Targeting enhancer switching overcomes non-genetic drug resistance in acute myeloid leukaemia

Non-genetic drug resistance is increasingly recognised in various cancers. Molecular insights into this process are lacking and it is unknown whether stable non-genetic resistance can be overcome. Using single cell RNA-sequencing of paired drug naïve and resistant AML patient samples and cellular barcoding in a unique mouse model of non-genetic resistance, here we demonstrate that transcriptional plasticity drives stable epigenetic resistance. With a CRISPR-Cas9 screen we identify regulators of enhancer function as important modulators of the resistant cell state. We show that inhibition of Lsd1 (Kdm1a) is able to overcome stable epigenetic resistance by facilitating the binding of the pioneer factor, Pu.1 and cofactor, Irf8, to nucleate new enhancers that regulate the expression of key survival genes. This enhancer switching results in the re-distribution of transcriptional co-activators, including Brd4, and provides the opportunity to disable their activity and overcome epigenetic resistance. Together these findings highlight key principles to help counteract non-genetic drug resistance.

Click chemistry enables preclinical evaluation of targeted epigenetic therapies

The success of new therapies hinges on our ability to understand their molecular and cellular mechanisms of action. We modified BET bromodomain inhibitors, an epigenetic-based therapy, to create functionally conserved compounds that are amenable to click chemistry and can be used as molecular probes in vitro and in vivo. We used click proteomics and click sequencing to explore the gene regulatory function of BRD4 (bromodomain containing protein 4) and the transcriptional changes induced by BET inhibitors. In our studies of mouse models of acute leukemia, we used high-resolution microscopy and flow cytometry to highlight the heterogeneity of drug activity within tumor cells located in different tissue compartments. We also demonstrate the differential distribution and effects of BET inhibitors in normal and malignant cells in vivo. This study provides a potential framework for the preclinical assessment of a wide range of drugs.

Intraoperative pelvic brachytherapy for treatment of locally advanced or recurrent colorectal cancer

BACKGROUND

The aim of this study was to evaluate the efficacy and morbidity of intraoperative radiation therapy (IORT) for advanced colorectal cancer.

METHODS

All patients undergoing IORT for locally advanced rectal cancer from 2001-2009 were reviewed for cancer recurrence, survival, and procedure-related morbidity. Cumulative event rates were estimated using the method of Kaplan and Meier.

RESULTS

Twenty-nine patients with locally advanced (n = 8) or recurrent (n = 21) rectal cancers were treated with IORT and resection. Surgical interventions included low anterior resection, abdominoperineal resection, pelvic exenteration, and a variety of non-anatomic resections of pelvic recurrences. R(0) resections were achieved in 16 patients, while R(1) resections were achieved in 10, and margins were grossly positive in 3 patients. IORT was delivered to all patients over a median area of 48 (42-72) cm(2) at a median dose of 12 (12-15) Gy. Local and overall recurrence rates were 24 % (locally advanced group) and 45 % (recurrent group). Median disease-free and overall survival were 25 and 40 months respectively at a median follow-up of 26 (18-42) months. The short-term (≤30 days) complication rate was 45 %. Eight patients developed local wound complications, 5 of which required operative intervention. Four patients developed intra-abdominal abscesses requiring drainage. Long-term (>30 days) complications were identified in 11 patients (38 %) and included long-term wound complications (n = 3), ureteral obstruction requiring stenting (n = 1), neurogenic bladder (n = 3), enteric fistulae (n = 2), small bowel obstruction (n = 1), and neuropathic pain (n = 1).

CONCLUSIONS

Intraoperative brachytherapy is a viable IORT option during pelvic surgery for locally advanced or recurrent colorectal cancer but is associated with high postoperative morbidity. Whether intraoperative brachytherapy can improve local recurrence rates for locally advanced or recurrent colorectal cancer will require further prospective investigation.

A phase I multi-institutional study of systemic sorafenib in conjunction with regional melphalan for in-transit melanoma of the extremity

BACKGROUND

Isolated limb infusion with melphalan (ILI-M) corrected for ideal body weight (IBW) is a well-tolerated treatment for patients with in-transit extremity melanoma with an approximate 29 % complete response (CR) rate. Sorafenib, a multi-kinase inhibitor, has been shown to augment tumor response to chemotherapy in preclinical studies.

METHODS

A multi-institutional, dose-escalation, phase I study was performed to evaluate the safety and antitumor activity of sorafenib in combination with ILI-M. Patients with AJCC stage IIIB/IIIC/IV melanoma were treated with sorafenib starting at 400 mg daily for 7 days before and 7 days after ILI-M corrected for IBW. Toxicity, drug pharmacokinetics, and tumor protein expression changes were measured and correlated with clinical response at 3 months.

RESULTS

A total of 20 patients were enrolled at two institutions. The maximum tolerated dose (MTD) of sorafenib in combination with ILI-M was 400 mg. Four dose-limiting toxicities occurred, including soft tissue ulcerations and compartment syndrome. There were three CRs (15 %) and four partial responses (20 %). Of patients with the Braf mutation, 83 % (n = 6) progressed compared with only 33 % without (n = 12). Short-term sorafenib treatment did alter protein expression as measured with reverse phase protein array (RPPA) analysis, but did not inhibit protein expression in the MAP kinase pathway. Sorafenib did not alter melphalan pharmacokinetics.

CONCLUSION

This trial defined the MTD of systemically administered sorafenib in combination with ILI-M. Although some responses were seen, the addition of sorafenib to ILI-M did not appear to augment the effects of melphalan but did increase regional toxicity.

Ral activation promotes melanomagenesis

Up to one-third of human melanomas are characterized by an oncogenic mutation in the gene encoding the small guanosine triphosphatase (GTPase) NRAS. Ras proteins activate three primary classes of effectors, namely, Rafs, phosphatidyl-inositol-3-kinases (PI3Ks) and Ral guanine exchange factors (RalGEFs). In melanomas lacking NRAS mutations, the first two effectors can still be activated through an oncogenic BRAF mutation coupled with a loss of the PI3K negative regulator PTEN. This suggests that Ras effectors promote melanoma, regardless of whether they are activated by oncogenic NRas. The only major Ras effector pathway not explored for its role in melanoma is the RalGEF-Ral pathway, in which Ras activation of RalGEFs converts the small GTPases RalA and RalB to an active guanosine triphosphate-bound state. We report that RalA is activated in several human melanoma cancer cell lines harboring an oncogenic NRAS allele, an oncogenic BRAF allele or wild-type NRAS and BRAF alleles. Furthermore, short hairpin RNA (shRNA)-mediated knockdown of RalA, and to a lesser extent of RalB, variably inhibited the tumorigenic growth of melanoma cell lines having these three genotypes. Thus, as is the case for Raf and PI3 K signaling, Rals also contribute to melanoma tumorigenesis.

Complications of pancreaticoduodenectomy after neoadjuvant chemoradiation in patients with and without preoperative biliary drainage

BACKGROUND

It has been suggested that preoperative biliary drainage increases the risk of infectious complications of pancreaticoduodenectomy.

