FDG-PET and stereotactic body radiotherapy (SBRT) for stage I non-small-cell lung cancer

PURPOSE

To investigate the utility of positron emission tomography (PET) in patients treated with stereotactic body radiotherapy (SBRT) for stage I non-small-cell lung cancer (NSCLC) on prospective institutional trials.

PATIENTS AND METHODS

Fifty-eight patients with medically inoperable stage I NSCLC who participated in prospective phase I and II trials of SBRT, had >or=2 years of follow-up, and received FDG-PET imaging are the focus of this evaluation. Fifty-seven of 58 patients received pre-SBRT FDG-PET to confirm stage I status. All patients received stereotactic body frame immobilization and treatment with 7-10 photon beams. SBRT total doses ranged from 24 to 72Gy in three fractions. No elective nodal irradiation was undertaken. Regular follow-up with planned CT imaging was performed on all patients. Post-SBRT FDG-PET was not mandated by protocol and was typically ordered upon concern for disease recurrence. Thirty-eight post-SBRT PET studies were performed in 28 patients at a median 17.3 months following SBRT.

RESULTS

With a median follow-up of 42.5 months, the 3-year actuarial overall survival and local control for this select subset of our SBRT experience were 48.9% and 74.8%, respectively. Pre-SBRT FDG-PET SUV did not predict 3-year overall survival or local control. Fourteen of 57 patients eventually failed in nodal stations by CT and/or PET. Isolated first site of failure was nodal in 6 patients (10%). Out of 28 patients with post-SBRT PET, 4 (14%) had delayed PET imaging (22-26 months after SBRT) showing moderate hypermetabolic activity (SUV 2.5-5.07), but no evidence of local, nodal, or distant recurrence by clinical examination and conventional imaging performed 20-26 months following these concerning PET findings.

CONCLUSIONS

Isolated nodal recurrence following PET-staged I NSCLC treated with SBRT is uncommon. Moderate post-SBRT PET hypermetabolic activity may persist 2 years following treatment without definite evidence of recurrence. Further study is needed to confirm these results in larger populations with longer follow-up.

Iododeoxyuridine uptake in proliferating smooth muscle cells in vitro

PURPOSE

Iododeoxyuridine (IUdR) is a halogenated pyrimidine recognized as the thymidine substitute in DNA. When labeled with iodine 125, IUdR can be used as a carrier to incorporate the isotope into DNA and target the dividing cells. The purpose of this study was to assess the maximum uptake of IUdR by proliferating smooth muscle cells (SMCs) in vitro to determine the optimal concentration to be administered in an in vivo experiment. The long-term goal is to use radioactive IUdR to inhibit SMC proliferation and recurrent stenosis of arteries after balloon angioplasty in vivo.

MATERIALS AND METHODS

Porcine vascular SMCs were cultured in 5% fetal bovine serum medium and stimulated to proliferate by adding a medium containing 10% fetal bovine serum and insulin. IUdR was added to the proliferating SMCs at concentrations of 5, 10, 20, 30, and 40 micro mol/L on days 1, 3, 5, and 7 of incubation. One group of cells--the control group--did not receive IUdR. The SMCs were harvested and double-stained with an anti-IUdR antibody and propidium iodide, and fluorescence-activated cell scanning was performed to determine the ratio of IUdR-labeled cells to the total cell population for each IUdR concentration and at each time point. The data were measured three times at each time point. The doubling times, growth curve, and cell density of the proliferating SMCs were investigated by using the Coulter particle counter and digital microscopy.

RESULTS

The percentage of proliferating SMCs that showed IUdR uptake increased from 1 to 5 days incubation with all concentrations of IUdR; the incorporation rate reached a peak value at day 5 and then decreased by day 7. IUdR uptake on day 5 was higher with concentrations of 10 and 20 micro mol/L. When compared with that of the control group, the doubling times increased with an increase in IUdR concentration, whereas the proliferating cell number and density decreased significantly by days 5 (P < .05) and 7 (P < .01).

