P-017 A FRAMEWORK FOR MULTIDISCIPLINARY TEAM MANAGEMENT OF ABDOMINAL WALL RECONSTRUCTION

Aim

Incisional hernias are common and can significantly impact a patient's quality of life. Traditionally, abdominal wall reconstruction (AWR) has been performed by general surgeons, or those with special interest, often working in isolation. However, there is increasing awareness of pre-optimisation, risk stratification, enhanced training, and personalising treatment using a wide range of techniques.

Methods & Results

For complex and higher-risk procedures, Multidisciplinary team (MDT) management is considered the standard of care for optimising outcomes. The lack of standardised protocols and clear evidence in AWR means that surgical management can vary greatly. This makes the MDT process even more important due to the complexity of the decision-making involved. We describe a successful MDT process for complex abdominal wall reconstruction at a tertiary referral centre. Patients are reviewed at weekly AWR meetings with a multidisciplinary team, which includes consultants, advanced clinical practitioners and trainees. This is an opportunity for objective risk stratification, radiological review and assessment of the patient's goals before preoptimization and operative planning. Prospective data is collected on all patients to allow for quality improvement and service development.

Conclusion

MDT management of abdominal wall hernia is gaining popularity but remains poorly established in most regions. The involvement of surgical colleagues and other specialists is crucial in developing this growing field of surgery. We hope to expand our team to include Radiologists and Nutritionists, with the possibility of extending to regional networks, as we continue to explore new techniques and methods in managing complex abdominal wall hernias.

P-146 A SYSTEMATIC REVIEW OF IMAGING MARKERS FOR HIATUS HERNIA OUTCOMES

Hiatus hernia repair is a common operation with considerable variation in anatomy and technique. At present there are very few predictors of post-operative outcomes. Certain imaging characteristics may help in operative planning and predicting outcomes. The aim of this systematic review is to identify possible radiological markers associated with clinical outcomes in hiatal hernia repair.

A literature search was performed on the 7th December 2021 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-analysis Of Observational Studies in Epidemiology guidelines of the PubMed, EMBASE and Cochrane Central Register of Controlled Trials using the following search term: ((hiatus) OR (paraesophageal)) AND (hernia) AND ((computed tomography) OR (CT) OR (imaging) OR (contrast) OR (swallow) OR (magnetic resonance) OR (ultrasound)). Inclusion criteria were studies (any design) testing the association of a radiological marker with any clinical outcome (either operative or non-operative) of hiatus hernia management. Exclusion criteria were case reports, non-English articles, non-human articles. Articles were screened by 2/3 authors on the basis of title and abstract. Full text articles were then retrieved for detailed analysis. Any disagreement was resolved by consultation with a 3rd/4th author.

Initial search identified 2768 papers, 9 of which were retrieved for full paper evaluation.

Preliminary review of the literature suggests that hernia recurrence is correlated with increased hernia size, although patients tend to be asymptomatic. Multidimensional CT can accurately measure hernia surface area and this could be useful in stratifying risk of re-herniation.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Transcranial Doppler Velocities and Angiographic Vasospasm after SAH: A Diagnostic Accuracy Study

BACKGROUND AND PURPOSE

After aneurysmal SAH, transcranial Doppler is commonly used to monitor cerebral vasospasm. The diagnostic accuracy of transcranial Doppler flow velocity values in detecting angiographic vasospasm in patients requiring urgent endovascular intervention has not been established.

MATERIALS AND METHODS

We performed a retrospective analysis of a consecutive series of patients with aneurysmal SAH who underwent transcranial Doppler (index test) within 24 hours of conventional angiography (reference test). The judgment of 33%, 50%, and 66% degree of vessel narrowing on angiography was independently established by multiple neuroendovascular clinicians. Vessel-specific per-segment and per-patient transcranial Doppler velocities were studied using receiver operating characteristic curves, the Youden index, and minimal acceptable sensitivity models. Optimal mean flow-velocity thresholds were explored to calculate sensitivity and specificity using a per-patient judgment of vasospasm of at least 50% angiographic narrowing in any large arterial segment except A1.