AIMS

The aim of this study was to assess complications related to biliary stents/drains and postoperative morbidity in patients undergoing neoadjuvant chemoradiotherapy for periampullary cancer.

PATIENTS

One hundred and eighty-four patients with periampullary neoplasms were prospectively selected for neoadjuvant external beam radiation therapy and 5-fluorouracil-based chemotherapy between 1995 and 2002.

METHODS

The data were retrospectively completed and analysed with respect to biliary drainage, efficacy and complications of endoscopic biliary stents and postoperative morbidity. Patients who had undergone a surgical biliary bypass were excluded.

RESULTS

Data were completed in 168 patients. One hundred and nineteen patients were treated with endoscopic biliary stents, 18 patients had a percutaneous biliary drain and 31 patients did not require biliary drainage. Hospitalisation for stent-related complications was necessary in 15% of the patients with endoscopic biliary stents. Seventy-two patients underwent pancreaticoduodenectomy. There was no significant difference in the rate of wound infections, intra-abdominal abscesses and overall complications between the groups with and without preoperative biliary drainage.

CONCLUSIONS

Postoperative infectious complications are common in patients both with and without preoperative biliary drainage. A statistically significant difference in complication rates was not observed between these groups.

Complications of pancreaticoduodenectomy after neoadjuvant chemoradiation in patients with and without preoperative biliary drainage

BACKGROUND

It has been suggested that preoperative biliary drainage increases the risk of infectious complications of pancreaticoduodenectomy.

AIMS

The aim of this study was to assess complications related to biliary stents/drains and postoperative morbidity in patients undergoing neoadjuvant chemoradiotherapy for periampullary cancer.

PATIENTS

One hundred and eighty-four patients with periampullary neoplasms were prospectively selected for neoadjuvant external beam radiation therapy and 5-fluorouracil-based chemotherapy between 1995 and 2002.

METHODS

The data were retrospectively completed and analysed with respect to biliary drainage, efficacy and complications of endoscopic biliary stents and postoperative morbidity. Patients who had undergone a surgical biliary bypass were excluded.

RESULTS

Data were completed in 168 patients. One hundred and nineteen patients were treated with endoscopic biliary stents, 18 patients had a percutaneous biliary drain and 31 patients did not require biliary drainage. Hospitalisation for stent-related complications was necessary in 15% of the patients with endoscopic biliary stents. Seventy-two patients underwent pancreaticoduodenectomy. There was no significant difference in the rate of wound infections, intra-abdominal abscesses and overall complications between the groups with and without preoperative biliary drainage.

CONCLUSIONS

Postoperative infectious complications are common in patients both with and without preoperative biliary drainage. A statistically significant difference in complication rates was not observed between these groups.

Neoadjuvant chemoradiation for localized adenocarcinoma of the pancreas

BACKGROUND

The use of neoadjuvant (preoperative) chemoradiotherapy (CRT) for pancreatic cancer has been advocated for its potential ability to optimize patient selection for surgical resection and to downstage locally advanced tumors. This article reports our experience with neoadjuvant CRT for localized pancreatic cancer.

METHODS

Since 1995, 111 patients with radiographically localized, pathologically confirmed pancreatic adenocarcinoma have received neoadjuvant external beam radiation therapy (EBRT; median, 4500 cGy) with 5-flourouracil-based chemotherapy. Tumors were defined as potentially resectable (PR, n = 53) in the absence of arterial involvement and venous occlusion and locally advanced (LA, n = 58) with arterial involvement or venous occlusion by CT.

RESULTS

Five patients (4.5%) were not restaged due to death (n = 3) or intolerance of therapy (n = 2). Twenty-one patients (19%) manifested distant metastatic disease on restaging CT. Twenty-eight patients with initially PR tumors (53%) and 11 patients with initially LA tumors (19%) were resected after CRT. Histologic examination revealed significant fibrosis in all resected specimens and two complete responses. Surgical margins were negative in 72%, and lymph nodes were negative in 70% of resected patients. Median survival in resected patients has not been reached at a median follow-up of 16 months.

CONCLUSIONS

Neoadjuvant CRT provided an opportunity for patients with occult metastatic disease to avoid the morbidity of resection and resulted in tumor downstaging in a minority of patients with LA tumors. Survival after neoadjuvant CRT and resection appears to be at least comparable to survival after resection and adjuvant (postoperative) CRT.

Complete response to neoadjuvant chemoradiation for rectal cancer does not influence survival

BACKGROUND

Up to 30% of patients with locally advanced rectal cancer have a complete clinical or pathologic response to neoadjuvant chemoradiation. This study analyzes complete clinical and pathologic responders among a large group of rectal cancer patients treated with neoadjuvant chemoradiation.

METHODS

From 1987 to 2000, 141 consecutive patients with biopsy-proven, locally advanced rectal cancer were treated with preoperative 5-fluorouracil-based chemotherapy and radiation. Clinical restaging after treatment consisted of proctoscopic examination and often computed tomography scan. One hundred forty patients then underwent operative resection, with results tracked in a database. Standard statistical methods were used to examine the outcomes of those patients with complete clinical or pathologic responses.

RESULTS

No demographic differences were detected between either clinical complete and clinical partial responders or pathologic complete and pathologic partial responders. The positive predictive value of clinical restaging was 60%, and accuracy was 82%. By use of the Kaplan-Meier life table analysis, clinical complete responders had no advantage in local recurrence, disease-free survival, or overall survival rates when compared with clinical partial responders. Pathologic complete responders also had no recurrence or survival advantage when compared with pathologic partial responders. Of the 34 pathologic T0 tumors, 4 (13%) had lymph node metastases.

CONCLUSIONS

Clinical assessment of complete response to neoadjuvant chemoradiation is unreliable. Micrometastatic disease persists in a proportion of patients despite pathologic complete response. Observation or local excision for patients thought to be complete responders should be undertaken with caution.

Staging of pancreatic cancer before and after neoadjuvant chemoradiation

Neoadjuvant chemoradiation therapy is used at many institutions for treatment of localized adenocarcinoma of the pancreas. Accurate staging before neoadjuvant therapy identifies patients with distant metastatic disease, and restaging after neoadjuvant therapy selects patients for laparotomy and attempted resection. The aims of this study were to (1) determine the utility of staging laparoscopy in candidates for neoadjuvant therapy and (2) evaluate the accuracy of restaging CT following chemoradiation. Staging laparoscopy was performed in 98 patients with radiographically potentially resectable (no evidence of arterial abutment or venous occlusion) or locally advanced (arterial abutment or venous occlusion) adenocarcinoma of the pancreas. Unsuspected distant metastasis was identified in 8 (18%) of 45 patients with potentially resectable tumors and 13 (24%) of 55 patients with locally advanced tumors by CT. Neoadjuvant chemoradiation therapy and restaging CT were completed in a total of 103 patients. Thirty-three patients with potentially resectable tumors by restaging CT underwent surgical exploration and resections were performed in 27 (82%). Eleven (22%) of 49 patients with locally advanced tumors by restaging CT were resected, with negative margins in 55%; the tumors in these 11 patients had been considered locally advanced because of arterial involvement on restaging CT. Staging laparoscopy is useful for the exclusion of patients with unsuspected metastatic disease from aggressive neoadjuvant chemoradiation protocols. Following neoadjuvant chemoradiation, restaging CT guides the selection of patients for laparotomy but may overestimate unresectability to a greater extent than does prechemoradiation CT.

