systematic review on ergonomics, musculoskeletal disorders, treatment, and return to work in blue-collar workers to form a new conceptual framework applicable to intervention programs in this area. This study was based on the available scientific evidence we identified. Descriptive data and their trending topics areas were used to form the conceptual framework. The trend shows that working conditions can be represented as a three-axis scheme with a multidimensional conceptual framework considering ergonomic risks, the treatment of affected workers and the determinants related to working conditions. These results may help future research in the field of ergonomics as well as emerging topics focused on intervention programs.

Leaving no-one behind in the workplace health promotion: towards regulatory equity in the Ecuadorian micro-enterprises

The purpose of workplace public health programmes and regulations is to promote safety and health for the entire working population nationwide. Some countries limit the scope of such programmes to medium or big-sized companies, leaving out small and micro-enterprises, thus discriminating against many workers exposed to risks. This Viewpoint aims to identify inequalities in occupational health generated by the new Regulation for Workplace Health Promotion (WHP) in Ecuador. We showed how the regulation excludes all micro-enterprises and displayed the essential role of micro-enterprises in the business fabric and the Ecuadorian labour market. More than 93% of the registered companies are micro-enterprises and these include more than 25% of the employees in the formal economy. Integrating occupational health into the public health system will require deep analysis to improve protection for the working population.

Mapping the conceptual structure of ergonomics, musculoskeletal disorders, treatment and return to work in manual jobs: A systematic review

BACKGROUND

Musculoskeletal disorders constitute one of the major health problems of workers exposed to manual work throughout the world. Nevertheless, there is no study that maps its conceptual structure based on a systematic methodology.

OBJECTIVE

To identify the conceptual structure of ergonomics, MSDs, treatment and return to work in manual jobs in the last 12 years by applying a systematic co-word network analysis methodology which describes the replicability of the search filters and emphasizes the rigor that has to be followed in the creation of the network.

METHODS

The search filter was customized for each bibliographic database, and followed the PRISMA 2020 flowchart for the screening process. For the creation of the network, the titles, abstracts, and keywords were used as the unit of analysis extracting the noun phrases of the first two units. In the normalization process, the terms of the search filter were deleted and their associated terms, and standardized the similar terms. Regarding the plotting of the network, Vosviewer was used applying the network settings based on content analysis.

RESULTS

The co-word network shows three communities: Ergonomic assessment and workplace intervention tools, factors related to rehabilitation and return to work, and physical and mental overload management. For each community, there is a framework that explains the relationship within terms.

CONCLUSION

This study is aligned with the replicability, robustness, and relevance recommendations in the implementation of rigorous scientometric studies. The occupational health community is encouraged to implement scientometric studies following a rigorous methodology and working in interdisciplinary team.

CRS-related coagulopathy in BCMA targeted CAR-T therapy: a retrospective analysis in a phase I/II clinical trial

Chimeric antigen receptor (CAR) T-cell therapy that targets B-cell maturation antigen (BCMA) has shown promising effects in the treatment of patients with refractory/relapsed multiple myeloma (R/R MM) patients. In this retrospective analysis of phase I/II clinical trial (ChiCTR1800017404), 37 patients with R/R MM received their first BCMA-targeted CAR T-cells following lymphodepletion chemotherapy. The response rate was high (97%), while accompanied by a high incidence of adverse events including coagulation dysfunction. Of 37 patients, all (100%) had cytokine release syndrome (CRS) and 34 (91%) developed at least one abnormal coagulation parameter. The values of coagulation parameters were positively correlated with the severity of CRS as well as with the levels of some cytokines, such as interleukin (IL)-6, IL-10, and interferon (IFN)-γ, etc. Furthermore, levels of the plasma tissue factor (TF), Factor X (FX), Factor XII (FXII), and P-selectin also showed a positive correlation with severity of CRS as well as some specific cytokines, which indicates that these factors are likely to play important roles in CRS-related coagulopathy. Our study suggests that there exists relationship in some extent between coagulation disorder and CRS. Moreover, coagulation dysfunction can be managed with daily monitoring and early intervention despite high incidence.