RESULTS

In 221 patients, vasospasm was found in 15%, 8%, and 4% of arteries when the degree of reference angiographic luminal narrowing was 33%, 50%, and 66%, respectively. Mean flow velocities were significantly higher in vasospastic segments (P = . 001), but per-segment exploratory analyses yielded unsound mean flow velocity thresholds. The Youden and minimal acceptable sensitivity models proposed mean flow velocity thresholds of approximately 160 cm/s for the anterior circulation and 80 cm/s for the posterior circulation in the per-patient diagnosis of angiographic vasospasm (≥50%), yielding a sensitivity of 80%-90% (95% CI, 0.77-0.96), but with a corresponding specificity of 50% (95% CI, 0.40-0.56).

CONCLUSIONS

In this study, a threshold transcranial Doppler mean flow-velocity value that would accurately diagnose ≥50% angiographic vasospasm remained elusive.

Patient-reported outcomes after oesophagectomy in the multicentre LASER study

BACKGROUND

Data on the long-term symptom burden in patients surviving oesophageal cancer surgery are scarce. The aim of this study was to identify the most prevalent symptoms and their interactions with health-related quality of life.

METHODS

This was a cross-sectional cohort study of patients who underwent oesophageal cancer surgery in 20 European centres between 2010 and 2016. Patients had to be disease-free for at least 1 year. They were asked to complete a 28-symptom questionnaire at a single time point, at least 1 year after surgery. Principal component analysis was used to assess for clustering and association of symptoms. Risk factors associated with the development of severe symptoms were identified by multivariable logistic regression models.

RESULTS

Of 1081 invited patients, 876 (81.0 per cent) responded. Symptoms in the preceding 6 months associated with previous surgery were experienced by 586 patients (66.9 per cent). The most common severe symptoms included reduced energy or activity tolerance (30.7 per cent), feeling of early fullness after eating (30.0 per cent), tiredness (28.7 per cent), and heartburn/acid or bile regurgitation (19.6 per cent). Clustering analysis showed that symptoms clustered into six domains: lethargy, musculoskeletal pain, dumping, lower gastrointestinal symptoms, regurgitation/reflux, and swallowing/conduit problems; the latter two were the most closely associated. Surgical approach, neoadjuvant therapy, patient age, and sex were factors associated with severe symptoms.

CONCLUSION

A long-term symptom burden is common after oesophageal cancer surgery.

FBXW7 regulates DISC1 stability via the ubiquitin-proteosome system

Disrupted in schizophrenia 1 (DISC1) is a multi-functional scaffolding protein that has been associated with neuropsychiatric disease. The role of DISC1 is to assemble protein complexes that promote neural development and signaling, hence tight control of the concentration of cellular DISC1 in neurons is vital to brain function. Using structural and biochemical techniques, we show for we believe the first time that not only is DISC1 turnover elicited by the ubiquitin proteasome system (UPS) but that it is orchestrated by the F-Box protein, FBXW7. We present the structure of FBXW7 bound to the DISC1 phosphodegron motif and exploit this information to prove that disruption of the FBXW7-DISC1 complex results in a stabilization of DISC1. This action can counteract DISC1 deficiencies observed in neural progenitor cells derived from induced pluripotent stem cells from schizophrenia patients with a DISC1 frameshift mutation. Thus manipulation of DISC1 levels via the UPS may provide a novel method to explore DISC1 function.

