Eosinophils and oral squamous cell carcinoma: a short review

Quantitative assessment of tumor-associated tissue eosinophilia and nuclear organizing region activity to validate the significance of the pattern of invasion in oral squamous cell carcinoma: A retrospective study

Introduction:

Pattern of invasion (POI) in scoring system of oral squamous cell carcinoma (OSCC) can predict local recurrence and overall survival rate. Argyrophilic nucleolar organizer region (AGNOR) counts are considered to reflect the biosynthetic and nucleolar activity of a cell and thus serve as an indicator of the rapidity of the cell cycle thereby indicating the proliferative index of the tumor. It is implied that higher tumor associated tissue eosinophilia (TATE) showed lesser venous invasion, lymph node metastasis and clinical recurrence. The aim of the study was to assess and evaluate the following criteria's: POI-1 to POI-4 as defined by Bryne et al. in OSCC, proliferative index by AgNOR stain and TATE with carbol chromotrope stain in OSCC, validity of POI by correlating the AgNOR proliferative index and TATE.

Materials and Methods:

Forty samples of formalin fixed paraffin embedded tissue blocks diagnosed of OSCC were taken for the study. Three sections were taken from a single block and then the tissues were stained differently with H & E Stain, AgNOR stain and Carbol chromotrope stain. First section stained with H & E was observed for POI and grading was done according to Bryne's criteria. The second and third sections were stained with AgNOR stain and Carbol chromotrope stain for proliferative index and TATE. One way analysis of variance was used to test the significance.

Results:

Mean AgNORs count increases gradually from type 1 to type 4, depicting the increase in the nucleolar proliferative index of the cells and was statistically significant. In the case of the mean eosinophilic count, type 1 shows the highest mean eosinophilic count and the count shows drastic decrease till type 3 and from type 3 to type 4 the decrease is more gradual and was statistically significant.

Conclusion:

The study validated that POI is a good predictor for prognosis and also can be included in grading OSCC along with routine histopathological criteria.

A new dawn for eosinophils in the tumour microenvironment

Eosinophils are evolutionarily conserved, pleotropic cells that display key effector functions in allergic diseases, such as asthma. Nonetheless, eosinophils infiltrate multiple tumours and are equipped to regulate tumour progression either directly by interacting with tumour cells or indirectly by shaping the tumour microenvironment (TME). Eosinophils can readily respond to diverse stimuli and are capable of synthesizing and secreting a large range of molecules, including unique granule proteins that can potentially kill tumour cells. Alternatively, they can secrete pro-angiogenic and matrix-remodelling soluble mediators that could promote tumour growth. Herein, we aim to comprehensively outline basic eosinophil biology that is directly related to their activity in the TME. We discuss the mechanisms of eosinophil homing to the TME and examine their diverse pro-tumorigenic and antitumorigenic functions. Finally, we present emerging data regarding eosinophils as predictive biomarkers and effector cells in immunotherapy, especially in response to immune checkpoint blockade therapy, and highlight outstanding questions for future basic and clinical cancer research.

Tumour-associated tissue eosinophilia (TATE) in oral squamous cell carcinoma: a comprehensive review

Oral squamous cell carcinoma is the most common head and neck malignancy, characterised by high invasive capacity, lymph node metastasis, and high recurrence rate. Among the morphological features of oral cancer, the tumour-associated tissue eosinophilia has gained growing interest in the last years. Eosinophils are a minor subpopulation of leukocytes, representing 1-3% of all circulating white blood cells. The presence of high levels of eosinophils is associated with several diseases, but their role in cancer pathophysiology is controversial. In particular, an uncertain and contradictory relationship exists between the exact role of tumour-associated tissue eosinophilia and oral cancer development. Many studies have shown that tumour-associated tissue eosinophilia increases both in the progression of oral potentially malignant disorders as well as in the grade and stage progression of oral cancer. Despite this, both negative and positive prognostic outcomes have been associated with eosinophil infiltration. The heterogeneous results may be partially due both to several methodological inconsistencies and to an incorrect interpretation of the physiological role of eosinophils. Therefore, further studies to elucidate the contribution of eosinophil infiltration are needed, focusing on the existence of eosinophil subpopulations regulated by the cancer immune microenvironment. Furthermore, the correct reporting of prognostic marker research is encouraged, in order to ensure the reproducibility and the comparability of the results from different studies.