Isoniazid therapy for Mycobacterium tuberculosis infection in HIV clinics, Los Angeles, California

SETTING

Publicly funded human immunodeficiency virus (HIV) clinics in Los Angeles County, California, USA.

BACKGROUND

HIV-infected persons are a high priority group for targeted testing and treatment for Mycobacterium tuberculosis infection in the United States.

OBJECTIVE

To describe rates of isoniazid (INH) initiation and completion among HIV-1 and M. tuberculosis co-infected persons in Los Angeles County.

DESIGN

We conducted a cross-sectional study using routinely collected surveillance data from publicly funded HIV clinics. We examined differences in INH treatment initiation and completion between four clinic categories: the three largest clinics (Clinics A, B, and C) and 'Other' clinics (pooled data for the remaining 10 clinics).

RESULTS

During 2010-2013, 802 (5.3%) of 15 029 HIV-1-infected persons tested positive for M. tuberculosis infection. INH was initiated in 581 (72.4%) persons, of whom 457 (78.7%) completed treatment. We found significant differences between clinics in terms of treatment initiation (range 59.1-93.4%) and completion (range 58.8-82.3%). Overall, 57% (457/802) of HIV and M. tuberculosis co-infected persons completed the recommended treatment (range across clinics 34.8-76.3%).

CONCLUSION

We identified significant gaps in the treatment for M. tuberculosis infection among HIV-infected persons in Los Angeles County. Interventions are needed to improve initiation and completion of treatment for M. tuberculosis infection in this population.

Association of baseline knee sagittal dynamic joint stiffness during gait and 2-year patellofemoral cartilage damage worsening in knee osteoarthritis

OBJECTIVE

Knee sagittal dynamic joint stiffness (DJS) describes the biomechanical interaction between change in external knee flexion moment and flexion angular excursion during gait. In theory, greater DJS may particularly stress the patellofemoral (PF) compartment and thereby contribute to PF osteoarthritis (OA) worsening. We hypothesized that greater baseline knee sagittal DJS is associated with PF cartilage damage worsening 2 years later.

METHODS

Participants all had OA in at least one knee. Knee kinematics and kinetics during gait were recorded using motion capture systems and force plates. Knee sagittal DJS was computed as the slope of the linear regression line for knee flexion moments vs angles during the loading response phase. Knee magnetic resonance imaging (MRI) scans were obtained at baseline and 2 years later. We assessed the association between baseline DJS and baseline-to-2-year PF cartilage damage worsening using logistic regression with generalized estimating equations (GEE).

RESULTS

Our sample had 391 knees (204 persons): mean age 64.2 years (SD 10.0); body mass index (BMI) 28.4 kg/m² (5.7); 76.5% women. Baseline knee sagittal DJS was associated with baseline-to-2-year cartilage damage worsening in the lateral (OR = 5.35, 95% CI: 2.37-12.05) and any PF (OR = 2.99, 95% CI: 1.27-7.04) compartment. Individual components of baseline DJS (i.e., change in knee moment or angle) were not associated with subsequent PF disease worsening.

CONCLUSION

Capturing the concomitant effect of knee kinetics and kinematics during gait, knee sagittal DJS is a potentially modifiable risk factor for PF disease worsening.

Local epidemic history as a predictor of tuberculosis incidence in Saskatchewan Aboriginal communities

BACKGROUND

Average tuberculosis (TB) incidence rates are high in Canadian Aboriginal communities, but there is significant variability within this group.

OBJECTIVE

To determine whether local history of post-contact TB epidemics is predictive of contemporary epidemiology among Aboriginal communities in Saskatchewan, Canada.

