Infiltration of dendritic cells in relation to tumor invasion and lymph node metastasis in human gastric cancer

The infiltration of dendritic cells determined in 210 patients with gastric carcinoma was investigated from the standpoint of tumor invasion, lymph node metastasis, and prognosis. Dendritic cell infiltration was graded as "slight" and "marked." The 39% frequency in the marked infiltration group at the mucosal stage did not change in proportion to invasion into the deeper layers. The 5-year survival rate was 60.4% in patients with marked infiltration and 38.8% in those with slight infiltration, which was statistically different (P less than 0.01). The difference in survival rates was only statistically significant in those with cancer emerging from the serosa (P less than 0.001). There was a similar incidence of lymph node metastasis between the marked and slight infiltration groups in each grade of tumor invasion. However, marked infiltration of dendritic cells prevented widespread nodal involvement beyond the primary node in cases of advanced carcinoma (P less than 0.05). These findings indicate that infiltrating dendritic cells do not prevent the spread of tumor invasion but do prevent nodal involvement; therefore, for patients with a gastric cancer emerging from the serosa, the prognosis will be good.     

Distribution of lymphocytes to tumor tissue and regional lymph nodes in patients with gastric cancer--the effects of oral administration of OK-432

We attempted to clarify the accumulation of radiolabeled lymphocytes to tumors and regional lymph nodes in patients with gastric carcinoma. The effects of oral administration of OK-432 were also studied. Five patients with gastric cancer and one who underwent endoscopic mucosal resection, were entered in the study. Prior to the tracer study in 3 patients with gastric cancer, 5 KE of OK-432 was administered for 2 days. Peripheral mononuclear cells were separated and labeled with [111] In-tropolone. After the resection of stomach, tumor tissue, normal gastric mucosa, regional lymph nodes, and non-regional lymph nodes were dissected and radioactivity was measured by a gamma-counter. Accumulation of lymphocytes to the tumor tissue and n1 lymph node station was more than two times that in the normal gastric mucosa and ten times that in non-regional lymph nodes. Accumulation of lymphocytes to the n2 station was strongly enhanced by oral administration of OK-432.     

Prognostic value of tumor-infiltrating dendritic cells in colorectal cancer: role of maturation status and intratumoral localization.

The clinical significance of tumor-infiltrating dendritic cells has been reported in a variety of human solid tumors as shown by the correlations found between the presence of tumor-infiltrating dendritic cells and clinical prognosis. In this study, we evaluated whether there is an association between the presence and maturation status of tumor-infiltrating dendritic cells, T lymphocytes, and clinical course in 104 primary tumor samples of patients with colorectal cancer. Dendritic cells were identified with four different markers (S-100, HLA class II, CD208, and CD1a) in double immunohistochemistry, with laminin as second marker to support the exact localization. Tumor-infiltrating dendritic cells showed a distinct infiltration pattern based on their maturation status. CD1a-positive dendritic cells resided in the advancing tumor margins in relatively high numbers, whereas mature CD208-positive dendritic cells were sparsely present in the tumor epithelium but mainly distributed in the tumor stroma and advancing tumor margin. Furthermore, high infiltration of CD1a-positive dendritic cells in the tumor epithelium was significantly correlated to the infiltration of CD4 lymphocytes (P = 0.006). Patients with relatively high numbers of mature CD208-positive infiltrating dendritic cells in the tumor epithelium had a shorter overall survival (P = 0.004). In addition, patients with relatively high numbers of CD1a-positive dendritic cells in the advancing margin of the tumor had a shorter disease-free survival (P = 0.03). We found that tumor-infiltrating dendritic cells had preferential infiltration sites within a tumor, affected local tumor cell-immune cell interactions, and correlated to the clinical prognosis of colorectal cancer patients.     