Quantitative analysis of tumor-associated tissue eosinophils and tumor-associated blood eosinophils in oral squamous cell carcinoma

Background:

Stromal response to cancer is usually characterized by intense lymphoplasmacytic infiltrate. However, recently, the attention has shifted to tumor-associated tissue eosinophils (TATE). Tumor-associated blood eosinophils (TABE) are rare in solid cancers; however, carcinoma of the head and neck shows its prevalence.

Aim:

The aim of the study was to investigate the prevalence and relationship of tissue and blood eosinophils in various grades of oral cancer. The purpose of the article is to emphasize the possible clinical and biological significance of eosinophils in patients of oral squamous cell carcinoma (OSCC) so that appropriate therapeutic strategies can be devised accordingly.

Study Design:

Thirty histologically confirmed cases of oral squamous cell carcinoma were divided into well, moderate and poorly differentiated carcinoma. Eosinophilic infiltration in the tissue was graded as low, moderate and massive TATE. The number of eosinophils per 100 WBCs was taken as the differential eosinophil count. Blood eosinophilia (BE) >6% was considered to be TABE.

Materials and Methods:

Hematoxylin and eosin-stained tissue sections at 5 μ were evaluated. Prolonged staining in dilute 0.05% aqueous eosin demonstrated eosinophils selectively. Blood smears were stained by Leishman stain.

Statistical Analysis:

Student's t-test, Chi-square test, ANOVA, Newman–Keuls Multiple Comparison Test and Karl Pearson correlation coefficient® method were used.

Results:

The mean TATE value was highest in poorly differentiated carcinoma. TABE was seen only in a few cases and was associated mostly with poorly differentiated OSCC.

Conclusion:

There was a statistically significant correlation between TATE and histological grades of OSCC. Eosinophilia of the peripheral blood is an adverse sign in patients with carcinoma.

Eosinophil Density in Common Benign and Malignant Salivary Gland Tumors with Congo Red Staining

Purpose: Eosinophils are multifunctional leukocytes with unknown mechanisms in salivary gland tumors. Some researchers associate eosinophils with tumor progression and others have proposed them as antitumoral. The present study was conducted to compare the density of eosinophils in common salivary gland tumors and its relationship with the degree of differentiation in malignant salivary gland tumors. Materials and Methods: In this present descriptive-analytical, cross-sectional study, 15 cases of pleomorphic adenoma, 15 cases of adenoid cystic carcinoma (ACC), 30 cases of mucoepidermoid carcinoma (MEC), and 5 cases of normal salivary glands were extracted. Sections were prepared of these cases for Congo red staining. The malignant salivary gland tumors were classified as high-grade and low-grade malignancies. The slides were observed under ×10, and the highest-density areas were selected and counted in ten microscopic fields under ×40. Results: The density of the eosinophils was 4.5 ± 5.6 in the pleomorphic adenoma, 16.2 ± 6.01 in the low-grade MEC, 1.05 ± 1.1 in the high-grade MEC (Grade III), and the ACC, and 0.4 ± 0.89 in the normal salivary gland. Eosinophil density was significantly higher in low-grade malignancies compared to in benign or high-grade malignant neoplasms and normal salivary gland (P < 0.001). Conclusion: This is suggested which the density of eosinophils is associated with the process of tumorigenesis and the degree of malignancy in malignant salivary gland tumors.

Eosinophils: An imperative histopathological prognostic indicator for oral squamous cell carcinoma

Background

Inflammation in tumor microenvironment assists in both promotion and growth of tumor. Tumor-associated tissue eosinophilia (TATE) is the term used when eosinophils are observed in a tumor tissue with inflammatory infiltrate. Although carcinogenesis with inflammation is one of the important hallmarks, the exact role of eosinophils remains unclear. Various studies on oral squamous cell carcinoma (OSCC) that focused on eosinophils reported both favorable and unfavorable prognosis in cancer tissue, because of which the exact function of eosinophils still remains uncertain.

Aims and Objectives

The present study aims at identifying the role of TATE in OSCC and in malignant transformation of oral epithelial dysplasia (OED).

Materials and Methods

The study includes 70 samples that divided into two groups, of which 50 histopathologically proven cases of different grades of OSCC and 20 cases of OED (oral leukoplakia). Congo red stain was used to stain the tissue sections. Each slide was viewed under high power in 10 consecutive microscopic fields for counting of eosinophils.

