Impact of educational interventions on pharmacovigilance and adverse drug reaction reporting by resident doctors and faculty members: A prospective comparative study

Purpose/Aim

Adverse drug reactions (ADRs) are significantly under-reported worldwide. The aim of this study was to assess the impact of educational interventions (EIs) on knowledge, attitude, and practice (KAP) of hospital resident doctors and faculty members and compare ADR reporting in EI (medical specialties) vs. non-EI (surgical specialties) in these two cadres of doctors.

Materials and Methods

This study was a prospective comparative study conducted in two groups (EI and non-EI) in resident doctors and faculty members working at a tertiary care hospital. EI group (medical specialties) were provided with EI to increase awareness about ADR reporting, whereas in non-EI group (surgical specialties), no EI was provided and they served as control. Respondents were asked to fill a pretest questionnaire followed by interactive EI in EI group and posttest questionnaire in both groups. The impact of EI among respondents was evaluated by their response to questionnaire and number of ADRs reported after intervention.

Results

Total (n = 202) respondents were enrolled in the study. The number of resident doctors and faculty members in each group were (n = 101 [50%]). Overall, (n = 100 [49.5%]) were from the medical and (n = 102 [50.5%]) from surgical specialty. Post-EI period, there was statistically significant improvement in KAP domains.

Conclusion

Our study serves as credible evidence that through EI; statistically significant improvement in KAP of resident doctors and faculty members in both medical and surgical specialties toward ADR reporting and existing pharmacovigilance system can be achieved.

Investigating the efficacy of baricitinib in new onset type 1 diabetes mellitus (BANDIT)—study protocol for a phase 2, randomized, placebo controlled trial

Background

Type 1 diabetes (T1D) places an extraordinary burden on individuals and their families, as well as on the healthcare system. Despite recent advances in glucose sensors and insulin pump technology, only a minority of patients meet their glucose targets and face the risk of both acute and long-term complications, some of which are life-threatening.

The JAK-STAT pathway is critical for the immune-mediated pancreatic beta cell destruction in T1D. Our pre-clinical data show that inhibitors of JAK1/JAK2 prevent diabetes and reverse newly diagnosed diabetes in the T1D non-obese diabetic mouse model. The goal of this study is to determine if the JAK1/JAK2 inhibitor baricitinib impairs type 1 diabetes autoimmunity and preserves beta cell function.

Methods

This will be as a multicentre, two-arm, double-blind, placebo-controlled randomized trial in individuals aged 10–30 years with recent-onset T1D. Eighty-three participants will be randomized in a 2:1 ratio within 100 days of diagnosis to receive either baricitinib 4mg/day or placebo for 48 weeks and then monitored for a further 48 weeks after stopping study drug. The primary outcome is the plasma C-peptide 2h area under the curve following ingestion of a mixed meal. Secondary outcomes include HbA1c, insulin dose, continuous glucose profile and adverse events. Mechanistic assessments will characterize general and diabetes-specific immune responses.

Discussion

This study will determine if baricitinib slows the progressive, immune-mediated loss of beta cell function that occurs after clinical presentation of T1D. Preservation of beta cell function would be expected to improve glucose control and prevent diabetes complications, and justify additional trials of baricitinib combined with other therapies and of its use in at-risk populations to prevent T1D.

Trial registration

ANZCTR ACTRN12620000239965. Registered on 26 February 2020. ClinicalTrials.gov NCT04774224. Registered on 01 March 2021

The Clinical Case for the Integration of a Ketone Sensor as Part of a Closed Loop Insulin Pump System

Closed loop (CL) systems deliver insulin with a rapid onset and offset in action. Although favorable overall, the absence of a long-acting insulin increases the risk of diabetic ketoacidosis (DKA) which can occur with insulin delivery failure, acute illness, low carbohydrate diets, sodium glucose-linked transporter inhibitors, and high intensity exercise. A CL system relying entirely on interstitial glucose measurements may not provide an alert for DKA and many people with type 1 diabetes (T1D) do not carry a blood ketone meter and test-strips. Ketone sensing is theoretically feasible. A multianalyte platform incorporating a ketone sensor could provide an additional CL input without an increase in burden for the person with T1D, warning of impending DKA to allow remedial action to be taken. We outline the clinical case for inclusion of continuous ketone sensing as part of future CL systems.