METHODS

TB incidence, age-specific morbidity patterns and rates of clustering of TB genotypes from 1986 to 2004 were compared between two groups of communities: Group 1, in which post-contact epidemics of TB were established around 1870, and Group 2, in which they were delayed until after 1920. Concomitant effects of socio-economic and geographic variables were explored with multivariate models.

RESULTS

Group 2 communities were characterized by higher annual incidence of TB (median 431 per 100,000 population vs. 38/100,000). In multivariate models that included socio-economic and geographic variables, historical grouping remained a significant independent predictor of community incidence of TB. Clustering of TB genotypes was associated with Group 2 (OR 8.7, 95%CI 3.3-22.7) and age 10-34 years (OR 2.5, 95%CI 1.1-5.7).

CONCLUSIONS

TB transmission dynamics can vary significantly as a function of a population's historical experience with TB. Populations at different stages along the epidemic trajectory may be amenable to different types of interventions.

MR imaging of papillary tumor of the pineal region

We report the imaging features of 4 cases of patients with papillary tumor of the pineal region, a tumor newly recognized in the 2007 World Health Organization "Classification of Tumors of the Nervous System." In each case, the tumor was intrinsically hyperintense on T1-weighted images with a characteristic location in the posterior commissure or pineal region. The pathologic hallmarks of the tumor are discussed, including a possible explanation for the MR imaging characteristics in our cases.

Potentiation of opioid analgesia in dopamine2 receptor knock-out mice: evidence for a tonically active anti-opioid system

Dopamine systems are intimately involved with opioid actions. Pharmacological studies suggest an important modulatory effect of dopamine and its receptors on opioid analgesia. We have now examined these interactions in a knock-out model in which the dopamine(2) (D(2)) receptor has been disrupted. Loss of D(2) receptors enhances, in a dose-dependent manner, the analgesic actions of the mu analgesic morphine, the kappa(1) agonist U50,488H and the kappa(3) analgesic naloxone benzoylhydrazone. The responses to the delta opioid analgesic [d-Pen(2),d-Pen(5)]enkephalin were unaffected in the knock-out animals. Loss of D(2) receptors also potentiated spinal orphanin FQ/nociceptin analgesia. Antisense studies using a probe targeting the D(2) receptor revealed results similar to those observed in the knock-out model. The modulatory actions of D(2) receptors were independent of final sigma receptor systems because the final sigma agonist (+)-pentazocine lowered opioid analgesia in all mice, including the D(2) knock-out group. Thus, dopamine D(2) receptors represent an additional, significant modulatory system that inhibits analgesic responses to mu and kappa opioids.

Synthetic explorations towards 3-deoxy-3-fluoro derivatives of D-perosamine

Based on a literature precedent, preparation of methyl 4-azido-3,4,6-trideoxy-3-fluoro-alpha-D-mannopyranoside (18) was attempted via fluorination of methyl 4-azido-2-O-benzyl-4,6-dideoxy-alpha-D-altropyranoside with diethylaminosulfur trifluoride (DAST). Contrary to expectations, the reaction took place with retention of configuration at the site of the fluorination yielding methyl 4-azido-2-O-benzyl-3,4,6-trideoxy-3-fluoro-alpha-D-altropyranoside. Treatment with DAST of methyl 4-azido-2-O-benzyl-4,6-dideoxy-alpha-D-allopyranoside (8), or its 2-(p-methoxybenzyl) analog 9 resulted in fluorination with inversion of configuration at position 3, to give the corresponding 3-deoxy-3-fluoro glucopyranosides 10 and 11, respectively. Accordingly, compound 18 was prepared from 11, by de-p-methoxybenzylation at O-2, followed by inversion of configuration at C-2 in the resulting methyl 4-azido-3,4,6-trideoxy-3-fluoro-alpha-D-glucopyranoside. The 2-O-methyl analog of 18 (19) was prepared by methylation of 18. Compounds 18 and 19 were converted, conventionally, into the 3-fluoro analogs of the terminal determinants of the O-PS of Vibrio cholerae O:1, serotype Inaba and Ogawa, respectively.