Results

Statistical analysis of values obtained was done using ANOVA, unpaired t-test and Mann-Whitney test. The results were statistically significant (P < 0.05) with a mean total eosinophil count of 2.12 in OED and 4.31 in OSCC.

Conclusion

The present study showed higher eosinophil counts in OSCC when compared to dysplasia which should prompt for a thorough evaluation of tumor front for invasiveness. Therefore, tissue eosinophil count may be used as an adjunct to predict the malignant transformation of dysplastic lesions to OSCC.

Tissue eosinophilia in oral intraepithelial neoplasia as a probable indicator of invasion

OBJECTIVE

To investigate the presence of eosinophils in oral intraepithelial neoplasia (OIN) and oral squamous cell carcinoma (OSCC) lesions and its relation to invasion.

SUBJECTS AND METHODS

Ninety-nine oral biopsies were selected and subdivided into the following: OIN-1(16 cases), OIN-2 (18 cases), OIN-3 (17 cases), microinvasive OSCC (10 cases), non-metastatic OSCC (22 cases) and metastatic OSCC (16 cases). The tissue eosinophilia was evaluated histologically in slices stained with haematoxylin and eosin.

RESULTS

Eosinophil distribution was associated with diagnosis severity (p < .01). A significant difference was found between OIN-3 or microinvasive OSCC and non-metastatic or metastatic OSCC. Stromal invasion threshold was 7 eos/10 high power field (hpf) (96.1% specificity and 62.5% sensitivity). Eosinophils were absent in OIN-1; in OIN-2, two cases were positive. In OIN-3, five cases showed tissue eosinophilia, four of which had ≥3 eos/hpf or ≥7 eos/10 hpf. Three cases were suspected of invasion; two had a previous history of OSCC with elevated eosinophil infiltrate. In microinvasive OSCC, the four positive cases presented ≥3 eos/hpf and ≥7 eos/10 hpf. Although not significantly different, non-metastatic invasive OSCC had a higher number of cases (68.2%) with ≥22 eos/10 hpf contrasting with 50% in metastatic OSCC.

CONCLUSION

Our results suggest that eosinophils can be considered an indicator of invasion in OIN, helping in cases of difficult diagnosis.

Squamous Cell and Adenosquamous Carcinoma of Gall Bladder: a Clinicopathological Study of 8 Cases Isolated in 94 Cancers

Adenosquamous/squamous cell carcinoma (AS/SCC) of the gall bladder is a rare histopathologic subtype that accounts for 1 to 12% of all the gall bladder carcinomas (GBC). Literature on these malignancies is limited. A retrospective analysis of 8 cases (study group) of pathologically proven AS/SCC of the gallbladder among 94 patients who underwent surgery for GBC from January 2001 to December 2014 was done. Twenty-four conventional gall bladder adenocarcinoma cases were selected as control group after matching for age and gender. Mean patient age was 57.8 years and six were females. Clinical presentation did not seem to be too different among the study and control group. Average tumor thickness was significantly higher in AS/SCC cases as compared to the control group (mean 3.1 versus 1.44 cm; p = 0.001). Immunohistochemistry for Ki-67 in adenosquamous carcinoma of the gall bladder showed much higher proliferative index in squamoid area than the adenocarcinoma areas (mean 31.3 versus 16.8%; p = 0.0004). Study group showed 87.5% patients were in higher stage whereas only 37.5% of the patients in control group presented at a higher stage. AS/SCC of the gall bladder presented at an advanced stage. Higher proliferation index in squamous component of adenosquamous carcinomas may account for higher T stage in these malignancies.

Emerging Roles for Eosinophils in the Tumor Microenvironment

Eosinophils are evolutionary conserved cells largely studied in the context of allergy. Although eosinophils were first described in tumors more than 120 years ago, their roles in cancer are often overlooked. This is puzzling given their potent immune modulatory, cytotoxic, and/or tissue repair capabilities, and recent studies demonstrating key roles for eosinophils in contexts far beyond their 'classical' field (e.g., metabolism, thermogenesis, and tissue regeneration). Recent data suggest that this frequently ignored cell is emerging as a potent immune effector and immune modulator in the tumor microenvironment. This review discusses the relevance of eosinophils to tumorigenesis and the potential to harness their function in cancer therapies.