CONCLUSIONS

IUdR uptake peaked on day 5, and the optimal concentration of IUdR for in vitro uptake in proliferating SMCs was 10-20 micro mol/L. IUdR inhibited the proliferation of the SMCs, and the inhibitory effect was related to the concentration.

Extracranial Radiosurgery (Stereotactic Body Radiation Therapy) for Oligometastases

Extracranial radiosurgery, also known as stereotactic body radiation therapy (SBRT), is an increasingly used method of treatment of limited cancer metastases located in a variety of organs/sites including the spine, lungs, liver, and other areas in the abdomen and pelvis. The techniques used to perform SBRT were initially modeled after intracranial radiosurgery, although considerable evolution in technique and conduct has occurred for extracranial applications. Unlike intracranial radiosurgery, SBRT requires characterization and accounting for inherent organ movement including breathing motion. Potent dose hypofractionation schedules have been used with SBRT such that the treatment is generally both ablative and convenient. Because the treatment is severely damaging to tissues within and about the target, the volume of adjacent normal tissue must be strictly minimized to avoid toxic late effects. Outcomes in various sites show very high rates of local control with toxicity mostly related to tubular tissues like the airways and bowels. With proper conduct though, SBRT can be an extremely effective treatment option for oligometastases.

Stereotactic body radiation therapy of early-stage non-small-cell lung carcinoma: phase I study

PURPOSE

A Phase I dose escalation study of stereotactic body radiation therapy to assess toxicity and local control rates for patients with medically inoperable Stage I lung cancer.

METHODS AND MATERIALS

All patients had non-small-cell lung carcinoma, Stage T1a or T1b N0, M0. Patients were immobilized in a stereotactic body frame and treated in escalating doses of radiotherapy beginning at 24 Gy total (3 x 8 Gy fractions) using 7-10 beams. Cohorts were dose escalated by 6.0 Gy total with appropriate observation periods.

RESULTS

The maximum tolerated dose was not achieved in the T1 stratum (maximum dose = 60 Gy), but within the T2 stratum, the maximum tolerated dose was realized at 72 Gy for tumors larger than 5 cm. Dose-limiting toxicity included predominantly bronchitis, pericardial effusion, hypoxia, and pneumonitis. Local failure occurred in 4/19 T1 and 6/28 T2 patients. Nine local failures occurred at doses < or =16 Gy and only 1 at higher doses. Local failures occurred between 3 and 31 months from treatment. Within the T1 group, 5 patients had distant or regional recurrence as an isolated event, whereas 3 patients had both distant and regional recurrence. Within the T2 group, 2 patients had solitary regional recurrences, and the 4 patients who failed distantly also failed regionally.

CONCLUSIONS

Stereotactic body radiation therapy seems to be a safe, effective means of treating early-stage lung cancer in medically inoperable patients. Excellent local control was achieved at higher dose cohorts with apparent dose-limiting toxicities in patients with larger tumors.

Effect of Varying CT Section Width on Volumetric Measurement of Lung Tumors and Application of Compensatory Equations

PURPOSE

To determine how volume measurements of simulated and clinical lung tumors at standard computed tomographic (CT) lung window and level settings vary with section width and to derive and apply compensatory equations.

MATERIALS AND METHODS

Spherical simulated tumors of varying diameters were imaged with varying CT section widths, the images were displayed on a workstation, the cross-sectional area of the tumor on each section was measured by using elliptical and perimeter methods, and the areas were integrated to compute tumor volume. The actual and measured tumor volumes for differing section widths and tumor diameters were compared, and compensatory equations were derived. The equations were applied to contemporaneous chest CT images obtained in patients with stage I lung cancer, and the difference between thick- and thin-section-derived volumes before and after application of the equations was determined.