Liver transplantation outcome in patients with angiographically proven coronary artery disease: a multi-institutional study

Over the last decade the age of liver transplant (LT) recipients and the likelihood of coronary artery disease (CAD) in this population have increased. There are no multicenter studies that have examined the impact of CAD on LT outcomes. In this historical cohort study, we identified adult LT recipients who underwent angiography prior to transplantation at seven institutions over a 12-year period. For each patient we recorded demographic data, recipient and donor risk factors, duration of follow-up, the presence of angiographically proven obstructive CAD (≥50% stenosis) and post-LT survival. Obstructive CAD was present in 151 of 630 patients, the CAD(+) group. Nonobstructive CAD was found in 479 patients, the CAD(-) group. Patient survival was similar for the CAD(+) group (adjusted HR 1.13, CI = [0.79, 1.62], p = 0.493) compared to the CAD(-) group. The CAD(+) patients were further stratified into severe (CADsev, >70% stenosis, n = 96), and moderate CAD (CADmod, 50-70% stenosis, n = 55) groups. Survival for the CADsev (adjusted HR = 1.26, CI = [0.83, 1.91], p = 0.277) and CADmod (adjusted HR = 0.93, CI = [0.52, 1.66], p = 0.797) groups were similar to the CAD(-) group. We conclude that when current CAD treatment strategies are employed prior to transplant, post-LT survival is not significantly different between patients with and without obstructive CAD.

Effect of frameshift mutagen acriflavine on control of resistance genes in Acinetobacter baumannii

Acinetobacter baumannii is a Gram-negative pathogenic bacterium that often exhibits a multidrug-resistant phenotype causing infections at various sites of the body and increasingly leading to septicaemic shock. This study evaluated the role of acriflavine, a frameshift mutagen, on the movement of insertion sequence ISAba1 in clinical isolates of A. baumannii, with the focus on changes in expression levels of the bla(ADC) and bla(OXA-51-like) genes. Resistance profiles were assessed with consideration of ISAba1 acting as a promoter upstream of the bla(ADC) or bla(OXA-51-like) gene. ISAba1 movement was observed in the acriflavine mutants Ab153M and Ab1225M. Ab153M exhibited an increase in the MIC values of carbapenems and ceftazidime, with ISAba1 gained upstream of the bla(ADC) and bla(OXA-51-like) genes, correlating with an increase in gene expression. Reduced expression of the 17, 23 and 25 kDa outer-membrane proteins (OMPs) was also observed in Ab153M. There was a significant decrease in MIC values of carbapenems with the loss of ISAba1 upstream of the bla(ADC) and bla(OXA-51-like) genes in strain Ab1225M, and a significant decrease in bla(OXA-51-like) gene expression and, to a lesser extent, in bla(ADC) expression. Ab1225M and a serially subcultured Ab1225 strain (Ab1225s) exhibited overexpression of the 17, 23, 25 and 27 kDa OMPs. There was a decrease in MIC values of the carbapenems and piperacillin/tazobactam but not of ceftazidime in Ab1225s, which had ISAba1 upstream of the bla(ADC) and bla(OXA-51-like) genes. A significant decrease in bla(OXA-51-like) expression was observed in Ab1225s, whereas the expression of bla(ADC) was similar to that in the Ab1225 parental strain. The attenuation in this strain may be due to overexpression of OMPs and it is clear that, even if ISAba1 is present upstream of an antibiotic resistance gene, it may not necessarily contribute towards the overexpression of antibiotic resistance genes (bla(OXA-51-like) in Ab1225s). Movement of the IS element within the A. baumannii chromosome may be an important regulatory mechanism employed by the bacterium under particular stress conditions, and the ability to upregulate the expression of antibiotic resistance genes is likely to be an important factor in the pathogenicity of this bacterium.

Compliance with routine antenatal rhesus D prophylaxis and the impact on sensitisations: observations over 14 years

Documented routine antenatal anti-D prophylaxis was given to 90% and 81-87% of eligible women at 28 and 34 weeks of gestation, respectively, during the early 1990s and early 2000s. With increasing experience and education, a significant improvement in the timing of the first (OR 0.26, 95% CI 0.16-0.41: P < 0.0001) and second injections (OR 0.40, 95% CI 0.26-0.61: P < 0.0001) occurred during the latter period. Despite these improvements, there was no reduction in the sensitisation rate at 0.4%. However, this low rate occurred despite significant proportions of women delivering more than 42 days after the second injection. Fifteen of the 16 sensitised women had received routine antenatal prophylaxis.