Validation of delayed sentinel lymph node mapping for melanoma

PURPOSE

Sentinel lymph node mapping using radiolabeled tracer and blue dye is widely accepted and applied for staging melanoma. Common practice involves injection of radiolabeled tracer on the morning of surgery. However, optimal timing of radiolabeled colloid injection with respect to surgery remains debated. Injection on the day before surgery would offer the advantages of increased scheduling flexibility and decreased radiation exposure to the patient and operating room staff. We hypothesized that a single injection of radiolabeled colloid given 24 hours before surgery would be sufficient and would possibly improve intraoperative sentinel lymph node identification.

PATIENTS AND METHODS

Ninety-five patients with newly diagnosed cutaneous melanoma underwent injection of radiolabeled colloid and lymphoscintigraphy 18 to 24 hours before surgery for sentinel lymph node mapping and biopsy. Sixty-three patients underwent repeat imaging immediately before surgery, and the images were compared with those obtained the previous day. Intraoperative mapping utilized a hand-held gamma probe and injection of blue dye to identify sentinel lymph nodes.

RESULTS

Two hundred fifty-one sentinel lymph nodes were identified by initial lymphoscintigraphy in 95 patients. Delayed imagingwithout reinjection of radiolabeled tracer compared with the initial lymphoscintigraphy demonstrated no change (71%), clarification of initial ambiguous patterns (10%), or newly identified nodes (19%). Two hundred sixty-one sentinel lymph nodes were resected, of which 79% stained blue. Microscopic metastases were present in 20 sentinel lymph nodes (8%) in 19 patients (20%). All positive nodes contained radioactivity and blue dye.

CONCLUSIONS

A single injection of radiocolloid 24 hours before surgery combined with intraoperative blue dye injection identified all sentinel lymph nodes and did not miss any metastatic disease. In addition, delayed imaging may clarify initial ambiguous findings and identify additional nodes at risk for metastasis. This technique produces sentinel lymph node identification rates, harvest rates, and rates of positivity comparable to those reported with the use of injection of radiolabeled tracer on the day of surgery and greatly facilitates the technical and administrative aspects of sentinel lymph node mapping.

Identification of higher risk thin melanomas should be based on Breslow depth not Clark level IV

BACKGROUND

There is good prognostic correlation for the two microstaging systems, Breslow depth and Clark level, commonly used to stage melanomas. Many investigators have reported that Breslow depth is the superior microstaging method. Although Clark level has been dropped from most of the proposed American Joint Committee on Cancer (AJCC) melanoma staging system, the AJCC system still includes Clark Level IV as a criterion for upstaging thin melanomas. The authors sought to determine whether this is appropriate, based on melanoma patient data in the Duke Comprehensive Cancer Center database.

METHODS

Of the 8833 patients registered between January 1, 1970 and December 31, 1995, complete data on Breslow depth and Clark level was available for 4560 patients who were without nodal or metastatic disease at presentation. Ten-year survival was measured from the date of excision of the primary tumor until death from melanoma and analyzed using Kaplan-Meier and Cox proportional hazard methodologies.

RESULTS

When analyzed separately, both increased Breslow thickness and Clark level correlated with shorter survival times. During subgroup analysis, Breslow thickness remained a significant prognostic indicator of survival at Clark Levels III and IV. Conversely, at narrow levels of Breslow thickness (i.e., 0-0.75 mm, > 0.75 -1.0 mm, > 1.0-1.5 mm) survival times were indistinguishable between Clark Levels III and IV. For the broader Breslow thickness interval of 0-1.0 mm, a barely significant difference between Clark Levels III and IV could be obtained. However, for this thickness range, even greater differences in survival could be obtained by merely comparing Breslow subgroups (i.e., < or = 0.8 mm vs. > 0.8-1.0 mm, < or = 0.9 mm vs. > 0.9-1.0 mm).

CONCLUSION

The authors' data suggested that, after controlling for Breslow depth, Clark level was not a good prognostic indicator for survival. If the AJCC's objective is to design a classification system that will reliably predict the higher risk melanomas, then the system should be based on tumor thickness, which is clearly a better prognostic indicator, and should not be modified because of Clark level.

Management of node-positive melanoma in the era of sentinel node biopsy

Regional lymph node metastasis is a powerful predictor of decreased overall survival from malignant melanoma. However, the therapeutic value of elective node dissections and the role of adjuvant therapy for node-positive disease have been highly controversial. Sentinel lymph node biopsy has reshaped the debate by allowing for staging of the regional lymph nodes with less morbidity and greater accuracy. This review summarizes the current consensus on the management of node-positive melanoma in the era of sentinel lymph node biopsy.

Gastrointestinal carcinoids: characterization by site of origin and hormone production

OBJECTIVE

To describe a large series of patients with carcinoid tumors in terms of presenting symptoms, hormonal data, stage at diagnosis, pathologic features, and survival.

SUMMARY BACKGROUND DATA

Published series have described significant prognostic features of carcinoid tumors as site of origin, age, sex, stage at diagnosis, presence of high hormone levels, and increased T stage. Of these, stage at diagnosis and T stage seem to emerge most often as independent predictors of survival in multivariate analyses. Of carcinoid tumors, those arising from a midgut location have higher levels of serotonin and serotonin breakdown products, as well as more frequent metastatic disease at presentation, than those arising from either foregut or hindgut locations.

METHODS

A prospective database of carcinoid patients seen at Duke University Medical Center was kept from 1970 to the present. Retrospective medical record review was performed on this database to record presenting symptoms, hormonal data, pathologic features, and survival. Statistical methods included analysis of variance, Kaplan-Meier analysis, and Mantel-Cox proportional hazard survival analysis, with P <.05 considered significant for all tests.

RESULTS

Carcinoids arising in different locations had different presentations: rectal carcinoids presented significantly more often with gastrointestinal bleeding, and midgut carcinoids presented significantly more often with flushing, diarrhea, and the carcinoid syndrome. Patients with midgut tumors had significantly higher levels of serotonin and serotonin breakdown products, corresponding to higher metastatic tumor burdens. Although age, stage, region of origin, and urinary level of 5-hydroxyindoleacetic acid predicted survival by univariate analysis, only the latter three were independent predictors of survival by multivariate analysis. Of the patients with metastatic disease at diagnosis, those with midgut tumors had better survival than those with foregut or hindgut tumors.