RESULTS

All simulated tumor volumes were overestimated 11%-278%; overestimation varied directly with section width and inversely with tumor diameter. With both measurement methods, mean thin-section volumes of clinical tumors in 55 patients were significantly smaller (P <.01) than mean thick-section volumes: Mean elliptical measurements were 15,025 mm3 (thin) and 18,037 mm3 (thick), with a 20.0% difference; mean perimeter measurements were 16,164 mm3 (thin) and 20,718 mm3 (thick), with a 22.2% difference. The thin-section-to-thick-section volume difference was larger for the smallest tumors. Thin-section volumes were smaller than thick-section volumes in 53 patients with the elliptical method and in 51 patients with the perimeter method. Applying the equations decreased the difference between thick- and thin-section volumes in 37 (67%) of the 55 patients with the elliptical method and in 41 (74%) patients with the perimeter method. The mean thin-section-to-thick-section volume difference became nonsignificant with the perimeter method but remained significant with the elliptical method.

CONCLUSION

Measured lung tumor volumes vary significantly with varying CT section width; overestimation varies directly with section width and inversely with tumor size. Compensatory equations that are somewhat effective in reducing these effects can be derived.

Dendritic cells transfected with interleukin-12 and pulsed with tumor extract inhibit growth of murine prostatic carcinoma in vivo

BACKGROUND

The induction of anti-tumor immune response by injection of dendritic cells loaded with specific antigen or transduced with genes encoding tumor-specific antigens have been studied in animal models and have shown promising anti-tumor effects. The impact of different routes of administration of dendritic cells on their anti-tumor effects is uncertain.

METHODS

We examined the effect of injection of cloned dendritic cells, which were stably transfected with IL-12 and exposed to an extract of murine RM-9 prostate carcinoma cell antigens on tumor growth in vivo. The cloned dendritic cells were injected intramuscularly, subcutaneously, or intraperitoneally into C57BL/6 mice. Seven days later, the mice were inoculated subcutaneously with 100,000 RM-9 cells. The sizes of the resulting tumors were measured every 3 days.

RESULTS

Compared with the wild type dendritic cells, the IL-12-transfected dendritic cells delayed tumor engraftment by 7 days (P=0.04), and reduced tumor growth by up to 80% (P=0.02). Among the three routes of injection, intramuscular injection was most effective. In contrast to wild type dendritic cells, IL-12-transfected dendritic cells induced infiltration of mononuclear cells into the tumors, and induced apoptosis and necrosis of tumor cells. Injection of IL-12-transfected dendritic cells also significantly delays tumor growth in the preexisting RM-9 tumors.

CONCLUSIONS

We conclude that antigen-exposed, IL-12-transfected dendritic cells have potential as an immunotherapy for prostate carcinoma. Routes of administration of dendritic cells are critical for maximal anti-tumor effect.

Observation-only management of early stage, medically inoperable lung cancer: poor outcome

STUDY OBJECTIVES

To assess the treatments received and outcomes of patients with early stage non-small cell lung carcinoma (NSCLC).

DESIGN

A retrospective study of patients identified from the institutional tumor registry between 1994 and 1999.

SETTING

The Richard L. Roudebush VA Medical Center, Indianapolis, IN.

PATIENTS

All patients with stage I and II NSCLC as identified above.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Of 128 patients identified, 49 patients received no cancer treatment, 36 patients received radiation therapy only, and 43 patients were treated with primary surgery. Median +/- SD survival time following surgery was 46.2 +/- 3.15 months; for no treatment, 14.2 +/- 2.37 months (p = 3.2 x 10(-6)); and radiotherapy alone, 19.9 +/- 5.6 months (p = 0.0005). Of those who received no specific cancer treatment, 14 patients refused treatment and the remainder were not treated for a variety of medical reasons. Cause of death was cancer in 53% of untreated patients and 43% for those receiving radiotherapy. Radiotherapy was administered for postobstructive atelectasis, hemoptysis, increasing tumor size, pain, pleural effusion, and medical inoperability. Radiation dosages had no apparent standard. No significant differences in survival were found for patients receiving radiotherapy with either curative or palliative intent (20.3 months vs 16.0 months, respectively; p = 0.229).

CONCLUSIONS

Within the limitations of this retrospective study, it appears that untreated early stage lung cancer has a poor outcome, with > 50% of patients dying of lung cancer. Surgery remains the treatment of choice, but lung cancer screening programs will result in increasing numbers of medically inoperable patients with no clear policies for their management.