Immunogenicity and safety of a liquid Pentavalent (DTwP-Hb-Hib) combination vaccine manufactured by Human Biologicals Institute in 6-8 weeks old healthy infants: A phase III, randomized, single blind, non-inferiority study

BACKGROUND

A liquid Pentavalent (DTwP-Hb-Hib) combination vaccine, developed by Human Biologicals Institute, underwent a Phase III clinical study in India. In this randomized, single blind, non-inferiority study, the immunogenicity and safety of this Investigational vaccine was compared with Pentavac SD® vaccine in 6-8 weeks old healthy infants.

METHODS

A total of 405 healthy infants aged 6-8 weeks old were randomized in 2:1 ratio to receive three doses of either the Investigational liquid Pentavalent (DTwP-Hb-Hib) combination vaccine or Pentavac SD® vaccine at four to six weeks interval. Immunogenicity was compared by estimation of antibody titers before the first dose and 4-6 weeks after the third dose of vaccination. Safety of each vaccine was assessed and compared by collection of data on solicited and unsolicited adverse events throughout the study period.

RESULTS

Out of a total of 405 enrolled subjects, 387 subjects completed the study. The seroconversion rates, seroprotection rates and geometric mean titres of the Investigational liquid Pentavalent (DTwP-Hb-Hib) combination vaccine group were found to be comparable and non-inferior to the Pentavac SD® vaccine group at 4-6 weeks after the third dose of vaccination. Pain, erythema and swelling at the site of injection were found to be the most common local adverse events whereas fever, irritability and unusual crying were found to be the most common systemic adverse events in both the vaccine groups. No vaccine related serious adverse event was reported. In this study, both the Investigational vaccine as well as the Comparator vaccine were found to be immunogenic and well tolerated.

CONCLUSION

After assessment of the results of the study it was concluded that the Investigational liquid Pentavalent (DTwP-Hb-Hib) combination vaccine developed by Human Biologicals Institute was immunogenic and safe when administered to infants aged 6-8 weeks and was non-inferior in immunogenicity and safety to Pentavac SD® vaccine. Clinical Trial Registry of India Identifier: CTRI/2016/01/006541.

Diabetes associated with immune checkpoint inhibition: presentation and management challenges

BACKGROUND

In recent years, immune checkpoint blockade has become a standard therapy for a wide range of cancers. Adverse events including endocrinopathies result from the induction of autoimmunity.

CASE REPORT

We report a case series of nine individuals who presented with immunotherapy-induced type 1 diabetes between 2015-2017.

DISCUSSION

Onset of diabetes occurred within 12 weeks of commencing therapy. Anti- GAD antibodies were present in six people. Retrospective testing of islet antibodies in pre-treatment samples was possible in two people and this revealed anti-GAD seroconversion in the first and high anti-GAD titres pre and post-treatment in the second person. Six people had high risk HLA haplotypes. Clinical and genetic factors are described and compared with previously published cases. This article is protected by copyright. All rights reserved.

Neurodevelopmental Outcome at 12 Months of Postnatal Magnesium Sulphate Therapy for Perinatal Asphyxia