Expression of chemokine receptor CCR7 is associated with lymph node metastasis of gastric carcinoma

The interactions of chemokine receptor CCR7 and its ligands are essential for migration of lymphocytes and dendritic cells to lymph nodes. In this study, we found that 4 of 6 (67%) gastric carcinoma cell lines tested expressed functional CCR7 for the chemokine CCL21/6Ckine, as demonstrated by calcium mobilization and actin polymerization assays. Moreover, we also showed that signaling through CCR7 induced chemotactic and invasive responses in CCR7-positive gastric carcinoma cells. In clinical samples, immunohistochemical assay showed that CCR7-positive carcinoma cells were detected in 42 of 64 (66%) cases and a significant difference in both lymph node metastasis (P < 0.001) and lymphatic invasion (P < 0.001) between CCR7-positive and -negative cases. Patients with CCR7-positive tumors had a significantly poorer prognosis than those with CCR7-negative tumors (P < 0.05). Stepwise regression analysis revealed that the most important factor related to lymph node metastasis was the expression of CCR7. These results indicated that CCR7 and its ligands interaction is associated with preferential lymph node metastasis of gastric carcinoma.     

727例胃癌根治术标本淋巴结精细分拣的临床价值探讨

  目的  探讨胃癌根治术标本中淋巴结精细分拣的临床应用价值。  方法  回顾性分析2016年1月至2017年12月就诊于天津医科大学肿瘤医院实施胃癌根治术的727例胃癌患者临床病理资料，按照手术切除标本中淋巴结分拣方式分为精细淋巴结分拣组和区域淋巴结分拣组，分析两组患者送检淋巴结数目、转移淋巴结数目的差异并进行相关性分析比较。  结果  两组患者的性别、年龄、肿瘤大小等因素间差异均无统计学意义（P > 0.05），两组之间具有可比性。精细淋巴结分拣组患者淋巴结送检数目明显多于区域淋巴结分拣组（P < 0.001）。在T分期、N分期以及TNM分期相同的情况下，精细淋巴结分拣组送检淋巴结数目显著多于区域淋巴结分拣组（P < 0.001）；精细淋巴结分拣组淋巴结转移数目也显著多于区域淋巴结分拣组（P < 0.001）。此外，两组患者送检淋巴结数目与转移淋巴结数目均呈正相关，差异具有统计学意义（精细淋巴结分拣组r=0.181，P=0.023；区域淋巴结分拣组r= 0.227，P < 0.001），且精细淋巴结分拣组患者的送检淋巴结数目与转移淋巴结数目之间相关性弱于区域淋巴结分拣组患者。  结论  胃癌根治术后精细淋巴结分拣可以提高送检淋巴结数目，提供精确的术后淋巴结分期，减少分期迁移，可以在临床上规范性推广。      

Lymph node metastasis and relation to tumour growth potential and local immune response in advanced gastric cancer

To evaluate the relation between the degree of lymph node metastasis and the growth potential of tumour cells and the local immune function in gastric cancer, we analyzed data on 444 patients with advanced serosally invasive gastric cancer who underwent curative gastrectomy. Tumour growth potential was evaluated based on the value proliferating cell nuclear antigen (PCNA) in the primary tumour, and dendritic cell infiltration into the tumour was determined as an indicator of local immune function. The values of PCNA labeling in the primary tumour increased and the infiltration of dendritic cells into the tumour decreased in relation to the extent of lymph node metastasis. High growth potential and low immune function were seen in cases with n3 lymph node metastasis. There was a reverse relation between the PCNA labeling index and dendritic cell infiltration. A variety of forms of recurrence was noted in patients with lymph node metastasis while the prognosis was less favorable, in relation to the degree of lymph node metastasis. Thus, the potential for nodal spread appears to be associated with the growth potential of tumour cells and with the local immune status of the tumour. Int. J. Cancer 74:224-228, 1997. © 1997 Wiley-Liss Inc.     