CONCLUSIONS

Although region of origin is certainly an important factor in determination of prognosis, stage of disease at presentation is more predictive of survival. Pancreatic and midgut carcinoids are metastatic at diagnosis more often than those arising in other locations, leading to a worse overall prognosis. Among patients with distant metastases, patients with midgut primary tumors have improved survival despite increased hormone production compared with patients with tumors arising in other primary sites.

Positron emission tomography scanning in malignant melanoma

BACKGROUND

Several recent studies have demonstrated the low yield of anatomically based computed tomography scans in evaluating Stage III (American Joint Committee on Cancer) patients with malignant melanoma. The purpose of this study was to investigate the efficacy and clinical utility of functionally based positron emission tomography (PET) scans in the same patient population.

METHODS

A prospective evaluation of 106 whole body PET scans obtained after injection of 2-fluorine-18, 2-fluoro-2-deoxy-D-glucose (FDG) was performed in 95 patients with clinically evident Stage III lymph node and/or in-transit melanoma. Areas of abnormality on FDG PET scanning were identified visually as foci of increased metabolic activity compared with background, and all positive foci were assessed pathologically.

RESULTS

In this patient population, there were 234 areas that were evaluated pathologically of which 165 were confirmed histologically to be melanoma. PET scanning identified 144 of the 165 areas of melanoma for a sensitivity of 87.3%. The 21 areas of melanoma that were missed included 10 microscopic foci, 9 foci less than 1 cm, and 2 foci greater than 1 cm. There were 39 areas of increased PET activity that were not associated with malignancy for a 78.6% predictive value of a positive test. Of the 39 false-positive areas (false-positive rate of 56.5%), 13 could be attributed to recent surgery, 3 to arthritis, 3 to infection, 2 to superficial phlebitis, 1 to a benign skin nevus, and 1 to a colonic polyp. Pathologic evaluation of the remaining false-positive areas failed to reveal a definitive etiology for their increased activity on PET scan. With the application of pertinent clinical information, the predictive value of a positive PET scan could be improved to 90. 6%. The specificity of PET scanning in this study was only 43.5% because very few prophylactic lymph node dissections were performed. Thirty-six of the total 183 abnormal areas (19.7%) on PET scanning proved to be unsuspected areas of metastatic disease. These findings led to a change in the planned clinical management in patients after 16 of the 106 PET scans (15.1%).

CONCLUSIONS

FDG PET scanning can be helpful in managing patients with Stage III melanoma in whom further surgery is contemplated. Although false-positive areas are not uncommon, PET scans did change the management of patients 15% of the time. PET's inability to identify microscopic disease suggests that it is of limited use in evaluating patients with Stage I-II disease.

Local ampullary resection with careful intraoperative frozen section evaluation for presumed benign ampullary neoplasms

BACKGROUND

Frozen section evaluation has been reported to be inaccurate in detecting foci of adenocarcinoma within adenomas of the ampulla of Vater, leading many authors to advocate pancreaticoduodenectomy as the method of treatment for these neoplasms. The authors hypothesized that (1) ampullary resection is less morbid than pancreaticoduodenectomy, and (2) frozen section evaluation following ampullary resection is accurate and allows for a selective application of pancreaticoduodenectomy to those with carcinoma or benign lesions too large to be locally resected.

METHODS

A retrospective review of a single-surgeon experience was conducted. Thirty-eight patients who underwent ampullary resection and pancreaticoduodenectomy (39 procedures) for benign and malignant ampullary neoplasms were identified. Our technique of step-frozen section analysis is described.

RESULTS

Twenty-one ampullary resections were performed for preoperative diagnoses of benign (16) and malignant (5) ampullary neoplasms. Frozen section evaluation accurately predicted the final histology in all patients undergoing ampullary resection. Ampullary resection (vs pancreaticoduodenectomy) was associated with a statistically lower operative time (169 minutes vs 268 minutes), estimated blood loss (192 mL vs 727 mL), mean length of stay (10 days vs 25 days), and overall morbidity (29% vs 78%).

CONCLUSIONS

Frozen section evaluation of ampullary neoplasms is accurate. Because ampullary resection is less morbid than pancreaticoduodenectomy and frozen section evaluation is accurate, ampullary resection with frozen section evaluation is our current approach to the treatment of small benign ampullary neoplasms.

Foregut carcinoids: a clinical and biochemical analysis

BACKGROUND

Gastrointestinal foregut carcinoids make up a small percentage (3% to 6%) of all reported carcinoids. Because these tumors are so uncommon, comparisons between the subtypes have been difficult. The goal of this study was to compare the hormonal and clinical characteristics of gastric, duodenal, and pancreatic carcinoids.

METHODS

A prospective database of approximately 750 carcinoid patients seen by one author over 25 years was reviewed, and the 104 patients with gastric (33), duodenal (17), or pancreatic (54) carcinoids were selected as the subgroup for analysis. These patients were compared with regard to hormone levels, clinical course, treatment, and survival.

RESULTS

Duodenal carcinoids exhibited significantly lower serotoninergic hormone levels than did the gastric and pancreatic carcinoids (urine 5-hydroxyindoleacetic acid [mg/24 h], 5 +/- 1 vs 16 +/- 5 and 47 +/- 12, respectively, P = .03). Pancreatic carcinoids presented with more advanced stage (distant metastases 87% vs 42% and 20% for gastric and duodenal, respectively) and had worse outcomes than patients with gastric and duodenal tumors with 10-year survivals of 10%, 59%, and 58%, respectively (P = .003).

CONCLUSIONS

Pancreatic carcinoids produce higher levels of serotoninergic hormones and have a significantly higher stage and worse outcome than other foregut carcinoids. This study demonstrates that the organ of origin is an important determinant of hormonal activity and clinical course for patients with foregut carcinoids.

Follicular neoplasms: the role for observation, fine needle aspiration biopsy, thyroid suppression, and surgery

The diagnosis and management of follicular carcinoma of the thyroid gland remains a controversial topic. Fine needle aspiration, although very sensitive with other types of thyroid cancer, has limited accuracy with follicular lesions. The role of suppression combined with observation has yet to gain widespread acceptance. The extent of surgical excision of follicular carcinoma also raises several competing views. The goal of this review is to address these issues and present an algorithm for the management of follicular neoplasms of the thyroid.

Carcinoids of unknown origin: comparative analysis with foregut, midgut, and hindgut carcinoids

BACKGROUND

Carcinoids are rare neuroendocrine tumors typically arising in the gastrointestinal tract. A significant percentage of these tumors present as metastatic disease of unknown primary site. The aim of this study was to better define the functional and clinical characteristics of carcinoids of unknown primary (CUP) site.

METHODS

This study examines the hormonal activity, clinical characteristics, and survival of 434 patients with carcinoids originating in the foregut, midgut, hindgut, or unknown location. The 143 patients with CUP were compared with the other groups with regard to presenting characteristics, diagnostic tests and therapeutic modalities used, hormonal activity, and survival.