Introduction: Postnatal magnesium therapy has been proposed as a novel neuroprotective agent for perinatal asphyxia. A few studies reported short term neurological benefit with magnesium. It is uncertain whether magnesium therapy has any long term effect on neurodevelopment.Material and Methods: We randomly assigned 120 term asphyxiated infants to receive either magnesium sulphate infusion or placebo postnatally in first 48 hours of life. Babies were treated as per the standard treatment protocol for asphyxia. Short term outcome at discharge was previously reported and a follow up evaluation at 12 months was done. The primary outcome was a composite of death or disability, developmental delay and neuromotor tone abnormality at 12 months.Results: Out of 120 infants, 69 infants had moderate-severe hypoxic-ischemic encephalopathy (HIE) during initial NICU stay. Among 69 infants with moderate-severe HIE, 41 infant could be followed up. Out of 41 infants, 22 were in magnesium group and 19 in placebo group. Of 22 infants assigned to magnesium therapy, 3(13.6%) died or survived with neurodevelopmental disability as compared with 5 of 19 infants (26.3%) assigned to placebo (p=0.32). The developmental outcome evaluated found developmental delay in 3 of 22 infants in magnesium group vs 5 of 19 infants in placebo group (p=0.32). Ameil-Tisonneuromotor tone assessment revealed tone abnormality in 3 of 22 infants in study group vs 4 of 19 infants in placebo group (p=0.53).Conclusion: Magnesium therapy for perinatal asphyxia may not result in favourable long term neurodevelopmental outcome, though no significant adverse effect has been documented.J Nepal Paediatr Soc 2016;36(3):256-262

A Japanese Encephalitis Vaccine From India Induces Durable and Cross-protective Immunity Against Temporally and Spatially Wide-ranging Global Field Strains

BACKGROUND

Japanese encephalitis (JE) is a vaccine-preventable acute disease. We report the results of a phase 2/3 trial of JENVAC, a Vero cell-derived vaccine developed using an Indian strain of JE virus (JEV).

METHODS

JENVAC was administered in 2 doses 28 days apart, and immunogenicity was compared to that from a single dose of SA-14-14-2, the only approved JE vaccine and regimen at the time in India.

RESULTS

After both the doses, seroconversion and seroprotection were >90% for JENVAC. For SA-14-14-2, seroconversion and seroprotection were 57.69% and 77.56%, respectively, on day 28 and 39.74% and 60.26%, respectively, on day 56. The geometric mean titers at day 28 and day 56 were 145.04 and 460.53, respectively, for JENVAC and 38.56 and 25.29, respectively, for SA-14-14-2. With a single dose of JENVAC, seroprotection titers lasted at least 12 months in >80% of the subjects. Following receipt of 2 doses, 61.17% of subjects retained seroprotection titers at 24 months, and immunogenicity criteria were higher than that for SA-14-14-2 at 12, 18, and 24 months each. Sera from JENVAC subjects neutralized JEV genotypes I, II, III, and IV equally well. Adverse events were not significantly different between the 2 vaccines.

CONCLUSIONS

JENVAC elicits long-lasting, broadly protective immunity.

CLINICAL TRIALS REGISTRATION

CTRI/2011/07/001855.

The National Accreditation Board for Hospital and Health Care Providers accreditation programme in India

Quality in health care is important as it is directly linked with patient safety. Quality as we know is driven either by regulation or by market demand. Regulation in most developing countries has not been effective, as there is shortage of health care providers and governments have to be flexible. In such circumstances, quality has taken a back seat. Accreditation symbolizes the framework for quality governance of a hospital and is based on optimum standards. Not only is India establishing numerous state of the art hospitals, but they are also experiencing an increase in demand for quality as well as medical tourism. India launched its own accreditation system in 2006, conforming to standards accredited by ISQua. This article shows the journey to accreditation in India and describes the problems encountered by hospitals as well as the benefits it has generated for the industry and patients.

Soft tissue reconstruction after hemimandibulectomy in oral malignancies: a retrospective study

AIMS

The present study was under taken to evaluate the efficacy of various local and regional soft tissue flaps used for reconstruction after excision of various malignant lesions of the mouth and also to evaluate complications with length of hospital stay after the reconstruction.

MATERIALS AND METHODS

The study was a record based retrospective analysis of 127 patients who were histologically proven squamous cell carcinoma of the oral cavity for which excision of the lesion along with segmental mandibulectomy and primary reconstruction with local or regional flaps was the treatment modality.

RESULTS

The male:female mean age is 48.27:48.79. The Z-proportionality test for intra oral reconstruction showed 5% level of significance (P < 0.05) between pectoralis major myocutaneous flap (PMMC) and other flaps. Difference between deltopectoral (DP) and PMMC, PMMC and primary closure at 1% level of significance, i.e. P < 0.01 was found for extra oral defects. The mean stay was found to be 31.31 days. Recurrence rate of 11% was reported.