Prognostic significance of tumor-host interaction in clinical gastric cancer: Relationship between dna ploidy and dendritic cell infiltration

DNA ploidy of tumor cells and the degree of infiltration of dendritic cells were determined in 93 gastric cancer tissue specimens, and the mechanisms of tumor-host interaction on the prognosis were investigated. DNA ploidy patterns were grouped into low and high ploidy, and the degree of infiltration of dendritic cells (DC) was graded into marked and slight infiltration. In the low ploidy group, the 5-year survival rates in patients with marked and slight DC infiltration were 80.7% and 61.5%, respectively (P < 0.05). In the high ploidy group, however, there were no significant differences. In cases of low ploidy, the incidence of lymph node metastasis was significantly lower in the marked DC infiltration group compared with findings in the slight DC group. Thus, markedly infiltrating dendritic cells in gastric cancer tissue may lead to prolongation of survival time for patients with a carcinoma of the low ploidy profile, by preventing widespread nodal involvement. © 1993 Wiley-Liss, Inc.     

MIB-1, p53, bcl-2, and WAF-1 expression in pelvic lymph nodes and primary tumors in early stage cervical carcinomas: correlation with clinical outcome

A complete series of 40 cervical carcinomas with pelvic lymph node metastases were analysed immunohistochemically for prognostic markers. The aims of this study were to examine whether the detection of MIB-1, p53, bcl-2, and WAF-1 could be used as a prognostic marker for tumor recurrence and survival rate. During the period of observation (mean 222, range 72-360 months) 22 (55%) recurrences were encountered and 20 patients died of the disease. There were 35 squamous cell carcinomas (87.5%), 2 adenosquamous carcinomas (5.0%), and 3 pure adenocarcinomas (7.5%). One tumor (2.5%) was well differentiated, 12 tumors (30%) were moderately differentiated, and 27 tumors (67.5%) were poorly differentiated. The primary tumor grade (P=0.037) and radicality of the surgical margins (P=0.021) were significant prognostic factors with regard to tumor recurrence. The site and number of lymph nodes with metastases had no prognostic value. P53, bcl-2, and WAF-1 were not predictive factors for recurrences or the cancer-specific survival rate. The concordant expression of WAF-1 in the primary tumor and in lymph node metastases was lower than for p53 and bcl-2. The proliferative activity (MIB-1) seemed to be lower in tumor cells metastasized to the pelvic lymph nodes than in cells of the primary tumor. Expression of MIB-1 in lymph nodes was predictive of disease-free survival in both univariate and multivariate proportional hazard Cox analyses.     

Decrease in ICAM-1 expression on gastric cancer cells is correlated with lymph node metastasis

Background. Lymph node metastasis is a frequent type of metastasis in patients with gastric cancer. The mechanisms responsible for this type of metastasis, however, are not clearly understood. We hypothesize that the immunosurveillance system between cancer cells and lymphocytes may be associated with the lymph node metastatic process. In this study, we examined the correlation between lymph node metastasis and intercellular adhesion molecule-1 (ICAM-1), which mediates the immunosurveillance system between tumor cells and cytotoxic lymphocytes, in gastric cancer. Methods. One hundred and forty-three specimens resected from patients with gastric cancer were investigated by staining with a monoclonal antibody against ICAM-1. We studied the correlation between the expression of ICAM-1 and various clinicopathologic factors, as well as infiltration of tumor-infiltrating lymphocytes (TILs). Results. ICAM-1 expression on gastric cancer cells was significantly decreased in patients with lymph node metastasis. The infiltration of TILs was associated with ICAM-1 expression level. The prognosis of patients with ICAM-1-negative tumors was poorer than the prognosis of those with ICAM-1-positive tumors. Conclusions. These findings suggest that ICAM-1 expression on cancer cells is closely associated with lymph node metastasis in gastric cancer, under the influence of the host immunosurveillance system. Received on Aug. 20, 1999; accepted on Jan. 5, 2000     

Infiltration of dendritic cells and NK cells into the sentinel lymph node in oral cavity cancer