Superior vena cava obstruction due to prostate carcinoma

Superior vena cava obstruction (SVCO) is considered an oncologic emergency commonly associated with lung carcinoma. The case presented here is that of a 48-year-old man presenting with SVCO, which was diagnosed as metastatic prostate carcinoma localized to the chest. He was treated with goserelin and aggressive radiotherapy with a drop in his prostate-specific antigen levels and symptomatic relief that lasted approximately 12 months. SVCO recurred locally in the chest and the patient died 24 months after diagnosis. This represents a rare presentation of prostate carcinoma and underlines the necessity for tissue diagnosis before local radiotherapy.

Treatment resistant small cell carcinoma of the cervix

BACKGROUND

Small cell undifferentiated carcinoma of the cervix is an uncommon malignancy with a poor prognosis. Treatment of localized disease has an approximate 40% 5-year survival with multimodality therapies.

CASE REPORT

We describe the case of a 24-year-old woman with small cell carcinoma of the cervix that recurred locally despite intensive chemotherapy and radiotherapy. Hysterectomy was performed and the patient is now 18 months disease free. Following treatment, the pathological appearance of the tumor had changed from a typical small cell neuroendocrine malignancy to a more intermediate neuroendocrine cell type.

CONCLUSION

Small cell carcinoma of the cervix is a rare aggressive malignancy that may require cytostatic multimodality therapy including chemotherapy, radiotherapy and surgery, even in early stage disease.

Optimal photon energies for IUdR K-edge radiosensitization with filtered x-ray and radioisotope sources

The purpose of this work is to determine the most physically effective radiation energy for K-edge absorption of x- or gamma-rays by iododeoxyuridine (IUdR) on Chinese hamster ovary (CHO) cells. Brachytherapy sources (Sm-145, I-125, Yb-169 and Am-241) and x-ray beams (30 kVp, 100 kVp and 100 kVp with gold, gadolinium, lead or tungsten filtration) were investigated for their preferential absorption qualities by IUdR sensitized DNA. The 30 kVp, 100 kVp and 100 kVp with tungsten filtration were then used to irradiate CHO cells, with or without IUdR incorporation (i.e. 10(-5) M of IUdR for 3 days). Radiation absorption calculations were performed to determine the increase in energy absorption in DNA with and without IUdR incorporated. In order to measure the in vitro biological effects of K-edge absorption, cell survival experiments were performed. The radiation physics calculations yielded an iodine dose enhancement ratio (DER) of 1.4+/-0.15. 1.8+/-0.15 and 2.7+/-0.15 for the 30 kVp, 100 kVp and tungsten filtered 100 kVp respectively, for 18% IUdR replacement of thymidine in DNA. The corresponding cell sensitization enhancement ratios (SER), determined from the cell survival assay, were determined to be 1.24+/-0.2, 1.8+/-0.2 and 2.3+/-0.3 for the 30 kVp, 100 kVp and tungsten filtered 100 kVp respectively, for cells with 18+/-2% IUdR incorporation. These SER values are in reasonable agreement with the DER values of 1.4, 1.8 and 2.7. From these radiation calculations and radiobiology experiments we confirm that using x-radiation energies above the K-edge of iodine (33.2 keV) can have a significant effect on cell survival. This effect is due mainly to the increase in the local dose to the DNA for IUdR-sensitized cells compared with the normal DNA which lacks the iodine contrast agent. Our results support the clinical application of IUdR and low-energy brachytherapy, perhaps using new technologies such as the x-ray needle or new isotopes such as Yb-169.