CONCLUSION

A total of 127 patients formed the study group. In the absence of bone reconstruction PMMC still continues to be the "work horse" of reconstruction following wide excision and hemimandibulectomy.

Impact of metabolic syndrome on re-stenosis development: role of drug-eluting stents

Metabolic syndrome (MetS) is defined as a cluster of numerous cardiovascular risk factors, which encompasses obesity, dyslipidaemia, insulin resistance and hypertension. Patients with MetS are more prone to developing cardiovascular events than other patients. To date, several approaches such as physical exercise, dietary control and invasive and non-invasive therapeutic interventions for dyslipidaemia, hypertension and insulin resistance have been used to manage MetS. However, there is a progressive elevation in the incidence of fatal and non-fatal cardiovascular events due to the increased prevalence of obesity and diabetes. Percutaneous coronary intervention has emerged over the last few years as an effective revascularisation strategy for those with coronary artery disease, in parallel with the development of effective anti-platelet medications and newer drug-eluting stents. In recent years, considerable research efforts have been undertaken to elucidate the pathophysiology of re-stenosis and develop strategies to prevent re-stenosis following percutaneous transluminal coronary angioplasty and stent implantation. Although the rate of stent re-stenosis and target-lesion revascularisation has been reduced, there is little information in the literature on the outcome of MetS in the pathophysiology of re-stenosis. In this review article, we summarise the recent development and progress on re-stenosis and the role of drug-eluting stents, particularly in MetS.

Granulocyte-Colony Stimulating Factor (G-CSF) accelerates healing of radiation induced moist desquamation of the skin

DESIGN

Clinical evidence from a few experimental and randomized trials have implicated the possible benefit of cytokines in prevention and healing of radiation induced mucositis. This pilot study was undertaken to assess the effectiveness of Granulocyte-Colony Stimulating Factor (G-CSF) on healing of radiation induced moist desquamation of the skin.

RATIONALE FOR THE STUDY

intervention with exogenous growth factors along with conventional treatment practices may stimulate faster skin healing and help the patient in resuming normalcy at the earliest.

MATERIALS AND METHODS

Twenty three patients with established grade III moist desquamation of skin at the site of radiation and during the course of their radiotherapy were recruited for this study. Patients were administered a single dose of Granulocyte-Colony Stimulating Factor (G-CSF - Neupogen® (Filgrastim)) 300 µg subcutaneously at the periphery of the wound as a single session. The rate of skin healing was documented as a function of time from D1 (day of Filgastrim instillation) to the number of days required for complete healing/re-epithelization of the open skin wound.

RESULTS

There was a rapid response and decreased severity of the grade III radiation skin reactions, which extrapolated to an early resumption of radiotherapy treatment. Twenty patients (86%) showed healing of their wounds within 10 days which was notably faster than the expected 2 to 3 weeks anticipated for the severity/grade of the skin reaction. Thirteen patients (56.5%) showed a remarkably rapid response of healing within 5 days. No significant side effects were experienced after the single dose was administered. The mean duration to resolution of moist desquamation was calculated as 6.65 ± 4.73 days. Among the associated parameters, only location of lesion and depth of skin reaction significantly affected the rate of healing. Superficial epidermal erosions showed excellent response with 4.53 ± 2.07 days of re-epithelization & healing (p < 0.001) compared to deep dermal exposure. The results are suggestive of a promising role of G-CSF in the management of Grade III radiation induced skin reaction (moist desquamation).This concept requires structured randomized trials to establish significance of benefit.

CONCLUSION

G-CSF appears to promote wound healing; this cytokine has the potential to favorably modify the healing process of radiation induced moist desquamation of the skin. This study demonstrates that this dreaded side effect of radiotherapy can by managed in a very simple, convenient and cost effective way, without toxicity & intervention.