The sentinel lymph node (SLN) is regarded as the first tumor-draining lymph node, which may be the initial site activated by tumor antigens. To clarify the immunological functions of SLNs, a total of 89 tumor-free regional lymph nodes (41 SLNs and 48 non-SLNs) were obtained from 12 patients with oral cavity cancer, and infiltration of both DCs and NK cells was determined by immunohistochemistry. S-100+ and CD1a+ DCs infiltrated significantly into SLNs compared to non-SLNs. Analysis in each of the pN0 and pN+ patients showed that all the DC markers in pN0 patients and only S-100+ in pN+ patients were significantly more abundant in SLNs. Moreover, infiltration of CD83+ DCs was less in pN+ patients than in pN0 patients. These results suggest that more significant immune responses against cancer occur in SLNs than in non-SLNs. However the progression of disease including nodal disease may cause systemic immunosuppression.     

Intratumoral recombinant human interleukin-12 administration in head and neck squamous cell carcinoma patients modifies locoregional lymph node architecture and induces natural killer cell infiltration in the primary tumor.

The objective of this study was to evaluate the histologic and immunohistopathologic effects of intratumorally given recombinant human interleukin-12 on the immune cells in the primary tumors and regional lymph nodes. Ten previously untreated patients with head and neck squamous cell carcinoma (HNSCC) were injected in the primary tumor twice to thrice, once weekly, at two dose levels of 100 or 300 ng/kg, before surgery. These patients were compared with 20 non-IL-12-treated control HNSCC patients. In the primary tumor, the number of CD56+ natural killer (NK) cells was increased in IL-12-treated patients compared with control patients. In some IL-12-treated patients, an impressive peritumoral invasion of CD20+ B cells was noticed. No differences were seen in the CD8+ or CD4+ T lymphocytes. Interestingly, major differences were apparent in the architecture of the enlarged lymph nodes of IL-12-treated patients; in particular, the distribution of B cells differed and fewer primary and secondary follicles with smaller germinal centers were observed. In addition, a decrease of dendritic cell lysosyme-associated membrane glycoprotein-positive cells in the paracortex was noted, resulting in a reduction of paracortical hyperplasia. In the lymph nodes, especially the CD56+ NK cells but also the CD8+ and CD4+ T lymphocytes, produced a high amount of IFN-gamma. Patients, irrespectively of IL-12 treatment, with a high number of CD56+ cells in the primary tumor had a better overall survival than those with a low number. In conclusion, after i.t. IL-12 treatment in HNSCC patients, the largest effect was seen on the NK cells, with a higher number in the primary tumor and a high IFN-gamma mRNA expression in the lymph nodes. Significant effects were noted on B cells, with altered lymph node architecture in every IL-12-treated patient and excessive peritumoral infiltration in some patients.     

进展期胃癌腹主动脉旁淋巴结清扫术研究

目的 探讨进展期胃癌患者施行腹主动脉旁淋巴结（N16）清扫手术的必要性及手术适应证。方法 通过对36例进展期胃癌患者行腹主动脉旁淋巴结（N16）清扫术，分析影响腹主动脉旁淋巴结转移的临床病理因素，并与同期进行的D2手术50例进行手术创伤程度、并发症及术后生活质量比较。结果 腹主动脉旁淋巴结出现转移与肿瘤浸润深度、组织学类型及其他各组淋巴在T3，T4及低分化腺癌的进展期胃癌患者，腹主动脉旁淋巴结应纳入清扫范围之内。     