Tumor eosinophil infiltration and improved survival of colorectal cancer patients: Iowa Women's Health Study

The role of the innate immune response in colorectal cancer is understudied. We examined the survival of colorectal cancer patients in relation to eosinophils, innate immune cells, infiltrating the tumor. Tissue microarrays were constructed from paraffin-embedded tumor tissues collected between 1986 and 2002 from 441 post-menopausal women diagnosed with colorectal cancer in the Iowa Women's Health Study. Tissue microarrays were stained with an eosinophil peroxidase antibody. Eosinophils in epithelial and stromal tissues within the tumor (called epithelial and stromal eosinophils, hereafter) were counted and scored into three and four categories, respectively. In addition, the degree of eosinophil degranulation (across epithelial and stromal tissues combined) was quantified and similarly categorized. We used Cox regression to estimate the hazard ratios and 95% confidence interval for all-cause and colorectal cancer death during 5-year follow-up after diagnosis and during follow-up through 2011 ('total follow-up'). The hazard ratios associated with eosinophil scores were adjusted for age of diagnosis, SEER (Surveillance, Epidemiology, and End Results) stage, tumor grade, body mass, and smoking history. High tumor stromal eosinophil score was inversely correlated with age and stage, and was associated with a decreased risk for all-cause and colorectal cancer death: hazard ratios (95% confidence intervals) were 0.61 (0.36-1.02; P-trend=0.02) and 0.48 (0.24-0.93; P-trend=0.01), respectively, during the 5-year follow-up for the highest vs lowest category. The inverse associations also existed for total follow-up for all-cause and colorectal cancer death for the highest vs lowest stromal eosinophil score: hazard ratios (95% confidence intervals) were 0.72 (0.48-1.08; P-trend=0.04) and 0.61 (0.34-1.12; P-trend=0.04), respectively. Further adjustment for treatment, comorbidities, additional lifestyle factors, tumor location, or molecular markers did not markedly change the associations, while adjustment for cytotoxic T cells slightly attenuated all associations. The infiltration of tumors with eosinophils, especially in stromal tissue, may be an important prognostic factor in colorectal cancer.

Tumour-Associated Tissue Eosinophilia in Oral Squamous Cell Carcinoma- A Boon or a Bane?

INTRODUCTION

The infiltration of tumour stroma by eosinophils, Tumour-Associated Tissue Eosinophilia (TATE) is known to modulate the evolution of Oral Squamous Cell Carcinoma (OSCC). Identification of eosinophils in the inflammatory stroma has been proven to be an important factor in prognostication of malignant tumours including cancers of mouth, oesophagus, larynx, pharynx, breast, lung, intestine and genitourinary tract.

AIM

Our study aimed to assess the role of TATE as a prognosticator in OSCC as visualized by Haematoxylin and Eosin (H&E) and congo red staining.

MATERIALS AND METHODS

Thirty histologically-proven cases of OSCC were retrieved from the archives of Department of Oral Pathology, Manipal College of Dental Sciences, Mangalore, Manipal University, Karnataka, India. Two serial sections of 4μm thickness were made and subjected to routine staining with H&E and modified congo red staining, where eosinophil granules stained red and nuclei stained blue. In 40x magnification, 10 HPF at invasive tumour front were assessed for counting eosinophils by placing a 49 square grid (measuring 0.0289 sq mm).

STATISTICAL ANALYSIS

The TATE was compared with the prognosticators using Mann-Whitney U-test. The grades of carcinoma were correlated with TATE using Kruskal-Wallis test followed by Post-hoc Bonferronis correction. Agreement of the number of eosinophils counted in the two staining techniques (H&E and Congo red) in OSCC was achieved using interclass correlation coefficient, and Friedman's test. A value of p< 0.05 was considered statistically significant.

RESULTS

Our results showed that tissue eosinophil counts were higher in well-differentiated cases of OSCC, cases with lymph node involvement, decreased survival, without margin involvement and in cases that did not recur. H&E stain showed significantly better visualization of eosinophils resulting in higher eosinophil counts than when seen with Congo red (p=0.008).

CONCLUSION

Thus, TATE can be used as a surrogate marker in prediction of survival and recurrence in OSCC. H&E proved to be a better stain for evaluation of eosinophils.