Synthesis, binding studies and in vivo biological evaluation of novel non-peptide antihypertensive analogues

AT(1) antagonists (SARTANs) constitute the last generation of drugs for the treatment of hypertension, designed and synthesized to mimic the C-terminal segment of the vasoconstrictive hormone angiotensin II (AngII). They exert their action by blocking the binding of AngII on the AT(1) receptor. Up to date eight AT(1) antagonists have been approved for the regulation of high blood pressure. Although these molecules share common structural features and are designed to act under the same mechanism, they have differences in their pharmacological profiles and antihypertensive efficacy. Thus, there is still a need for novel analogues with better pharmacological and financial profiles. An example of a novel synthetic non peptide AT(1) antagonist which devoids the classical template of SARTANs is MM1. In vivo studies showed that MMK molecules, which fall in the same class of MM1, had a significant antihypertensive (40-80% compared to the drug losartan) activity. However, in vitro affinity studies showed that losartan has considerably higher affinity. The theoretical docking studies showed that MM1 acts on the same site of the receptor as losartan. They exert hydrophobic interactions with amino acid Val108 of the third helix of the AT(1) receptor and other hydrophobic amino acids in spatial vicinity. In addition, losartan favours multiple hydrogen bondings between its tetrazole group with Lys199. These additional interactions may in part explain its higher in vitro binding affinity.

N-Alkyl-N-arylmethylpiperidin-4-amines: Novel dual inhibitors of serotonin and norepinephrine reuptake

A series of N-alkyl-N-arylmethylpiperidin-4-amines have been prepared and are demonstrated to be inhibitors of both serotonin and norepinephrine reuptake.

Benzothienyloxy phenylpropanamines, novel dual inhibitors of serotonin and norepinephrine reuptake

A series of benzothienyloxy propylamines have been prepared and are demonstrated to be inhibitors of both serotonin and norepinephrine reuptake.

014.Novel uterine genes in regulation of embryo implantation

Implantation of the embryo into the maternal endometrium is the first and critical step leading to the establishment of a pregnancy. It has been well established that only during the 'window' of implantation, a limited time span when the uterine environment is receptive, can a blastocyst successfully implant into the uterus. The development of uterine receptivity is accompanied by remarkable morphological and physiological changes in the endometrium, and this is primarily driven by the coordinated effects of the ovarian steroid hormones. Uterine tissue remodelling during implantation also contributes significantly to the development of the placenta. Insufficient uterine remodelling causes implantation failure and infertility. To date, the exact molecular events occurring in the uterus during the establishment of receptivity and at the actual site of implantation are still not well understood. We used the mouse as a model and identified a number of previously unrecognised molecules that are uniquely regulated in the early stages of implantation: one of these is proprotein convertase 6 (PC6). The potential importance of these genes and their products in modulating fertility in the primate, including the human, was demonstrated by their unique spatial and temporal expression in the endometrium of human and rhesus monkey during the phase of uterine receptivity and at implantation. The importance of the genes for implantation was ultimately confirmed by functional studies in vivo using morpholino antisense oligonucleotides. These molecules will be discussed in terms of their identity, expression and functions.

Duloxetine (Cymbalta™), a dual inhibitor of serotonin and norepinephrine reuptake

A series of naphthalenyloxy-arylpropylamines have been prepared and are demonstrated to be inhibitors of both serotonin and norepinephrine reuptake. One member of this series, duloxetine (Cymbalta) has proven to be effective in clinical trials for the treatment of depression.

A new system for sternal intraosseous infusion in adults

BACKGROUND

Intraosseous (IO) infusion provides an alternative route for the administration of fluids and medications when difficulty with peripheral or central lines is encountered during resuscitation of critically ill and injured patients.

OBJECTIVE

To report the first 50 uses of a new system for emergency IO infusion into the sternum in adults, the Pyng F.A.S.T.1 IO infusion system.