Prognostic value of intratumoral natural killer cells in gastric carcinoma

BACKGROUND: Natural killer (NK) cells are a group of effector cells that act nonspecifically against tumor cells. The correlation between intratumoral NK cell infiltration and clinicopathologic features remains unclear. METHODS: The authors selected 146 patients with gastric carcinoma who underwent gastrectomy at Kagoshima University Hospital between 1985-1995. Immunohistochemical staining with the CD57 antibody was performed for the evaluation of NK cell infiltration. A total of 25 areas containing CD57 positive cells were selected and the number of NK cells were counted (magnification, x200). The patients were divided into 2 groups: patients with a high level of NK infiltration (n = 39) (>25 NK cells/25 high-power fields [HPF]) and patients with a low level of NK infiltration (n = 107) (<25 NK cells/25 HPF). Intratumoral lymphocytic infiltration also was counted in 25 areas at a magnification of x200. Patients were classified into a high infiltrating lymphocyte (IL) group (n = 69) (>150 cells/HPF) and a low IL group (n = 77) (<150 cells/HPF). The Kaplan-Meier curve was used to analyze surgical outcome. Multivariate analyses were performed to evaluate prognostic factors. RESULTS: Patients with a high level of NK infiltration had a higher rate of early gastric carcinoma, fewer metastases to the lymph nodes (P < 0.01), and less lymphatic invasion (P < 0.05) than patients with a low level of NK infiltration. NK cell infiltration also was found to correlate with depth of invasion, clinical stage, and venous invasion. There was no correlation between NK cells and lymphocytic infiltration (P = 0.07; correlation coefficient = 0.15). The 5-year survival rate of patients with a high rate of NK infiltration was 78%, which was significantly better than that of patients with a low level of NK infiltration (P < 0.01). Multivariate analysis did not show NK cell infiltration to be a significant prognostic factor. Combination analysis of the number of NK cells and lymphocytic infiltration was shown to be an independent prognostic factor (P = 0.02; hazard ratio = 1.32). CONCLUSIONS: Patients with a high level of NK infiltration were found to have a better prognosis than those with a low level of NK infiltration. Combination analysis with lymphocytic infiltration may provide useful information regarding the immunologic condition of patients with gastric carcinoma.     

Antitumor Effector Mechanism at a Distant Site in the Double Grafted Tumor System of PSK, a Protein-bound Polysaccharide Preparation

The antitumor effect at a distant site of PSK, a Coriolus preparation, was analyzed with the double grafted tumor system in which BALB/c mice received simultaneous intradermal inoculations of Meth-A tumor in the right (10⁶ cells) and left (2 × 10⁵ cells) flanks and were then injected with PSK in the right-flank tumor on day 3. PSK inhibited the growth of not only the right but also the left (non-treated) tumor. Immunized spleen cells were taken from mice which had been cured by the intratumoral administration of 5 mg of PSK and were injected into the Meth-A tumor on day 3. Adoptive transfer of PSK immunized spleen cells caused the complete regression of Meth-A tumors. The effector cell activity was lost only after treatment with anti-Lyt-1 monoclonal antibody plus complement. Spleen cells and right and left regional lymph node cells prepared from PSK immunized mice were examined for Thy-1, Lyt-1, Lyt-2 and asialo GM1 phenotypes. The number of Lyt-1-positive lymphocytes increased in the right regional lymph nodes after intratumoral administration of PSK. A massive accumulation of macrophages and polymorphonuclear leukocytes was found in the right tumor and an infiltration of macrophages and Lyt-2-positive lymphocytes was found in the left (non-treated) tumor by immunohistochemical analyses. These results suggest that intratumoral administration of PSK induces Lyt-1-positive cells first in regional lymph nodes, then in the spleen, and subsequently induces macrophages and Lyt-2-positive cells in the left (non-treated) tumor, thus bringing about the regression of metastatic tumors.     

Further evidence that altered p16/CDKN2 gene expression is associated with lymph node metastasis in squamous cell carcinoma of the esophagus