RESULTS

The hormone levels (urinary 5-hydroxyindoleacetic acid and serotonin, serum and platelet serotonin) of CUP were not significantly different from midgut carcinoids with metastatic disease. Although survival with CUP was shorter than with carcinoids with identified primaries (10-year survivals of 22% vs 62%, 50%, and 48% for foregut, midgut, and hindgut, respectively), the survival curve for CUP was quite similar to that of patients with midgut carcinoids with distant disease (10-year survival of 22% vs 28%).

CONCLUSIONS

CUP are similar to midgut carcinoids presenting with metastatic disease with regard to hormone production and survival. Like other carcinoids, CUP can be an indolent disease process with gradual progression over decades.

Malignant melanoma of the mucous membranes: a review of 119 cases

BACKGROUND

Melanomas arising from the mucous membranes lining the respiratory, digestive, and genitourinary tracts are rare. Women are more commonly affected than are men, mainly because there is no male counterpart for vulvovaginal lesions. The mainstay of therapy is surgery, with little current use of adjuvant modalities in primary therapy. These lesions usually are advanced at initial presentation; consequently, the prognosis is poor, with 5-year survivals well below 50% in most series.

METHODS

One hundred and nineteen patients with primary mucosal melanoma were reviewed. They represented 1.1% of the 10,393 melanoma patients seen at Duke University between 1970 and 1995. All data were obtained from the patients' clinic charts and computerized databases.

RESULTS

There were 43 tumors arising from the head and neck region, 46 from the urogenital tract, and 30 from the anorectum. A female predominance was observed, with a female-to-male ratio of 2.7:1. All but five of the patients underwent resection with curative intent. Regional or distant metastases, or both, were encountered in 36 patients at the time of presentation. In patients with head and neck and urogenital tumors, local recurrences accounted for most of the treatment failures, whereas systemic recurrences were more common with tumors arising in the anorectum. The age and gender of the patient, anatomic site of origin of the tumor, clinical stage at initial presentation, and ulceration of the primary all clearly affected prognosis. Overall, the probabilities of being alive 1, 5, and 10 years after diagnosis were 80%, 29%, and 15%, respectively.

CONCLUSIONS

Widely accepted classification systems are needed so that results from separate institutions can be compared adequately. Multi-institutional trials could help in delineating standardized therapeutic protocols and in establishing the potential roles of emerging modalities in the treatment of this subtype of melanoma.

Lymphokine-activated killer (LAK) cell anti-HIV-1 ADCC reactivity: a potential strategy for reduction of virus-infected cellular reservoirs

Lymphocytes from HIV-1-seropositive and -seronegative individuals were examined to determine whether HIV-1 infection interfered with the ability to generate a lymphokine-activated killer (LAK) cell response. Following a 3-day ex vivo incubation in the presence of 1000 U/ml of recombinant interleukin-2, lymphocytes from seropositive individuals exhibited a LAK cell response which was equivalent to or greater than that of seronegative controls as measured against Daudi cell targets. LAK cells from seropositive and seronegative donors showed no specific cytolytic activity against gp120-coated or HIV-1-infected targets. However, in the presence of patient sera, significant levels of virus-specific LAK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) were observed. The level of this specific LAK cell-mediated ADCC was greater than that mediated under similar conditions by freshly isolated peripheral blood mononuclear cells. The greatest improvement in ADCC over baseline activity was seen with lymphocytes from AIDS patients after the 3-day ex vivo activation, suggesting that this patient population might benefit the most from adaptive LAK cell therapy.

The role of laparoscopy in the management of suspected pancreatic and periampullary malignancies

Laparoscopic evaluation of patients with suspected periampullary malignancies has been utilized more frequently in recent years. Its exact role with regard to staging and surgical bypass for palliation have yet to be clearly defined. To better define the role of laparoscopy in the evaluation and palliation of periampullary malignancy, a retrospective review of the Duke experience was carried out. Fifty-three patients with suspected pancreatic or periampullary malignancies were referred for surgical evaluation at Duke University Medical Center between 1993 and 1995. All patients underwent CT scanning and lesions were classified as resectable or unresectable based on previously established criteria. Patients either underwent laparoscopic evaluation (n = 30; 11 with laparoscopic palliation) or proceeded directly to celiotomy (n = 23). Charts were reviewed for postoperative course including complications, length of stay, and hospital costs. Although laparoscopy had a sensitivity of 93.3% for metastatic disease, CT scans accurately staged 86.8% of patients missing only one patient with peritoneal/hepatic disease. Based on these results, laparoscopy may not be beneficial for every patient with a suspected pancreatic malignancy. Retrospectively an attempt was made to determine which patients benefited from laparoscopy and which patients are best served by proceeding directly to open exploration. From these data we devised an algorithm that outlines an efficient and cost-effective approach for this patient population.

Asystole as a neurologic sign

The authors present a case of asystole occurring during dural closure following craniotomy with the patient in the supine position. This 22-year-old woman had a left parietal lobe tumor resected with bipolar cautery. Standard intraoperative monitoring with a left radial arterial line and a right internal jugular central venous catheter was used during the surgery. The anesthetic course was complicated by intraoperative bleeding that responded to three units of fresh frozen plasma. Prior to closure, the operative site appeared dry and intact. After closure, asystole occurred suddenly and resolved with evacuation of 500 ml of blood. It is speculated that the asystole was preceded by an acute increase in intracranial pressure and a subsequent secondary brainstem compression.

Preoperative radiation and chemotherapy in the treatment of adenocarcinoma of the rectum

OBJECTIVE

In this study, the impact of preoperative chemotherapy and radiation on the histopathology of a subgroup of patients with rectal adenocarcinoma was examined. As well, survival, disease-free survival and pelvic recurrence rates were examined, and compared with a concurrent control group.

SUMMARY BACKGROUND DATA

The optimal treatment of large rectal carcinomas remains controversial; current therapy usually involves abdominoperineal resection plus postoperative chemoradiation; the combination can be associated with significant postoperative morbidity. In spite of these measures, local recurrences and distant metastases continue as serious problems.

METHODS

Fluorouracil, cisplatin, and 4500 cGy were administered preoperatively over a 5-week period, before definitive surgical resection in 43 patients. In this group of patients, all 43 had biopsy-proven lesions > 3 cm (median diameter), involving the entire rectal wall (as determined by sigmoidoscopy and computed tomography scan), with no evidence of extrapelvic disease. The patients ranged from 31 to 81 years of age (median 61 years), with a male:female ratio of 3:1. A concurrent control group consisting of 56 patients (median: 62 years, male:female ration of 3:2) with T2 and T3 lesions was used to compare survival, disease-free survival, and pelvic recurrence rates.