Hck SH3 domain-dependent abrogation of Nef-induced class 1 MHC down-regulation

The ability of specific virally encoded proteins to down-regulate MHC class I molecules may enable infected cells to elude killing by CTL. In the case of HIV-1, Nef appears to be responsible for this effect. Thus, interfering with Nef-induced MHC class I down-regulation would be a strategy for increasing HIV-1-specific CTL activity, particularly towards long-lived T cell populations such as memory T cells that harbor replication-competent virus. Here, using two Nef-expressing human cell model systems, we show that a dominant-negative mutant derived from the Hck protein-tyrosine kinase, composed of the Hck N-terminal region, as well as the SH3 and SH2 domains, was able to inhibit Nef-induced MHC class I molecule down-regulation. This effect was SH3 domain dependent as it was not evident when the cells were transfected with DN-Hck-W93F, an SH3 domain mutant. The inhibitory effect of dominant-negative-Hck (DN-Hck) on Nef-induced class I down-regulation suggests that this Nef-mediated effect requires an interaction between the Nef polyproline site and an SH3-containing cellular protein that is involved in MHC class I molecule turnover. Interfering with the function of the Nef SH3 binding site in this way represents a strategy for assisting the host CTL response to clear HIV-1-infected cells.

Ectopic cerebellum presenting as a suprasellar mass in infancy: implications for cerebellar development

A 4-month-old infant with a history of nasopharyngeal teratoma developed progressive optic neuropathy. Neuroimaging studies demonstrated a solid, isointense, suprasellar mass impinging on optic nerves and chiasm superiorly. The mass was subtotally resected. No attachment of the mass to brain stem or cerebellar structures was noted. Histological examination identified the tissue as developing cerebellum. The cytoarchitecture and cellular constituents of the cerebellar tissue were only slightly distorted. All cerebellar cortical constituents were arranged anatomically, and an external granular cell layer was present superficially. The latter was actively proliferating and appropriately cellular for the infant's age. The clinical presentation of ectopic cerebellum as a suprasellar mass in an infant is highly unusual. Moreover, this example illustrates the ability of cerebellar tissue to mature appropriately in a site distant from the posterior fossa, removed from ascending and descending afferent projections. Intrinsic signaling mechanisms appear sufficient to direct histogenesis in developing cerebellar cortex.

Practice-related changes in lumbar loading during rapid voluntary pulls made while standing

OBJECTIVE

To determine if five days of practice on a novel dynamic, multi-joint pulling task resulted in lower magnitudes of lumbar loading or a more consistent relationship between pulling force and lumbar loading.

DESIGN

A repeated measures design compared how practice influenced the magnitude of lumbar torque and the correlations between lumbar torque and pulling force.

BACKGROUND

Previous studies suggest that practice can decrease the magnitude of lumbar loading on simple manual material handling tasks, but it is unknown whether practice reduces lumbar loading for more complex tasks. Neither is it known whether the consistency of lumbar loading increases with practice.

METHODS

Ten healthy adults practiced impulse-like horizontal pulls to targets equaling 20%, 40% and 80% of their estimated maximal dynamic pulling force over 5 days. Movements were unrestrained, other than keeping the feet flat on the ground. We used a four-segment, sagittal plane inverse dynamics model to compute lumbar, hip, knee, and ankle torques on days 1 and 5 from ground reaction forces and moments, pulling forces, and kinematics.

RESULTS

An analysis of variance showed significant practice-related changes in lumbar torque at the time of peak pulling force (lumbar torque(peakPF)). The lumbar torque(peakPF) decreased for the 20% pulls, did not change for the 40% pulls, and increased for the 80% pulls. Two subjects showed a significant decrease in lumbar torque(peakPF) for all three force levels. Coefficients of determination between pulling force and lumbar torque (r(2)(PF,LT): a measure of the consistency of the relationship between these two variables) were significantly higher on day 5 than day 1.