Mutations of TFAP2B in congenital heart disease patients in Mysore, South India

BACKGROUND & OBJECTIVES

Cardiac malformations in the young constitute a major portion of clinically significant birth defects. Congenital heart disease (CHD) is a common congenital cardiac birth defect, affecting nearly 1 per cent of all live births. Patent ductus arteriosus (PDA) is clinically significant foetal circulation anomaly, second most common form of CHD which constitutes approximately 10 per cent of total CHDs. The study aimed to screen for TFAP2B mutations in CHD patients of Mysore.

METHODS

With informed consent, 100 clinically diagnosed CHD patients and 50 healthy controls in Mysore, south India, were recruited for the analysis of screening of mutations. MassARRAY analysis of 5 prominent mutations of TFAP2B was performed.

RESULTS

The analysis did not show any of the five mutations of TFAP2B screened by massARRAY in patients and controls, indicating that these mutations were not involved in the manifestation of CHD in the patients at Mysore, south India.

INTERPRETATION & CONCLUSIONS

The findings suggest the lack of involvement of known mutations of TFAP2B with syndromic or nonsyndromic CHDs in Mysore patients.

Evaluation of an algorithm to guide patients with type 1 diabetes treated with continuous subcutaneous insulin infusion on how to respond to real-time continuous glucose levels: a randomized controlled trial

OBJECTIVE

To evaluate an algorithm guiding responses of continuous subcutaneous insulin infusion (CSII)-treated type 1 diabetic patients using real-time continuous glucose monitoring (RT-CGM).

RESEARCH DESIGN AND METHODS

Sixty CSII-treated type 1 diabetic participants (aged 13-70 years, including adult and adolescent subgroups, with A1C <or=9.5%) were randomized in age-, sex-, and A1C-matched pairs. Phase 1 was an open 16-week multicenter randomized controlled trial. Group A was treated with CSII/RT-CGM with the algorithm, and group B was treated with CSII/RT-CGM without the algorithm. The primary outcome was the difference in time in target (4-10 mmol/l) glucose range on 6-day masked CGM. Secondary outcomes were differences in A1C, low (<or=3.9 mmol/l) glucose CGM time, and glycemic variability. Phase 2 was the week 16-32 follow-up. Group A was returned to usual care, and group B was provided with the algorithm. Glycemia parameters were as above. Comparisons were made between baseline and 16 weeks and 32 weeks.

RESULTS

In phase 1, after withdrawals 29 of 30 subjects were left in group A and 28 of 30 subjects were left in group B. The change in target glucose time did not differ between groups. A1C fell (mean 7.9% [95% CI 7.7-8.2to 7.6% [7.2-8.0]; P < 0.03) in group A but not in group B (7.8% [7.5-8.1] to 7.7 [7.3-8.0]; NS) with no difference between groups. More subjects in group A achieved A1C <or=7% than those in group B (2 of 29 to 14 of 29 vs. 4 of 28 to 7 of 28; P = 0.015). In phase 2, one participant was lost from each group. In group A, A1C returned to baseline with RT-CGM discontinuation but did not change in group B, who continued RT-CGM with addition of the algorithm.

CONCLUSIONS

Early but not late algorithm provision to type 1 diabetic patients using CSII/RT-CGM did not increase the target glucose time but increased achievement of A1C <or=7%. Upon RT-CGM cessation, A1C returned to baseline.

Darier-Roussy Sarcoidosis Mimicking Metastatic Breast Cancer

Subcutaneous sarcoidosis (also known as ‘Darier-Roussy sarcoid’) is a cutaneous condition characterized by numerous deep-seated nodules on the trunk and extremities. Coexistence of sarcoidosis and breast cancer are reported in the literature, but there will always be a chance of misdiagnosis. It is very crucial to obtain a tissue diagnosis of suspicious metastatic lesions. We report a case of breast cancer presenting with a subcutaneous sarcoid lesion masquerading as a metastatic lesion. A 50-year-old female patient, who had had cancer of the left breast, was on hormone therapy 2 years after treatment with surgery, radiotherapy and chemotherapy. The patient presented with a sudden onset of a forehead subcutaneous swelling mimicking metastasis which on excision biopsy was proved to be sarcoidosis. In India, sarcoidosis is reported rarely. We have to keep in mind that there is a chance of the metastatic lesions being of sarcoidosis origin or another granulomatous disease. To avoid misdiagnosis, it is better to obtain a tissue diagnosis.