RESULTS

The preoperative chemoradiation therapy was well tolerated, with no major complications. All patients underwent repeat sigmoidoscopy before surgery; none of the lesions progressed while patients underwent therapy, and 22 (51%) were determined to have complete clinical response. At the time of resection, 21 patients (49%) had gross disease, 9 (22%) patients had only residual microscopic disease, and 11 (27%) had sterile specimens. Of the 30 patients with evidence of residual disease, 4 had positive lymph nodes. In follow-up, 39 of the 43 remain alive (median follow-up = 25 months), and only 1 of the 11 patients with complete histologic response developed recurrent disease. Six of the 32 patients with residual disease (2 with positive nodes) have developed metastatic disease in follow-up (median time to diagnosis 10 months, range 3-15 months). Three of these patients with metastases have died (median survival after diagnosis of metastases = 36 months). Local recurrence was seen in only 2 of 43 patients (< 5%). Cox-Mantel analysis of Kaplan-Meier distributions demonstrated increased survival (p = 0.017), increased disease-free survival (p = 0.046), and decreased pelvic recurrence (p = 0.031) for protocol versus control patients.

CONCLUSIONS

This therapeutic regimen has provided enhanced local control and decreased metastases. Furthermore, the marked degree of tumor downstaging, as seen by a 27% incidence of sterile pathologic specimens and a low rate of positive lymph nodes in this group with initially advanced lesions, strongly suggest that less radical surgery and sphincter preservation may be used with increasing frequency.

Interleukin-1 production in tumor cells of human melanoma surgical specimens

To determine whether IL-1 alpha and/or IL-1 beta protein is expressed by human melanoma tumor in vivo, we first analyzed nine human melanoma cell lines and optimized the in situ detection of these proteins. Three of the melanoma cell lines stained positively for both IL-1 alpha and IL-1 beta using immunohistochemistry (IHC). THe specificity of IHC was confirmed by the ability of purified recombinant IL-1 alpha and IL-1 beta protein to abolish the staining after being adsorbed by their respective antibodies before use in IHC. The three positively staining cell lines were also the only lines to demonstrate IL-1 production by western blot analysis as well as IL-1 secretion by ELISA. Next we examined 29 surgically obtained melanoma tumor specimens (6 primary and 23 metastases) that had been formalin fixed and paraffin embedded. Using the same anti-IL-1 antibodies, 5 of 23 metastatic tumors stained positively. None of the 6 primary lesions stained for either IL-1 alpha or IL-1 beta. Comparison of staining pattern performed on serially sectioned tissue using preimmune serum and antibodies against S-100 protein, melanoma-associated antigen (HMB-45), and CD68 (kappa P1), which recognizes monocyte-macrophage cell lineage, demonstrates for the first time that IL-1 protein is produced by human melanoma tumor cells in vivo. These findings provide the basis for examination of what may be a previously unrecognized biologically distinct subset of patients.

Indeterminate fine-needle aspiration biopsy of the thyroid: identification of subgroups at high risk for invasive carcinoma

BACKGROUND

We examined the various cytologic features of indeterminate thyroid fine-needle aspirates along with known clinical and radiologic risk factors to determine whether any parameters were predictive of malignancy.

METHODS

Indeterminate fine-needle aspirates were prospectively categorized into four subgroups: (1) suspicious for papillary carcinoma, (2) follicular neoplasm, (3) Hürthle cell neoplasm, and (4) hypercellular follicular aspirates with colloid. Several clinical risk factors were examined, and subgroup comparisons were performed with Fisher's exact test.

RESULTS

Of 571 fine-needle aspirate cytologic findings 104 were interpreted as indeterminate for malignancy, and 81 patients underwent thyroidectomy. Invasive cancer was diagnosed in 9 of 10 lesions cytologically suspicious for papillary carcinoma, 8 of 43 follicular neoplasms, 5 of 18 Hürthle cell neoplasms, and 0 of 10 hypercellular aspirates. Cytologic subgroup (p < 0.0001) and age of 50 years or older (p = 0.008) were the only significant predictors of malignancy. When used together, age of 50 years or older and a cytologic diagnosis of follicular or Hürthle cell neoplasm also identified a subgroup of patients at high risk (9 of 20) of invasive malignancy (p = 0.01).

CONCLUSIONS

The majority of invasive cancers (18 of 22, 82%) were found in patients whose lesions were suspicious for papillary carcinoma or in patients 50 years or older with follicular or Hürthle cell neoplasms. The risk of carcinoma in these combined subgroups (18 of 30, 60%) warrants early surgical intervention.

Reoperative pancreaticoduodenectomy

OBJECTIVE

The preoperative diagnostic strategy and operative technique for reoperative pancreaticoduodenectomy were outlined and operative mortality, perioperative morbidity, and early survival data in carefully selected patients undergoing reoperation for pancreatic cancer were analyzed.

SUMMARY BACKGROUND DATA

Many patients with localized, nonmetastatic cancer of the pancreas undergo exploratory surgery with limited preoperative assessment of resectability. Frequently, pancreaticoduodenectomy is not performed because cytologic or histologic proof of diagnosis is lacking, or tumor resectability is questioned. Many patients are denied reoperation and a potentially curative resection because of the unacceptable morbidity and mortality believed to accompany pancreaticoduodenectomy in the reoperative setting.

METHODS

Twenty-three patients who had undergone previous surgery for palliation or diagnosis of a pancreatic head mass were reoperated on after a standardized preoperative imaging evaluation consisting of chest radiography, computed tomography, and visceral angiography. A standardized operative technique was used on all patients, but was modified based on altered anatomy from the initial operation.

RESULTS

Based on preoperative imaging studies, 19 of the 23 patients believed to have resectable tumors underwent laparotomy for planned pancreaticoduodenectomy; resection was accomplished in 14 patients. Seven of the fourteen patients required extended resections that included the superior mesenteric vein, right colon, or both. There was no perioperative mortality, and early complications occurred in 3 of the 14 resected patients. Four patients underwent planned palliative procedures. Four of ten patients who underwent resection for adenocarcinoma are without evidence of disease at a median follow-up of 26 months.

CONCLUSIONS

Reoperative pancreaticoduodenectomy can be performed safely and may result in prolonged survival in carefully selected patients with resectable, localized pancreatic cancer.

The effect of AZT on in vitro lymphokine-activated killer (LAK) activity in human immunodeficiency virus type-1 (HIV-1) infected individuals

Human immunodeficiency virus type-1 (HIV-1)-infected individuals exhibit functional impairment in various forms of cell-mediated cytotoxicities (CMC) at all stages of disease. The purpose of this study was to determine (i) if peripheral blood mononuclear cells (PBMC) obtained from HIV-1-infected patients could be stimulated in vitro to yield lymphokine-activated killer (LAK) activity; (ii) if non-MHC-restricted gp120-specific CMC could be preserved; and (iii) what effect zidovudine (AZT) would have on LAK activity. Fourteen asymptomatic HIV-1 seropositive adults and five healthy seronegative adults (controls) were evaluated. PBMCs were isolated and incubated in media or supplemented with IL-2 for 4 or 72 hr. Lysis of the NK resistant target cell line, Daudi, was similar for the control and experimental group. The increase in activity after stimulation was elevated to a similar degree in both seronegative and seropositive groups (P less than 0.001). LAK activity was significantly decreased (P = 0.011) when AZT was added to LAK cultures. In addition, virus production may not have been completely inhibited by AZT in LAK cultures. Thus, PBMCs from asymptomatic HIV-1-infected patients could be stimulated to yield LAK activity. However, AZT can impair LAK generation. It is unclear if LAK activation results in virus production that cannot be inhibited by AZT in this system. Further definition in other patient populations is required prior to applying this information to clinical trials.