Esophageal squamous cell carcinoma (ESCC) has high malignant potential with a poor outcome. Lymph node metastasis is the most useful indicator for predicting the outcome of ESCC. The p16/MTS1/CDKN2 gene and the cyclin D1/PRAD-1 gene cooperatively regulate CDK4-mediated phosphorylation of RB protein in the cell cycle. We immunohistochemically detected p16, cyclin D1, and RB expressions in both primary lesions and metastatic lymph nodes in ESCC. Among the 50 ESCC primary lesions, 24 (48%) were positive for p16, while 26 (52%) were negative for p16. Sixteen (32%) were p16-positive, 34 (68%) were p16-negative among the 50 ESCC metastatic lymph nodes. Eight cases (16%) were p16-positive in primary lesion and p16-negative in lymph node, however, no cases that was p16-negative in the primary tumor exhibited p16-positivity in metastatic lymph nodes (p < 0.0001). Seventeen (34%) of the 50 ESCC primary lesions were cyclin D1-positive, while 33 (66%) were cyclin D1-negative. Twenty-four (48%) were cyclin D1-positive, 26 (52%) were cyclin D1-negative among the 50 metastatic lymph nodes. Five cases (10%) were cyclin D1-positive in primary lesion and cyclin D1-negative in lymph node, and 12 cases (24%) were cyclin D1-negative in primary lesion and cyclin D1-positive in lymph nodes. Nine cases (18%) were RB-negative in 50 primary lesions, and the rate of loss of RB expression in metastatic lymph nodes was not markedly higher than in primary lesions. Thirty-nine (78%) of 50 primary lesions and 46 (92%) of 50 metastatic lymph nodes had altered expression of at least one of the three G1 control genes. Tumor cell with disruption of these cell cycle regulators can get a growth advantage and metastatic potential during tumor progression, especially p16/CDKN2 alterations may be associated with lymph node metastasis in ESCC. These results also suggest that tumor cells in metastatic lymph nodes may have more aggressive proliferation and higher malignant potential than tumor cells in primary lesions.     

Prognostic value of extracapsular invasion and fibrotic focus in single lymph node metastasis of gastric cancer

BACKGROUND: Histological findings of metastatic lymph nodes are important prognosticators in patients with gastric cancer. The aim of this study was to clarify the clinical significance of various pathological characteristics of the early phase of lymph node metastasis in patients with gastric cancer, by selecting patients with tumors that had single lymph node metastases, no serosal invasion, and no metastases to the peritoneum, liver, or distant organs. METHODS: Seventy-eight patients were eligible and were entered in this study. These patients were subdivided according to the following histological characteristics of the one metastatic lymph node: size of the metastasis (i.e., amount of tumor cells [AT]), proliferating pattern (PP), intranodal location (IL), and the presence or absence of extracapsular invasion (ECI) and/or fibrotic focus (FF). Associations between clinicopathological factors, survival, and the nodal findings were examined. RESULTS: There were no correlations between AT or PP and any clinicopathological factors. IL was significantly correlated with venous invasion and the pathological characteristics of the primary tumor. ECI and FF were observed significantly more frequently in pT2 than in pT1 cancer. Overall survival (OS) differed significantly according to depth of invasion, venous invasion, and the presence or absence of ECI or FF, although OS was not affected by AT, PP, or IL. The 10-year overall survival rates of patients with and without ECI were 50% and 80%, respectively, while these rates for patients with and without FF were 50% and 79%, respectively. Multivariate analysis revealed that ECI and FF were significant prognosticators of survival. CONCLUSION: These results strongly suggested that the presence of ECI or FF could affect the survival of patients with gastric cancer.     

Significance of the lymph nodes in the 7th station in rational dissection for metastasis of distal gastric cancer with different T categories

Objective： To determine the clinicopathological characteristics, and evaluate the appropriate extent of lymph node dissection in distal gastric cancer patients with comparable T category. Methods： A retrospective study was conducted on 570 distal gastric cancer patients, who underwent gastric resection with D2 nodal dissection, which was performed by the same surgical team from January 1997 to January 2011. We compared the differences in lymph node metastasis rates and metastatic lymph node ratios between different T categories. Additionally, we investigated the impact of lymph node metastasis in the 7th station on survival rate of distal gastric cancer patients with the same TNM staging. Results： Among the 570 patients, the overall lymph node metastasis rate of advanced distal gastric cancer was 78.1%, and the metastatic lymph node ratio was 27%. The lymph node metastasis rate in the 7th station was similar to that of perigastric lymph nodes. There was no statistical significance in patients with the same TNM stage （stage Ⅱ and Ⅲ）, irrespective of the metastatic status in the 7th station. Conclusions： Our results suggest that to a certain extent, it is reasonable to include lymph nodes in the 7th station in the D 1 lymph node dissection.     