METHODS

Six emergency departments and five prehospital emergency medical services (EMS) sites in Canada and the United States provided clinical and/or research data on their use of the IO system in a pilot study of success rates, insertion times, and complications. Indications for use included adult patient, urgent need for fluids or medications, and unacceptable delay or inability to achieve standard vascular access. A basic data set was standardized for all sites, and some sites collected additional data.

RESULTS

The overall success rate for achieving vascular access with the system was 84%. Success rates were 74% for first-time users, and 95% for experienced users. Failure to achieve vascular access occurred most frequently in patients (5 of 9) described subjectively by the user as "very obese," in whom there was a thick layer of tissue overlying the sternum. Mean time to achieve vascular access was 77 seconds. Flow rates of up to 80 mL/min were reported for gravity drip, and more than 150 mL/min by syringe bolus. Pressure cuffs were also used successfully, although fluid rate was controlled by clamping the line. Further research on flow rates is needed. No complications or complaints were reported at two-month follow-up.

CONCLUSION

These early data indicate that sternal IO infusion using the new F.A.S.T.1 IO system may provide rapid, safe vascular access and may be a useful technique for reducing unacceptable delays in the provision of emergency treatment.

Specific destruction of kinetochore protein CENP-C and disruption of cell division by herpes simplex virus immediate-early protein Vmw110

Examination of cells at the early stages of herpes simplex virus type 1 infection revealed that the viral immediate-early protein Vmw110 (also known as ICP0) formed discrete punctate accumulations associated with centromeres in both mitotic and interphase cells. The RING finger domain of Vmw110 (but not the C-terminal region) was essential for its localization at centromeres, thus distinguishing the Vmw110 sequences required for centromere association from those required for its localization at other discrete nuclear structures known as ND10, promyelocytic leukaemia (PML) bodies or PODs. We have shown recently that Vmw110 can induce the proteasome-dependent loss of several cellular proteins, including a number of probable SUMO-1-conjugated isoforms of PML, and this results in the disruption of ND10. In this study, we found some striking similarities between the interactions of Vmw110 with ND10 and centromeres. Specifically, centromeric protein CENP-C was lost from centromeres during virus infection in a Vmw110- and proteasome-dependent manner, causing substantial ultrastructural changes in the kinetochore. In consequence, dividing cells either became stalled in mitosis or underwent an unusual cytokinesis resulting in daughter cells with many micronuclei. These results emphasize the importance of CENP-C for mitotic progression and suggest that Vmw110 may be interfering with biochemical mechanisms which are relevant to both centromeres and ND10.

Active vision: visual activity in everyday life

Recent studies that consider how vision is used in everyday life have led to a new perspective in visual science, in which more emphasis is placed on the active role of the viewer.

Immunoelectron microscopic localisation of the OMP90 family on the outer membrane surface of Chlamydia psittaci

The putative outer membrane location of the OMP90 (formerly POMP) family from the ovine abortion strain of Chlamydia psittaci was investigated by immunoelectron microscopy. Using a non-embedding technique, antigens were shown to be localised on the outer membrane surface of both elementary and reticulate bodies, the infectious and non-infectious forms of Chlamydiae respectively. Antibodies affinity-purified against the expressed amino- and carboxy-terminal halves of one of the family members. OMP90A, demonstrated that the amino half is surface-exposed while the carboxyl half is most probably localised internally. Surface localisation on elementary bodies indicates the importance of these proteins as protective antigen candidates.

Three-dimensional modelling of G protein-linked receptors

Members of the G protein-linked receptor superfamily have not yet yielded to X-ray crystallography. However, diffraction data from other membrane-bound receptors - the photosynthetic reaction centre and bacteriorhodopsin - have provided some information that may also apply to the G protein family. John Findlay and Elias Eliopoulos integrate this information together with analysis of amino acid sequences from cloned receptors, to derive workable three-dimensional models of these proteins. Such models identify ligand-binding and G protein-associating domains.

Long term survival after intensive care

OBJECTIVE

To examine the long term survival of critically ill patients admitted to an intensive therapy unit and to ascertain the effects of age, severity of illness, and diagnostic category at admission on survival.