CONCLUSIONS

Practice on a novel pulling task changed the magnitude of lumbar torques and increased their correlation with pulling force, suggesting that subjects learned strategies that improve motor control of lumbar torques. Relevance The study showed that the magnitude and consistency of lumbar loading changed spontaneously as subjects practiced a novel multijoint pulling task. Such changes may decrease the risk of low-back injury.

Effect of age on the refractive outcome of myopic photorefractive keratectomy

PURPOSE

To evaluate the effect of age on the outcome of myopic photorefractive keratectomy (PRK).

SETTING

University-based refractive surgery practice.

METHODS

A retrospective analysis of 197 eyes that had PRK for myopia was performed. Four groups of patients were compared: Group 1, patients < 30 years (n=35); Group 2, patients 31 to 40 years (n=56); Group 3, patients 41 to 50 year s (n=47); Group 4, patients > 50 years (n=59). The percentage of eyes with an uncorrected visual acuity of 20/20 or better and 20/40 or better and the percentage of eyes with spherical correction within +/-0.5 and +/-1.0 diopter (D) of the attempted correction were derived for each age group. The percentage of patients overcorrected and undercorrected by 1.0 D or more in each age group was also calculated. The difference between the percentage of patients who achieved a visual acuity of 20/20 or better in Group 4 and in the younger groups was statistically significant at 3 months (P =.02) but not at 6 months (P =.70) and 12 months (P =.55). The difference between the percentage of patients who achieved an acuity of 20/40 or better was not significant at any time. The difference between the percentage of patients who were within +/-0.5 D of intended correction in Group 4 and in the younger groups was statistically significant at 3 months (P =.001), 6 months (P =.006), and 12 months (P =.008); the difference between the percentage of patients who were within +/-1.0 D of intended correction was not significant at any time. The difference between the percentage of patients overcorrected and undercorrected by 1.0 D or more in Group 4 and in the younger groups was not significant at any time. In the 3 younger groups, age did not significantly affect visual outcome or predictability. However, there was a significant difference between Group 4 and the 3 younger groups in predictability of the refractive outcome at 3, 6, and 12 months. Age may play a role in the outcome of refractive surgery.

Construction of single-chain antibodies that bind an overlapping epitope of HIV-1 Nef

The light and heavy chain variable regions of three mouse hybridoma cell lines (AG11, AE6 and EH1) that produce monoclonal antibodies against an overlapping epitope at the C-terminus of Nef were cloned. Sequence analysis of the light and heavy chain variable regions indicated that clones AG11 and AE6, but not EH1, were highly related. Single-chain antibodies were constructed from the cDNA clones of AG11 and EH1, and subcloned into an eukaryotic expressing vector with the green fluorescent protein as marker for expression. Such intracellular antibodies may provide a way in which to inhibit the function of Nef during HIV-1 infection of cells.

Spinal analgesic activity of orphanin FQ/nociceptin and its fragments

Previous work reveals that orphanin FQ/nociceptin (OFQ/N) administered supraspinally produces an initial hyperalgesic response followed by analgesia. Spinally, OFQ/N elicits a rapidly appearing, naltrexone-reversible, dose-dependent analgesia in the tailflick assay without any indication of hyperalgesia. Two OFQ/N fragments, OFQ/N (1-7) and OFQ/N (1-11), are active, but far weaker. Blockade of sigma receptors with haloperidol enhances the analgesic potency of spinal OFQ/N, OFQ/N (1-7) and OFQ/N (1-11), but not as dramatically as supraspinal OFQ. Antisense probes targeting the second and third coding exons, but not the first exon, of the cloned mouse OFQ/N receptor (KOR-3) partially block OFQ/N analgesia.