Essential hypertension in early and mid-adolescence

OBJECTIVES

To detect prevalence of essential hypertension in early and mid adolescents and to identify various risk factors.

METHODS

Blood pressure was recorded in 503 apparently normal school students in 10 to 16 yr age group as per standard guidelines. Detailed clinical examination was done in all cases. A detailed questionnaire was sent to parents.

RESULTS

6.16% of adolescents had high blood pressure at the end of fourth screening. Both systolic and diastolic hypertensions were documented. Increased body mass index and reduced consumption of vegetables and fruits were found to be statistically significant risk factors for hypertension.

CONCLUSION

Multiple blood pressure recordings are essential for accurate diagnosis of hypertension. There is a high prevalence of essential hypertension amongst adolescents in Mysore city with modifiable risk factors for hypertension.

Self abortion of attacks in patients with Hot Water Epilepsy

A cross sectional hospital based study was undertaken to find out the various clinical aspects and management of Hot Water Epilepsy (HWE) in children. Of the 71 cases analysed, 67.6% had onset of seizures in the first decade of life. Seizures occurred frequently towards the end of head bath (71.8%). In 14.1% cases, seizures were precipitated with cold-water head bath also. Complex partial seizures (60.6%) and generalized atonic seizures (21.1%) were common. Spontaneous non-reflex epilepsy was seen in 47.9% cases. Self-induction and self-abortion of seizures were seen in 16.9% and 12.7% patients respectively. Family history was available in 32.4% of cases. Majority had good response to continuous prophylactic treatment with antiepileptic drugs. We conclude that high incidence of spontaneous seizures and generalized atonic seizures seem to be peculiar to our geographical area. "Self abortion of attacks"may be of immense help in controlling the attacks.

Myotonia congenita--a successful response to carbamazepine

Myotonia congenita is a rare disease of skeletal muscle characterized by painless myotonia, generalized muscular hypertrophy and a non-progressive course. We report a 10-year-old girl with myotonia, "Herculean appearance" and electromyographic confirmation of myotonic discharges. There was a dramatic response to carbamazepine. The aim of this report is to make the readers aware of this entity which can be easily controlled with medication and also prevented by genetic counseling.

Transection of common bile duct following blunt injury to abdomen

Isolated complete transection of the common bile duct due to blunt abdominal trauma is rare. We report such a case following an assault.

The peri-operative use of the oesophageal Doppler monitor in patients undergoing coronary artery revascularisation. A comparison with the continuous cardiac output monitor

This study was carried out to evaluate the ease of use and reliability of cardiac output estimations performed by an oesophageal Doppler monitor and to compare its use with that of a continuous cardiac output pulmonary flotation catheter. Measurements were made during and after surgery in 16 patients scheduled to undergo coronary revascularisation. Both devices suffered significant intra-operative problems which led us to question their suitability as operating theatre monitors. After surgery the continuous cardiac output monitor provided stable results while the oesophageal Doppler monitor required the continuous presence of an experienced anaesthetist to ensure comparable cardiac output estimations.

IL-2 induces Fas ligand/Fas (CD95L/CD95) cytotoxicity in CD8+ and CD4+ T lymphocyte clones