DESIGN

Retrospective observational study with prospectively gathered data on all patients admitted to the unit between June 1985 and July 1987 and followed up until 1 January 1989.

SETTING

Regional intensive therapy unit.

PATIENTS

513 critically ill adult patients, 16 of whom were excluded because measurements on severity of illness scoring were not available.

MAIN OUTCOME MEASURES

Age, severity of illness (determined with the acute physiology and chronic health evaluation (APACHE) II score), and diagnostic category on admission; deaths in the unit; and long term survival after discharge. Details of the survivors were sent to the Registrar General for Scotland, who issued copies of death certificates for the patients who had died between discharge and 1 January 1989.

RESULTS

Of 497 patients, 119 (24%) died in the intensive therapy unit and 120 (24%) after discharge, leaving 258 (52%) who were still alive at two years. The median (APACHE II) score was 13 and about half of the patients were aged 55 years or more. A wide range of critical illnesses, except neurosurgical emergencies, were treated. Survival analysis showed that only 41 (34%) of 122 patients with an APACHE II score of greater than or equal to 20 were alive at one year (95% confidence interval 25 to 42) compared with 124 (80%) of 155 patients with a score of less than 10 (73 to 87). Of the 144 patients aged 65 or more, only 68 (47%) survived to one year (39 to 55) but 90 (83%) of the 109 patients aged between 18 and 34 survived a similar period (76 to 71). Mortality was also related to diagnostic category; 71% of trauma victims survived to one year compared with only 41% of those admitted with gastrointestinal pathology. Univariate analysis of the results showed that age, severity of illness, and diagnosis were all predictors of long term survival. Multivariate analysis, however, showed that only age and severity of illness were independent prognostic factors.

CONCLUSIONS

Long term survival of patients treated in an intensive therapy unit is related to severity of illness and to age. The outcome from critical illness in the elderly population is poor.

Survival associated with renovascular disease in Glasgow and Newcastle: a collaborative study

Data from 121 consecutive patients with hypertension and renovascular disease, first diagnosed between 1975 and 1982 in Glasgow and Newcastle, were analysed retrospectively to determine the factors which influenced their outcome. Thirty-six patients died between the data of arteriography and 1st January 1987, giving five and ten year survival rates of 83% and 67%. Survival was greatly reduced in comparison with that of age-sex-matched controls in the general population of the West of Scotland, and was also less than that of essential hypertensives matched for age, sex, initial diastolic blood pressure and smoking habit who had attended the Glasgow Blood Pressure Clinic during the same period. Multivariate analysis showed that age, cigarette smoking and presence of atheromatous disease were significantly and independently related to outcome among the patients with renovascular disease, whereas male sex, centre of origin, severity of hypertension when first seen, initial renal function and presence of bilateral disease were not. Despite a trend towards benefit from surgical intervention (ten year survival in medical group 62%, in surgical group 71%; p = 0.19) our data do not prove that intervention is better than medical treatment, largely because the decision on intervention was not randomised. A prospective trial would be required to answer this important question.

Interleukin-6 enhances the induction of human lymphokine-activated killer cells

Human peripheral blood mononuclear cells develop a powerful lytic capacity when cultured in vitro with interleukin-2 (IL-2), becoming lymphokine-activated killer cells (LAK cells). As part of an investigation into means of influencing this process, the effect of other cytokines has been examined. In this study we describe the ability of interleukin-6 (IL-6) to regulate the induction and function of human LAK cells. The results show that substitution of IL-6 for IL-2 did not lead to the development of functional LAK cells, nor was IL-6 able to alter the lytic capacity of established LAK cells. However, when IL-6 was included with IL-2 during the induction phase of the LAK cells, the resulting cells displayed considerably greater lytic activity than those prepared with IL-2 alone. This effect was IL-6 dose-related. These results indicate that LAK cell development may be positively regulated in vitro; the implications of this observation for the clinical usage of LAK cells are discussed.