Evaluation of a rehabilitative pedorthic: plantar pressure alterations with scaphoid pad application

Scaphoid or longitudinal arch pads are frequently prescribed pedorthics for foot and ankle rehabilitation. These pedorthics are reported to be effective in mechanically supporting the medial longitudinal arch while reducing plantar and medial soft tissue strain. The objective of this study was to measure alterations in ambulatory plantar pressure metrics in a group of adults secondary to scaphoid pad application. The biomechanical rationale of this study was that the geometry of foot contact would be altered secondary to foot inversion. Ten adult male subjects with biomechanically normal feet were evaluated during multiple trials. A Holter type microprocessor-based portable in-shoe plantar pressure data acquisition system was used to record the dynamic data. Pressures were recorded from eight discrete plantar locations at the hindfoot, midfoot, and forefoot regions of the insole. Statistically significant (p < or = 0.05) increases in peak pressures were seen laterally with scaphoid pad application, while significant decreases in peak pressures with pad usage occurred at the hallux and the calcaneal region of the foot. At the medial longitudinal arch, peak pressures increased from near 0 to 115.3 kPa, contact durations increased from near 0 to 438 ms, and pressure-time integrals increased from near 0 to 33.4 kPa.s.

Inhibition of the self-cleavage reaction of the human hepatitis delta virus ribozyme by antibiotics

Human hepatitis delta virus (HDV) poses a health threat in populations where chronic hepatitis B is endemic. It is a single-stranded RNA virus of 1700 nucleotides and both genomic and antigenomic sequences contain ribozymes which are important for viral replication. Using ribozyme constructs we show that several classes of antibiotics inhibit the self-cleavage reaction of the HDV ribozyme. Antibiotics of the aminoglycoside, peptide and tetracycline classes all inhibit HDV cleavage in vitro at micromolar concentrations. Neomycin (an aminoglycoside) inhibits HDV self-cleavage with a Ki value of 28 (+/- 10) microM. Neomycin inhibition can be reversed by increasing magnesium ion concentration in a competitive manner. Lead acetate cleaves positions G76, A42 and G28, which surround the ribozyme cleavage site. Both Mg2+ and neomycin prevent lead cleavage. Footprinting experiments using base-specific chemical probes revealed enhanced modifications of a set of bases by neomycin, overlapping with the above mentioned lead cleavages. These observations may indicate that neomycin directly displaces divalent metal ions essential for catalysis.

[Ender nailing of humeral shaft fractures]

From March 1991 to June 1992, thirteen patients with humeral shaft fracture were managed at our hospital with closed reduction and internal fixation with Ender nails. These patients were mainly victims of traffic accidents and falls and had fractures, head injuries, and chest trauma. The follow-up period was more than 1 year. Operations were performed under C-arm guide and, according to the method of Hall and Pankovich, divided into antegrade and retrograde methods. The average operation time was 104 minutes, ranging from 70 to 160 minutes, and blood loss was less than 100 ml. Twelve patients were available for follow-up with 11 unions (91.6%), and the functional results were satisfactory. Complications included 2 nails backing out and one iatrogenic fracture. There was no infection and no radial nerve injury. We concluded that for those humeral shaft fractures with surgical indication, Ender nailing was a good choice. The advantages include a simple procedure, lower infection rate and less nonunions.

Multistep measurement of plantar pressure alterations using metatarsal pads

Metatarsal pads are frequently prescribed for nonoperative management of metatarsalgia due to various etiologies. When appropriately placed, they are effective in reducing pressures under the metatarsal heads on the plantar surface of the foot. Despite the positive clinical reports that have been cited, there are no quantitative studies documenting the load redistribution effects of these pads during multiple step usage within the shoe environment. The objective of this study was to assess changes in plantar pressure metrics resulting from pad use. Ten normal adult male subjects were tested during a series of 400-step trials. Pressures were recorded from eight discrete plantar locations at the hindfoot, midfoot, and forefoot regions of the insole. Significant increases in peak pressures, contact durations, and pressure-time integrals were noted at the metatarsal shaft region with pad use (P < or = .05). Statistically significant changes in metric values were not seen at the other plantar locations, although metatarsal pad use resulted in mild decreases in mean peak pressures at the first and second metatarsal heads and slight increases laterally. Contact durations decreased at all metatarsal head locations, while pressure-time integrals decreased at the first, second, third, and fourth metatarsal heads. A slight increase in pressure-time integrals was seen at the fifth metatarsal head. The redistribution of plantar pressures tended to relate not only to the dimensions of the metatarsal pads, but also to foot size, anatomic foot configuration, and pad location. Knowledge of these parameters, along with careful control of pad dimensions and placement, allows use of the metatarsal pad as an effective orthotic device for redistributing forefoot plantar pressures.