IL-2 is a T cell growth factor that has pleiotropic functions in T cell differentiation, induction of lymphokine-activated killer cells, and regulation of immune responses. In studying TCR triggering of perforin or Fas ligand (FasL)/Fas (CD95 ligand/CD95) cytotoxicity in our influenza-specific T cell clones, we found that IL-2 can also induce FasL/Fas cytotoxicity. IL-2 induces FasL/Fas cytotoxicity in our CD8+ and CD4+ Th1 clones, but not in our CD4+ Th2 clones. IL-2 induction of cytolytic activity occurs when the CD8+ T cells are refractory to IL-2-induced proliferation. This killing is Ag independent, MHC unrestricted, and blocked by Fas.Fc fusion protein. IL-2 induces FasL/Fas cytotoxicity in a dose-dependent manner, but does not induce high levels of FasL expression as detected by flow cytometry. TCR triggered FasL/Fas cytotoxicity is detectable in CD8+ and Th1 clones by 3 h and peaks at 6 h; high levels of killing are maintained for at least 24 h. Similarly, IL-2 induces FasL/Fas killing in CD8+ and Th1 clones within 3 h of stimulation and maintains high levels for at least 24 h. TCR-triggered FasL/Fas killing is inhibited by emetine and cyclosporin A, whereas IL-2-induced FasL/Fas killing is inhibited by emetine, but not by cyclosporin A. These results demonstrate a second mechanism to induce FasL/Fas cytotoxicity in CD8+ and Th1 clones and may explain IL-2 induction of Ag-independent MHC-unrestricted lymphokine-activated killer cell activity.

IL-2 induces Fas ligand/Fas (CD95L/CD95) cytotoxicity in CD8+ and CD4+ T lymphocyte clones

IL-2 is a T cell growth factor that has pleiotropic functions in T cell differentiation, induction of lymphokine-activated killer cells, and regulation of immune responses. In studying TCR triggering of perforin or Fas ligand (FasL)/Fas (CD95 ligand/CD95) cytotoxicity in our influenza-specific T cell clones, we found that IL-2 can also induce FasL/Fas cytotoxicity. IL-2 induces FasL/Fas cytotoxicity in our CD8+ and CD4+ Th1 clones, but not in our CD4+ Th2 clones. IL-2 induction of cytolytic activity occurs when the CD8+ T cells are refractory to IL-2-induced proliferation. This killing is Ag independent, MHC unrestricted, and blocked by Fas.Fc fusion protein. IL-2 induces FasL/Fas cytotoxicity in a dose-dependent manner, but does not induce high levels of FasL expression as detected by flow cytometry. TCR triggered FasL/Fas cytotoxicity is detectable in CD8+ and Th1 clones by 3 h and peaks at 6 h; high levels of killing are maintained for at least 24 h. Similarly, IL-2 induces FasL/Fas killing in CD8+ and Th1 clones within 3 h of stimulation and maintains high levels for at least 24 h. TCR-triggered FasL/Fas killing is inhibited by emetine and cyclosporin A, whereas IL-2-induced FasL/Fas killing is inhibited by emetine, but not by cyclosporin A. These results demonstrate a second mechanism to induce FasL/Fas cytotoxicity in CD8+ and Th1 clones and may explain IL-2 induction of Ag-independent MHC-unrestricted lymphokine-activated killer cell activity.

Distinct T cell receptor signaling requirements for perforin- or FasL-mediated cytotoxicity

A diverse array of signals are generated in a cytotoxic T lymphocyte (CTL) after the T cell receptor (TCR) engages the class I major histocompatibility complex (MHC) peptide complex. These signals result in a multitude of CTL effector functions, including cellular cytotoxicity, cell surface receptor expression, and cytokine secretion. We have examined signaling through the TCR in a wild type CD8+, MHC-restricted, antigen-specific CTL clone, 14-7, and its interleukin 2-dependent variant clone 14-7FD. We report here that 14-7FD is unable to kill via the perforin mechanism of killing, yet is able to kill via the Fas ligand/Fas mechanism and secrete interferon-gamma in an antigen-specific manner. 14-7FD has cytolytic granules that contain perforin and serine esterases, which are secreted after phorbol ester and Ca2+ ionophore treatment. Lastly, to investigate which TCR signaling requirements were operational in 14-7FD, we examined TCR-triggered intracellular Ca2+ mobilization in the two clones. After TCR engagement, 14-7FD failed to mobilize intracellular Ca2+, which may be the cause for its inability to trigger the perforin/granule exocytosis mechanism of killing. These results indicate that the signal transduction events that trigger perforin killing and the signaling requirements to induce FasL expression are distinct. We hypothesize that these two distinct TCR signal transduction requirements allow for separate activation of these two mechanisms of killing relating to their role in eradication of infected cells or regulation of immune responses.