Molecular evidence for the expression of Schwann cell markers in human neuroblastoma

Human neuroblastoma (NB) cell lines have been suggested to represent a model of neural crest differentiation. The expression of several Schwann-cell-associated antigens was examined by flow cytometry and Northern blot analysis. Variable reactivity of the human NB cell lines was found in both the level and pattern of reactivity. Retinoic acid treatment of cell line SMS-KAN resulted in a neuron-like morphological differentiation and a decrease in several of the glial markers under study. Similarly, Northern blot analysis illustrated myelin-associated glycoprotein expression, and decreased expression of this message with retinoic acid treatment was consistent with the neuron-like morphological changes. Overall, human NB in vitro was found to be multipotential, but we have shown that it is capable of expressing several Schwann cell markers which are modulated during induced differentiation.

Induced morphological changes in human small cell lung carcinoma cells

Several theories suggest that lung carcinomas are not totally separate entities, but are derived from a common precursor, probably of endodermal origin. The histological classification of lung cancers is complex, with much overlap between groups broadly designated as small cell (SCLC), squamous cell, adenocarcinoma and all others simply termed non-small cell. It is shown here that in vitro exposure of classic, non-adherent SCLC lines to 10 microM 5' bromodeoxyuridine (BrdU) results in a rapid cell-line dependent change to a morphology consistent with an adherent, non-small cell phenotype. Accompanying this morphological shift is a decreased expression of the amplified N-myc protooncogene. These induced changes underline the morphological relatedness of lung carcinoma cell lines.

Human melanoma-associated antigen expression on human neuroblastoma cells: effects of differentiation inducers

We have described two human melanoma-associated antigens (HMAA), recognized by the murine monoclonal antibodies LS62 and LS109. LS62 recognizes the neuroglandular antigen (NGA), which is overexpressed in neoplastic melanocytes as well as in several tissues of neuroectodermal origin. These antibodies were used to screen six neuroblastoma cell lines and one neuroepithelioma cell line. A melanoma cell line, G361, known to express the two antigens, was used as the positive control. Variable expression of the two antigens was detected in neuroblastoma cells. The surface expression of NGA and of the LS109 antigen was modulated in parallel with the morphological differentiation induced by retinoic acid, 5-bromodeoxyuridine, or cyclic AMP analog/activators. The modulation of the expression of the two HMAA was detected in G361 melanoma cells and in one of the neuroblastoma cell lines, SK-N-SH. These results suggest altered expression of both antigens during melanoma and neuroblastoma cell differentiation in culture.

Effects of retinoic acid and bromodeoxyuridine on human melanoma-associated antigen expression in small cell lung carcinoma cells

The dispersed neuroendocrine system includes cells with different embryological derivations, sharing a common neuroendocrine (NE) program, as indicated by the expression of NE markers, some of which are shared antigenic determinants. We report here that the small cell lung carcinoma cells NCI-H69 express the two human melanoma-associated antigens (HMAA) NGA/LS62 an LS109. Incubation of NCI-H69 cells with maturational inducers, such as retinoic acid and bromodeoxyuridine (BrdU), upregulated the expression of both HMAA. Exposure to BrdU for 4 weeks induced the appearance of a different phenotype in subpopulations of NCI-H69 cells, which became epithelioid, substrate-adherent, grew in monolayer and continued to express NE-associated antigens in variable amount. The shift in phenotype was not reversible after BrdU withdrawal and was maintained for at least 6 months in continuous culture. The substrate adhesion of NCI-H69 cells was paralleled by a change in NGA glycosylation pattern, thus suggesting a possible functional role for NGA in cell substrate adhesion/recognition.

Melanocytic differentiation of human neuroblastoma: expression of a human melanosome-associated antigen

Five human neuroblastoma cell lines were examined for expression of a human melanosome-associated antigen (HMSA). Only cell line SK-N-SH reacted with a monoclonal antibody, HMSA-2, shown to recognize melanosomal glycoproteins. To further characterize the melanocytic lineages of SK-N-SH, three morphologically distinct clones designated SK-N-SH-N (neuroblast type), SK-N-SH-F (fibroblast type), and SK-N-SH-EP (epithelial type) were established by colony formation cloning. By fluorescence-activated cell sorter analysis and tyrosinase assay, we found that only SK-N-SH-EP and SK-N-SH-F reacted with HMSA-2 and had tyrosinase activity. These results suggest that epithelial-type and fibroblast-type cells appear to possess the melanocytic potential, but not neuroblast-type cells. Furthermore, SK-N-SH-EP was found to spontaneously convert to neuroblast-type or fibroblast-type cells, whereas SK-N-SH-N and SK-N-SH-F clones have remained morphologically stable. Our results suggest that at least one neuroblastoma cell line, SK-N-SH, may be an excellent model for investigating clonal maturation and the melanocytic differentiation of neuroblastoma.