Comparative evaluation of eosinophils in normal mucosa, dysplastic mucosa and oral squamous cell carcinoma with hematoxylin-eosin, Congo red, and EMR1 immunohistochemical staining techniques

Background:

Oral squamous cell carcinoma is the most common malignant lesion of the oral cavity, and it involves various molecular mechanisms. The development of oral squamous cell carcinoma is influenced by the host immune cells, such as eosinophils. The present study was conducted to compare the presence of eosinophils in normal mucosa, dysplastic mucosa, and oral squamous cell carcinoma by -hematoxylin- eosin staining, Congo red staining, and epidermal growth factor-like (EGF-like) module containing a mucin–like hormone receptor1 (EMR1) immunohistochemical marker.

Methods:

In this cross-sectional study, 60 paraffinized samples were selected, consisting of 20 normal mucosae, 20 dysplastic mucosae, and 20 squamous cell carcinoma samples. After confirmation of the diagnosis, the mean number of eosinophils was evaluated by hematoxylin-eosin, Congo red, and immunohystochemical staining techniques. The data were analyzed by SPSS-10 software using the Kruskal-Wallis and Friedman tests.

Results:

The results showed that the number of eosinophils in dysplastic mucosa was significantly higher than the number in normal mucosa, and the number of eosinophils in squamous cell carcinoma was significantly higher than the number in dysplastic mucosa in all staining techniques (p<0.001). Moreover, the comparison of staining techniques showed a significantly higher number of eosinophils in EMR1immunohistochemicalmarker than were observed when Congo red and hematoxylin - eosin (H&E) staining techniques were used (p<0.001).

Conclusion:

It can be argued that eosinophil contributes to the identification of lesions that have a higher potential of malignant transformation. Moreover, eosinophil can be suggested as an indicator in the differentiation of oral lesions in cases with borderline diagnosis and in targeted molecular therapy.

IgE-based immunotherapy of cancer: challenges and chances

Passive immunotherapy with monoclonal antibodies is an indispensable cornerstone of clinical oncology. Notably, all FDA-approved antibodies comprise the IgG class, although numerous research articles proposed monoclonal antibodies of the IgM, IgG, IgA and IgE classes directed specifically against tumor-associated antigens. In particular, for the IgE isotype class, several recent studies could demonstrate high tumoricidic efficacy. Therefore, this review specifically highlights the latest developments toward IgE-based immunotherapy of cancer. Possible mechanisms and safety aspects of IgE-mediated tumor cell death are discussed with special focus on the attracted immune cells. An outlook is given on how especially comparative oncology could contribute to further developments. Humans and dogs have a highly comparable IgE biology, suggesting that translational AllergoOncology studies in patients with canine cancer could have predictive value for the potential of IgE-based anticancer immunotherapy in human clinical oncology.

A histochemical study of tissue eosinophilia in oral squamous cell carcinoma using Congo red staining

BACKGROUND

Tumor associated tissue eosinophilia is believed to play a significant role in the biological behavior of the carcinoma. Eosinophil infiltrate in association with the head and neck squamous cell carcinoma (SCC) have been reviewed from time-to-time. The significance of such an association has been variably thought to be either a potential diagnostic tool for stromal invasion or as a prognostic indicator. We aimed to evaluate the efficacy of Congo red staining to differentiate eosinophils in the inflammatory infiltrate in oral squamous cell carcinoma (OSCC) and whether this eosinophilia is associated with the histologic grading in OSCC.

MATERIALS AND METHODS

The eosinophil infiltration in hematoxylin and eosin (H and E) and Congo red stained sections of 50 biopsies of OSCC were examined. The eosinophil distribution was quantitatively evaluated in both sections as either diffuse or focal and scored as mild, moderate and severe grades. The average number of eosinophils obtained in OSCC stained by H and E and Congo red were then statistically compared by univariate analysis carried out using Student's t-test. P < 0.01 was used to determine the statistical significance.

RESULTS

In the OSCC, the eosinophil infiltration was seen in 43 out of 50 (86%) cases. The elevation of eosinophil count was more diffuse than focal (36 vs. 7 [83.72 vs. 16.27%]). The staining efficacy of Congo red stain over H and E stain to differentiate eosinophils was excellent and found to be statistically significant (P < 0.01). No significant correlation was found with the eosinophil infiltration and the histologic grades of OSCC.

CONCLUSION

Our study showed a strong infiltration of eosinophils in OSCC though no significant correlation was found with the eosinophil infiltration and the histologic grades of OSCC. Congo red staining showed a high sensitivity in staining eosinophils over routine H and E. This staining technique could therefore provide an adjunct to routine H and E in evaluating eosinophils in dysplasia and OSCC cases.