Identification of sites within gp41 that serve as targets for antibody-dependent cellular cytotoxicity by using human monoclonal antibodies

In an effort to determine the functional activity of anti-HIV-1 human mAb and to define the epitopes against which they are directed, supernatants from 10 EBV-transformed lymphoblastoid cell lines producing mAb to HIV were tested. Five clones producing mAb to gp41 and five producing mAb to p24 were identified. The anti-HIV-1 human mAb were tested in neutralization and cell fusion assays in the form of cell culture supernatants at concentrations ranging from 1.7 to 22.0 micrograms/ml. None of the human mAb were found either to inhibit HIV-1-(IIIB or RF) associated cell fusion or to neutralize HIV-1 (IIIB) infection of AA5 cells. All human mAb were additionally tested in 6 h 51Cr release assays for their ability to direct HIV-1 specific antibody-dependent cellular cytotoxicity (ADCC). For ADCC assays, PBMC were isolated from healthy seronegative donors and used as effector cells. HIV-1 infected (IIIB, RF, and MN) CEM.NKR cells as well as CEM.NKR cells with purified gp120 adsorbed onto their surface served as targets. None of the anti-p24 mAb mediated ADCC. In contrast, three of the anti-gp41 mAb were able to direct a significant level of ADCC against each of the infected targets, but as expected, failed to lyse gp120 adsorbed cells. To define the specific epitopes against which the anti-gp41 mAb were directed, seven small peptides homologous to regions within the extracellular domain of gp41 were synthesized. Using RIA, two of the mAb could be mapped. The most effective ADCC-directing human mAb bound to a peptide comprising amino acids 644-663, whereas the least effective ADCC directing anti-gp41 human mAb bound to a region within the immunodominant portion of gp41 outlined by amino acids 579-604. Together, these results for the first time assign a functional activity to human mAb directed at specific regions within gp41 by demonstrating that areas within this molecule can serve as targets for ADCC.

Identification of sites within gp41 that serve as targets for antibody-dependent cellular cytotoxicity by using human monoclonal antibodies

In an effort to determine the functional activity of anti-HIV-1 human mAb and to define the epitopes against which they are directed, supernatants from 10 EBV-transformed lymphoblastoid cell lines producing mAb to HIV were tested. Five clones producing mAb to gp41 and five producing mAb to p24 were identified. The anti-HIV-1 human mAb were tested in neutralization and cell fusion assays in the form of cell culture supernatants at concentrations ranging from 1.7 to 22.0 micrograms/ml. None of the human mAb were found either to inhibit HIV-1-(IIIB or RF) associated cell fusion or to neutralize HIV-1 (IIIB) infection of AA5 cells. All human mAb were additionally tested in 6 h 51Cr release assays for their ability to direct HIV-1 specific antibody-dependent cellular cytotoxicity (ADCC). For ADCC assays, PBMC were isolated from healthy seronegative donors and used as effector cells. HIV-1 infected (IIIB, RF, and MN) CEM.NKR cells as well as CEM.NKR cells with purified gp120 adsorbed onto their surface served as targets. None of the anti-p24 mAb mediated ADCC. In contrast, three of the anti-gp41 mAb were able to direct a significant level of ADCC against each of the infected targets, but as expected, failed to lyse gp120 adsorbed cells. To define the specific epitopes against which the anti-gp41 mAb were directed, seven small peptides homologous to regions within the extracellular domain of gp41 were synthesized. Using RIA, two of the mAb could be mapped. The most effective ADCC-directing human mAb bound to a peptide comprising amino acids 644-663, whereas the least effective ADCC directing anti-gp41 human mAb bound to a region within the immunodominant portion of gp41 outlined by amino acids 579-604. Together, these results for the first time assign a functional activity to human mAb directed at specific regions within gp41 by demonstrating that areas within this molecule can serve as targets for ADCC.

Alterations in antibody-dependent cellular cytotoxicity during the course of HIV-1 infection. Humoral and cellular defects

HIV-1-specific cell-mediated cytotoxicity (CMC) is a form of antibody-dependent cellular cytotoxicity (ADCC) in which HIV-1-specific antibodies arm NK cells directly to become cytotoxic for targets bearing HIV-1 antigenic determinants. This non-MHC-restricted cytotoxic activity is present in early stages of disease and declines markedly with disease progression. To understand the cellular and humoral factors contributing to the reduction in this activity, the conditions under which maximal arming of cells occurs was examined in vitro. With the use of a large patient cohort, a strong positive correlation was found between the capacity of a serum to direct lysis in standard ADCC assays and its ability to arm NK cells. Patients with minimal HIV-1-specific ADCC-directing antibodies exhibited low levels of CMC and were unable to arm normal effector cells in vitro. The lack of sufficient ADCC-directing antibodies was found to be one cause of defective CMC in some patients. Unlike asymptomatics, only a weak positive correlation was found between arming and ADCC with sera from AIDS patients, indicating that a factor other than absolute HIV-1 specific antibody titer was responsible for decreased CMC in this patient population. Another group of patients was found to have diminished CMC despite the presence of antibodies in the serum that were fully capable of arming normal effector cells to become cytotoxic for gp120-expressing targets. When compared with those of normal individuals, lymphocytes from seropositive patients mediated significantly reduced levels of cytotoxicity in ADCC and arming assays with the use of a high titered HIV-1-specific serum. In both assay systems, the magnitude and frequency of dysfunction in antibody-dependent cytolysis was found to be greater among AIDS patients than among asymptomatic individuals. The demonstration of both cellular and humoral defects in the ability of seropositive individuals to manifest ADCC reactivities strongly suggests that HIV-1 infection may significantly compromise the effectiveness of this potentially important cytolytic reactivity in vivo.

Alterations in antibody-dependent cellular cytotoxicity during the course of HIV-1 infection. Humoral and cellular defects

HIV-1-specific cell-mediated cytotoxicity (CMC) is a form of antibody-dependent cellular cytotoxicity (ADCC) in which HIV-1-specific antibodies arm NK cells directly to become cytotoxic for targets bearing HIV-1 antigenic determinants. This non-MHC-restricted cytotoxic activity is present in early stages of disease and declines markedly with disease progression. To understand the cellular and humoral factors contributing to the reduction in this activity, the conditions under which maximal arming of cells occurs was examined in vitro. With the use of a large patient cohort, a strong positive correlation was found between the capacity of a serum to direct lysis in standard ADCC assays and its ability to arm NK cells. Patients with minimal HIV-1-specific ADCC-directing antibodies exhibited low levels of CMC and were unable to arm normal effector cells in vitro. The lack of sufficient ADCC-directing antibodies was found to be one cause of defective CMC in some patients. Unlike asymptomatics, only a weak positive correlation was found between arming and ADCC with sera from AIDS patients, indicating that a factor other than absolute HIV-1 specific antibody titer was responsible for decreased CMC in this patient population. Another group of patients was found to have diminished CMC despite the presence of antibodies in the serum that were fully capable of arming normal effector cells to become cytotoxic for gp120-expressing targets. When compared with those of normal individuals, lymphocytes from seropositive patients mediated significantly reduced levels of cytotoxicity in ADCC and arming assays with the use of a high titered HIV-1-specific serum. In both assay systems, the magnitude and frequency of dysfunction in antibody-dependent cytolysis was found to be greater among AIDS patients than among asymptomatic individuals. The demonstration of both cellular and humoral defects in the ability of seropositive individuals to manifest ADCC reactivities strongly suggests that HIV-1 infection may significantly compromise the effectiveness of this potentially important cytolytic reactivity in vivo.