Alterations in plasminogen activator and inhibitor activity during the differentiation of a human neuroblastoma cell line, SMS-KAN

The fibrinolytic enzyme profile of SMS-KAN human neuroblastoma cells was found to vary dramatically during the differentiation process. Five maturational agents--retinoic acid, dibutyryl cAMP, 5-bromodeoxyuridine, sodium butyrate and phorbol myristate acetate were tested for their effects on cellular morphology, DNA synthesis, plasminogen activator (PA) and PA inhibitor (PAI) activity. SMS-KAN cells secrete urokinase (UK) and tissue PA (tPA) as well as a possibly unique PAI. Treatment of cells with 1 microM RA resulted in an inhibition of proliferation, extension of neurite-like processes indicative of differentiation, as well as a switch from secretion of UK to tPA and a reduction in PAI secretion. Other agents which caused neural process formation and decreased cell proliferation also induced alterations in PA/PAI while agents which had no detectable effect on cell growth induced little change in the fibrinolytic enzyme profile.

Effect of retinoic acid on human neuroblastoma: correlation between morphological differentiation and changes in plasminogen activator and inhibitor activity

The relationship between plasminogen activator (PA)/plasminogen activator inhibitor (PAI) activity and morphological differentiation was investigated in human neuroblastoma (NB) cells treated with retinoic acid (RA). Conditioned medium from nine NB cell lines and one closely related neuroepithelioma line was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and zymography. All NB cell lines were shown to secrete urokinase (UK)-type PA (mol. wt., 52 kDa), and all except two produced tissue PA (mol. wt., 65 kDa). Identification of the PAs was made based on molecular weight and sensitivity to inhibition by anti-UK and anti-tPA antibodies. Several cell lines expressed PA inhibitory molecules; two molecular-weight forms were observed (35 and 40 kDa) in different cell lines. Complex formation with [125]I-labelled proteases revealed specific binding with UK and trypsin but not thrombin, plasmin, or kallikrein. After treatment for 6 days with 1 microM RA, six of the cell lines exhibited an increase in cell-associated and/or secreted tPA activity, corresponding to morphological differentiation of the cells as manifested by extensive neurite outgrowth. A decrease in UK and UK-complex secretion was observed in several of these cell lines. Three cell lines exhibiting no detectable morphological alterations with RA treatment also showed no dramatic changes in PA/PAI activity. These results suggest that morphological differentiation of NB cells may be associated with alterations in the regulation of PA activity.

Recognition of an in vivo immune response to human neuroblastoma modulation of antigen expression by retinoic acid

Neuroblastoma is one of the most common solid tumors of childhood and is notable for its ability to spontaneously regress and, in some instances, to differentiate to less malignant ganglioneuromas. Since immune mechanisms may account for these phenomena, identification of in vivo immune responses to tumor cell surface antigens may be important to the progression of the disease. As determined by analysis on the fluorescence-activated cell sorter, sera from 10 of 18 neuroblastomas patients were found to contain antibodies to a cell surface antigen present on subpopulations of cells from human neuroblastoma cell lines maintained in vitro. Eight human neuroblastoma cell lines were examined and found to vary in reactivity with sera. Induction of differentiation of cell lines with retinoic acid (RA) in vitro resulted in most cell lines bearing higher percentages of positive cells but with a decreased mean cell fluorescence. Preliminary Western blot analysis of lysates of the human cell lines NMB/N7, SMS-KAN, and SK-N-MC showed two principal antigen bands on reducing gels. Comparison of sera from different individuals on lysates of cell lines showed reactivity principally with bands of 105-110 kD and 65-70 kD and an additional minor band of slightly lower molecular weight with the higher titer sera. The ability of different sera to recognize a common antigen pattern suggests that this represents an immunodominant cell surface antigen. Examination of reactivity of other cell lines in this system showed that positive sera reacted with all neuroblastoma lines examined, one neuroepithelioma (SK-N-MC), two melanoma lines (MeWo, G361), and one adrenal-derived adenocarcinoma (SW-13).