Detection of staphylococcal enterotoxin B among toxic shock syndrome (TSS)- and non-TSS-associated Staphylococcus aureus isolates

The association between staphylococcal enterotoxin (SE) B and toxic shock syndrome (TSS) toxin 1 (TSST-1) in menstrual and nonmenstrual TSS was examined. Production of SEB and TSST-1 in the culture supernatants from 344 Staphylococcus aureus isolates was quantitated by noncompetitive ELISA (lower detection limit, 0.5 ng/mL for both assays). In the ELISA for SEB, cross-reactive antibodies to SEC were removed by absorption in a biotin-streptavidin-agarose column (SEC1 at concentrations to 100,000 ng/mL could not be detected). Among TSST-1-negative isolates, SEB production in nonmenstrual TSS isolates (8/13, 62%) was more prevalent than that in either menstrual TSS isolates (1/4; P = .3), non-TSS infections (15/103, 15%; P less than .001), or asymptomatic carriers (14/105, 13%; P less than .001). Expression of SEB and TSST-1 was usually mutually exclusive (only 1.5% of 344 isolates produced both SEB and TSST-1). Multilocus enzyme electrophoretic typing (ET) suggested a clonal origin for both SEB-(55% of ET-5) and TSST-1 (76% of ET-19)-producing isolates. Thus, SEB may be an important cause in TSS where TSST-1 is not elaborated, especially in nonmenstrual TSS isolates.

Induction of tumor necrosis factor and interleukin-1 by purified staphylococcal toxic shock syndrome toxin 1 requires the presence of both monocytes and T lymphocytes

Highly purified staphylococcal toxic shock syndrome toxin 1 (TSST-1) was tested for its ability to induce the cytokines tumor necrosis factor (TNF) and interleukin-1 (IL-1) from fractionated human peripheral blood mononuclear cells prepared from seven healthy donors. Highly purified monocytes alone or T lymphocytes alone did not produce TNF or IL-1 when incubated with TSST-1 at 37 degrees C for up to 72 h. However, the addition of 10 micrograms of TSST-1 per ml to a 1:1 mixture of monocytes and T cells resulted in significant TNF (predominantly TNF-alpha) and IL-1 beta production after 24 h at 37 degrees C. The nature of the monocyte/T-cell interaction did not appear to involve gamma interferon (IFN-gamma), since 10 micrograms of rabbit anti-IFN-gamma per ml did not neutralize TNF-alpha production after TSST-1 induction. Similarly, L243, a monoclonal antibody to HLA-DR which blocks TSST-1 binding to monocytes, did not inhibit TNF-alpha production following TSST-1 induction. However, direct contact between monocytes and T cells was required, since physical separation of cells in double-chamber culture wells abolished TNF-alpha secretion after TSST-1 stimulation. Furthermore, paraformaldehyde fixation of either monocytes or T cells prior to addition to viable T cells or monocytes, respectively, also abolished TNF-alpha secretion, suggesting that aside from cell contact, soluble factors were also involved. Our results suggest that cytokine production involves more than binding of TSST-1 to its receptor on monocytes alone and that cell contact with T cells and the release of a soluble factor(s) other than IFN-gamma may be essential for the induction of cytokines by this toxin.