Differences in the concentration and correlation of cervical immune markers among HPV positive and negative perimenopausal women

INTRODUCTION

Women≥45years of age with persistent HPV infections have distinct peripheral circulating immune profiles. Few studies have comprehensively evaluated the cervical immunologic microenvironment in HPV-positive and HPV-negative perimenopausal women.

METHODS

We collected cervical secretion specimens from 34 high risk HPV (HR-HPV) positive and 44 HR-HPV negative women enrolled in an ongoing prospective cohort assessing the natural history of HPV across the menopausal transition. We used these specimens to quantify concentrations of 27 different immune markers using multiplexed bead-based immunoassays.

RESULTS

HR-HPV positive women had significantly higher median concentrations of IL-5 (0.11 ng/mgtotal protein vs. 0.08 ng/mgtotal protein), IL-9 (2.7 ng/mgtotal protein vs. 2.1 ng/mgtotal protein), IL-13 (2.1 ng/mgtotal protein vs. 0.9 ng/mgtotal protein), IL-17 (2.9 ng/mgtotal protein vs. 1.1 ng/mgtotal protein), EOTAXIN (4.1 ng/mgtotal protein vs. 1.1 ng/mgtotal protein), GM-CSF (4.3 ng/mgtotal protein vs. 3.3 ng/mgtotal protein), and MIP-1α (3.5 ng/mgtotal protein vs. 1.9 ng/mgtotal protein) compared to HR-HPV negative women. A shift in the correlation of T-cell and pro-inflammatory cytokines (IFN-γ, IL-5, IL-9, IL-10, IL-12, IL-13, IL-15, and TNF-α) from IL-2 to EOTAXIN was observed between HR-HPV negative and positive women.

CONCLUSIONS

Higher local concentrations of anti-inflammatory and allergy associated markers, with a shift in T-cell associated cytokine correlation from IL-2 to EOTAXIN, are associated with HPV infection among older women.

Plasmin inhibitor reduces T-cell lymphoid tumor growth by suppressing matrix metalloproteinase-9-dependent CD11b(+)/F4/80(+) myeloid cell recruitment

Activation of the fibrinolytic system during lymphoma progression is a well-documented clinical phenomenon. But the mechanism by which the fibrinolytic system can modulate lymphoma progression has been elusive. The main fibrinolytic enzyme, plasminogen (Plg)/plasmin (Plm), can activate matrix metalloproteinases (MMPs), such as MMP-9, which has been linked to various malignancies. Here we provide the evidence that blockade of Plg reduces T-cell lymphoma growth by inhibiting MMP-9-dependent recruitment of CD11b(+)F4/80(+) myeloid cells locally within the lymphoma tissue. Genetic Plg deficiency and drug-mediated Plm blockade delayed T-cell lymphoma growth and diminished MMP-9-dependent CD11b(+)F4/80(+) myeloid cell infiltration into lymphoma tissues. A neutralizing antibody against CD11b inhibited T-cell lymphoma growth in vivo, which indicates that CD11b(+) myeloid cells have a role in T-cell lymphoma growth. Plg deficiency in T-cell lymphoma-bearing mice resulted in reduced plasma levels of the growth factors vascular endothelial growth-A and Kit ligand, both of which are known to enhance myeloid cell proliferation. Collectively, the data presented in this study demonstrate a previously undescribed role of Plm in lymphoproliferative disorders and provide strong evidence that specific blockade of Plg represents a promising approach for the regulation of T-cell lymphoma growth.

The role of eosinophils and eosinophil cationic protein in oral cancer: a review

Eosinophils are multifunctional leukocytes implicated in the pathogenesis of numerous inflammatory processes, such as allergies and parasitic infections. Increased number of these cells has been described in many human cancers, including oral squamous cell carcinoma, and its presence related to favourable as well as unfavourable prognosis. Although the exact role of eosinophils in tumours is not yet defined, the anti-tumour activity of these rare granulocytes has been associated with the release of their cytotoxic proteins, especially the eosinophil cationic protein, a single polypeptide chain with a molecular mass ranging from 15 to 22kDa encoded by the RNSE3 gene located on chromosome 14q11.2. Functional studies have implicated ECP in numerous processes, such as tissue remodelling in allergic inflammation; however its most striking function is the cytotoxic activity. The aim of this review is to summarise the role and functions of eosinophils and their granule-derived products in oral malignant tumours and the clinical value of the tumour-associated tissue eosinophilia for patients' prognosis.