Expression of markers shared between human natural killer cells and neuroblastoma lines

Neuroblastoma is a tumor of neuroectodermal origin arising most commonly from the adrenal medulla. We have examined the ability of several monoclonal antibodies which recognize markers predominantly expressed on human natural killer (NK) cells to react with neuroblastoma cell lines in vivo derived sections of tumor. HNK-1 (Leu 7) is a monoclonal IgM antibody which recognizes a carbohydrate epitope on NK cells and a wide range of tumor cell types. We have shown that HNK-1 recognizes the human neuroblastoma lines SMS-KCNR, SMS-KAN, NMB/N7, and IMR/5. Expression of this antigen on cell lines can be slightly increased by retinoic acid-induced differentiation of the cells. N901 (NKH1), a monoclonal antibody raised against interleukin 2-dependent human NK cell lines also recognizes all human neuroblastoma cell lines examined. This expression is independent of differentiation induction and levels remain unaltered following retinoic acid treatment of the cell lines. Lastly, with monoclonal antibody 49H.8, it has been found that reactivity of the lines is weak until induction of differentiation, after which highly significant increases of reactivity are seen. 49H.8 recognizes several cryptic carbohydrate antigens with varying affinities, shown to identify mouse and rat NK cells. In contrast to other NK markers, human neuroblastoma cell lines did not express significant reactivity with B73.1, Leu 11b, or Leu 18. Immunohistochemical staining of sections of human neuroblastoma tumors correlated with the in vitro findings; however, staining with N901 and 49H.8 was only seen on frozen sections, not paraffin-embedded. The significance of shared NK cell-neuroblastoma/neuron antigens is currently under investigation.

The characterization and cellular distribution of a family of antigens related to myelin associated glycoprotein in the developing nervous system

The antigenic epitope detected on myelin associated glycoprotein (MAG) by the monoclonal antibody HNK-1 (Leu 7) was sensitive to degradation by trifluoromethane-sulfonic acid (TFMS) and is therefore probably carbohydrate in nature. This antigen was found to be widely distributed within the rat and chicken embryonic nervous system and was present on cultured central and peripheral neurons (100%), oligodendrocytes (100%) and astrocytes (70-80%) as detected by double marker immunofluorescence. The antigen could be removed from cultured neurons by trypsinization and its resynthesis was blocked by cycloheximide, suggesting that the carbohydrate epitope detected by HNK-1 was attached to a de novo synthesized protein. Several molecular species were detected on Western blots of detergent extracts from 13-15d rat embryonic brain and neuron-enriched cultures from chick spinal cord and dorsal root ganglia. Protein components with molecular weights in the ranges of 90-100 kd to 280 kd were observed and comprise a family of glycoproteins containing the HNK-1 reactive carbohydrate epitope present on MAG. These glycoproteins could play a role in intercellular interactions within the developing nervous system.

Differential expression of the Leu-7 antigen on human lung tumor cells

The HNK-1 monoclonal antibody detects an antigen (Leu-7) on a subpopulation of large granular lymphocytes which have natural killer cell function. Recently this antigen has been found on nonhemopoietic tissues. In the present study human lung tumor cells were examined for the presence of Leu-7 antigen using an enzyme-linked immunosorbent assay, immunoperoxidase staining, and fluorescence-activated cell sorter analysis. All small cell lung tumor cells tested were Leu-7 positive. In contrast only two of seven biopsy specimens from small cell lung cancer patients were Leu-7 positive. Several large cell lung tumor lines were Leu-7 positive while an adenocarcinoma and squamous cell carcinoma were negative. These results indicate that expression of Leu-7 antigen on lung tumor cells is heterogeneous both in vitro and in vivo. Small cell lung tumor lines have been reported to undergo histological conversion in vitro accompanied by the loss of a number of biochemical markers. In our study histologically converted cells exhibited much less reactivity with HNK-1 than did the parent cells. These results indicate that the degree of expression of Leu-7 antigen may be under the control of differentiation-related events. Thus monoclonal antibody HNK-1 has been very useful in studying heterogeneity within and among lung tumor cells.