GP120 specific cellular cytotoxicity in HIV-1 seropositive individuals. Evidence for circulating CD16+ effector cells armed in vivo with cytophilic antibody

Fresh circulating PBMC from HIV-1 seropositive individuals have been found to mediate specific, non-MHC restricted lysis of targets expressing the major envelope glycoprotein of HIV-1, gp120, in 6-h 51Cr release assays. This gp120 specific cell-mediated cytotoxicity (CMC) is broadly reactive against target cells infected with a wide range of viral isolates, is IL-2 augmentable, and is mediated by a CD16+, Leu-7+, CD15-, CD3- population of NK/K cells. The presence of FcR (CD16) on these cells suggested that the lytic specificity for gp120 might be directed by cytophilic antibody bound to the cell surface. Affinity purified F(ab')2 antibody fragments specific for the Fc and F(ab')2 portions of human IgG were used in attempts to block gp120 specific lysis. A 1/50 dilution of these antibodies inhibited gp120 specific cytolytic activity by more than 90% while exhibiting a minimal effect on NK/K cell lysis of K562 targets. The blocking activity of these fragments demonstrates the direct involvement of cytophilic antibody in CMC. In attempts to isolate this cytophilic anti-HIV-1 antibody, short 56 degrees C incubations were used to dissociate antibodies from the surface of PBMC of seropositive individuals. The supernatants generated in this manner exhibited specific gp120 activity in antibody-dependent cellular cytotoxicity assays. The ability of Staphylococcal protein A to remove this activity confirms the presence of cytophilic antibody on freshly isolated PBMC. Selective enrichment of specific cell subpopulations revealed the origin of the cytophilic antibody to be CD16+ NK/K cells and not B cells, T cells, or monocytes/macrophages. These studies show that the gp120-specific CMC seen in HIV-1 seropositive individuals is directed by cytophilic antibody bound to circulating CD16+ NK/K cells and represents a form of direct antibody-dependent cellular cytotoxicity which may provide a primary cytotoxic host defense.

GP120 specific cellular cytotoxicity in HIV-1 seropositive individuals. Evidence for circulating CD16+ effector cells armed in vivo with cytophilic antibody

Fresh circulating PBMC from HIV-1 seropositive individuals have been found to mediate specific, non-MHC restricted lysis of targets expressing the major envelope glycoprotein of HIV-1, gp120, in 6-h 51Cr release assays. This gp120 specific cell-mediated cytotoxicity (CMC) is broadly reactive against target cells infected with a wide range of viral isolates, is IL-2 augmentable, and is mediated by a CD16+, Leu-7+, CD15-, CD3- population of NK/K cells. The presence of FcR (CD16) on these cells suggested that the lytic specificity for gp120 might be directed by cytophilic antibody bound to the cell surface. Affinity purified F(ab')2 antibody fragments specific for the Fc and F(ab')2 portions of human IgG were used in attempts to block gp120 specific lysis. A 1/50 dilution of these antibodies inhibited gp120 specific cytolytic activity by more than 90% while exhibiting a minimal effect on NK/K cell lysis of K562 targets. The blocking activity of these fragments demonstrates the direct involvement of cytophilic antibody in CMC. In attempts to isolate this cytophilic anti-HIV-1 antibody, short 56 degrees C incubations were used to dissociate antibodies from the surface of PBMC of seropositive individuals. The supernatants generated in this manner exhibited specific gp120 activity in antibody-dependent cellular cytotoxicity assays. The ability of Staphylococcal protein A to remove this activity confirms the presence of cytophilic antibody on freshly isolated PBMC. Selective enrichment of specific cell subpopulations revealed the origin of the cytophilic antibody to be CD16+ NK/K cells and not B cells, T cells, or monocytes/macrophages. These studies show that the gp120-specific CMC seen in HIV-1 seropositive individuals is directed by cytophilic antibody bound to circulating CD16+ NK/K cells and represents a form of direct antibody-dependent cellular cytotoxicity which may provide a primary cytotoxic host defense.

Cellular anti-GP120 cytolytic reactivities in HIV-1 seropositive individuals

Forty-one patients seropositive for human immunodeficiency virus type 1 (HIV-1) were assessed for cell-mediated cytotoxicity (CMC) against autologous target cells bearing the major envelope glycoprotein of HIV-1, gp120. Effector lymphocytes from over 85% of seropositive patients showed CMC specific for gp120-coated targets, whereas seronegative individuals had no detectable CMC. As a group, symptomless individuals had the highest levels of CMC; patients with AIDS-related complex and AIDS showed progressively diminished reactivity. The gp120-specific CMC was mediated by a population of non-T-cell effectors phenotypically resembling NK/K cells. Cytolysis was not restricted by major histocompatibility complex determinants, as shown by killing of heterologous gp120-adsorbed targets and of HIV-1-infected cell-lines. Gp120-specific CMC was highly augmented in the presence of interleukin 2, so it may be possible to develop therapeutic strategies aimed at destruction of virus-producing cell reservoirs in infected individuals through stimulation of HIV-specific host CMC.

Cyclosporine and experimental skin allografts: long-term survival in rats treated with low maintenance doses

Although cyclosporine (CsA) is a powerful immunosuppressive agent in organ transplantation, its efficacy in skin transplantation has not been examined completely. We have tested it as primary immunosuppression in a rat skin allograft model. Histoincompatible Brown-Norway skin grafts are rejected in untreated Lewis hosts within 9 +/- 1 days but survive for 22 +/- 3, 34 +/- 2, or 41 +/- 8 days after 7, 14, or 21 days of CsA treatment (15 mg/kg per day subcutaneously), respectively (p less than 0.001). Animals treated daily for 4 weeks died from drug toxicity; however, an initial 2-week course followed by a low maintenance dose (15 mg/kg every fourth day) produced indefinite (greater than 150 days) graft acceptance without side effects. The long-surviving grafts were supple, grew long hair, and showed normal histology. When the drug was stopped at any time during this maintenance period, early signs of rejection (hair loss, epidermal breakdown, and localized ulceration) occurred, which could be reversed completely by a short CsA "pulse" (15 mg/kg per day for 7 days). These experimental data support the potential application of CsA immunosuppression in human skin allotransplantation.