树突状细胞浸润对进展期胃癌生物学行为和预后的影响

目的　研究进展期胃癌组织中树突状细胞 (DCs)浸润与胃癌临床病理特征、生物学行为、预后之间的相关性 ,明确机体免疫因素对胃癌的影响。方法　用免疫组化 (SLAB)法检测 6 1例进展期胃癌术后组织标本中增殖细胞核抗原 (PCNA)以及DCs标志蛋白S 10 0的表达 ;以原位末端标记技术 (TUNEL)检测胃癌细胞凋亡比例。结果　有淋巴结转移的胃癌DCs浸润数量低于无淋巴结转移者 (P <0 .0 5 ) ;Ⅲ期胃癌DCs浸润数量低于Ⅰ、Ⅱ期胃癌 (P <0 .0 1)。高DCs浸润组的晚期胃癌比例低于低DCs组 (P <0 .0 5 ) ;高DCs浸润组预后好于低浸润组。DCs浸润与增殖细胞核抗原标记指数(PCNA LI)呈负线性相关 (r=- 0 .4 71,P <0 .0 1) ,与凋亡细胞指数 (AI)呈正线性相关 (r =0 .39,P <0 .0 1)。结论　DCs在胃癌的发展和预后中有重要作用 ,抑制胃癌细胞增殖、促进胃癌细胞凋亡是其可能的作用机制。     

The pattern of lymph node metastases in microsatellite unstable gastric cancer

Background

Microsatellite instability (MSI) is one of the new groups of molecular divisions of gastric cancer (GC). The aim of this study was to investigate the pattern of lymph node metastasis according to MSI status.

Cytokine-containing gelfoam implants at a postsurgical tumor excision site to stimulate local immune reactivity

We previously demonstrated increased numbers of CD34(+) progenitor cells in the peripheral blood of tumor bearers. Also demonstrated was the feasibility of chemoattracting these cells by sponge implants containing VEGF. The present study used a murine Lewis lung carcinoma (LLC) model to test if CD34(+) cells that are chemoattracted to a tumor excision site can be differentiated in situ into dendritic cells and whether this leads to increased local immune reactivity. After surgically excising established LLC tumors, mice received at the excision site gelatin sponge implants containing VEGF to chemoattract CD34(+) cells, and/or GM-CSF plus SCF to induce CD34(+) cell differentiation into dendritic cells. In some studies, lysates of GFP-transfected LLC cells (LLC(GFP)) were also included in the implants as a source of tumor antigen. After 2 weeks, implants and local lymph nodes were removed and analyzed. Implants containing VEGF, GM-CSF/SCF or VEGF/GM-CSF/SCF had a higher proportion of CD34(+) cells compared to control implants. However, the number of dendritic cells was higher in implants containing GM-CSF/SCF or VEGF/GM-CSF/SCF than those containing either VEGF or diluent. Regional lymph node from mice containing GM-CSF/SCF or VEGF/GM-CSF/SCF implants showed increased dendritic cell levels. However, when lysates from LLC(GFP) were added to the implants, the highest proportion of dendritic cells associated with GFP was in lymph nodes of mice containing GM-CSF/SCF implants. Lymph node cells from mice with GM-CSF/SCF or VEGF/GM-CSF/SCF had a higher level of proliferation and IFN-gamma secretion in response to in vitro LLC lysate challenge, with the greatest response being from lymph node cells of mice with GM-CSF/SCF implants. These results suggest the feasibility of using GM-CSF/SCF-containing implants to increase dendritic cell levels, uptake of tumor antigens, trafficking to lymph nodes and stimulation of immune reactivity at tumor excision sites with residual tumor.