Accelerated regenerative neurite formation by a neuronal surface epitope reactive with the monoclonal antibody, Leu 7

A family of glycoproteins sharing an epitope with myelin associated glycoprotein as recognized by the monoclonal antibody Leu 7 (HNK-1) has been found to be present on neurons grown in culture from embryonic chicks and rats. Immunofluorescent staining demonstrates that, in vitro, 100% of the neurons from dorsal root ganglia and spinal cord from 7-8 day chick embryos react with Leu 7. Analysis of in vitro regenerative neurite formation by neurons on substrates enriched with Leu 7 showed accelerated regenerative process formation under limiting conditions. These results indicate that the Leu 7 epitope on neurons is appropriate for substrate adhesion and promotes rapid process extension.

The cooperative effect of the satin and beige mutations in the suppression of NK and CTL activities in mice

The functional activity of natural killer (NK) cells has been found to be modulated by several point mutations associated with coat color. The most commonly studied gene, beige (Bg), has been found to block a postrecognition event in the lytic cycle. Four other coat color mutations in the mouse (satin, leaden, fuzzy, pale ears) were studied for their effect on NK cell function, and only one, satin (Sa), was found to be suppressive. When both the Sa and Bg mutations were present in the same animal, their effects were synergistic in the suppression of NK levels. Normal numbers of NK cells were present in these double mutants, as determined by the frequency of IgG2b binding cells and by antiasialo GM1 staining. The ability of Sa/Bg NK cells to recognize and bind targets suggests that the defect is localized in the postbinding cytolytic pathway. These genes were not specific for NK cells and also suppressed alloimmune cytolytic T lymphocyte function. Since Sa/Bg mice are much more suppressed in NK function than Bg mice, we suggest that this double mutant may be a better model for NK deficiency in vivo.

Recognition of myelin-associated glycoprotein by the monoclonal antibody HNK-1

Myelin-associated glycoprotein (MAG) is a quantitatively minor component in both peripheral and central myelin sheaths that is thought to have a role in cell-cell interactions within the nervous system. We show here that a mouse monoclonal antibody, HNK-1, which is directed against human natural killer cells also recognizes an antigenic determinant of human central and peripheral nervous system white matter by immunoperoxidase staining of tissue sections. Immunoblot analysis of myelin proteins and purified extracted MAG indicates that the antigen recognized is MAG.

The immunoregulatory role of bone marrow. III. Further characterization of the suppressor cell and its mode of action

In vitro primary antibody responses of spleen cells can be suppressed in a dose-dependent manner by the addition of bond marrow cells (BMC). This suppression was not abrogated by treatment of BMC with anti-Thy 1, anti-Lyt nor with anti-I-J antisera and complement. Furthermore, preculture of BMC with the synthetic thymic pentapeptide (TP5) or Soluble Thymic Factor (STF) before anti-Thy-1 treatment was similarly ineffective in removing the suppressor cell activity. Similarly, treatment of BMC with polyvalent anti-immunoglobulin serum or anti-Ia antiserum and complement failed to remove the suppressor activity. However, preparations of anti-H-2 and anti-stem-cell antisera were capable of significantly decreasing the suppressive ability of BMC. BMC were also shown to be capable of suppressing antibody responses induced by the polyclonal activators dextran sulphate (DxS), lipopolysaccharide (LPS) and purified protein derivative from tubercle bacilli (PPD). The non-specificity of this suppressor coupled with the absence of well-defined antigen on its surface may suggest that this cell represents a basic level of immune regulation.