Determination Of Serum IGAAnd IGE Levels In Patients With Squamous Cell Carcinoma Of The Oral Cavity

INTRODUCTION

The immune system plays major role in protecting the higher organisms against various diseases, especially the ones caused by external agents. Though the role of cellular and humoral immunity is well documented in case of foreign body invasion as well as in autoimmunity, limited is our knowledge regarding their role in occurrence and progression of neoplasm particularly in malignant variety.

With the advances in tumor immunology, several observations have led to the hypothesis that, development of malignancy may be due to the breakdown in immunological surveillance of the host⁹. It is documented that a state of immuno suppression can lead to the development of malignancy.⁹ A strong correlation between immunoglobulin levels and the progression of cancer has also been reported.^4,9,17,18,21 The present study was undertaken to evaluate humoral immune response in patients with oral squamous cell carcinoma; prior to therapy, after therapy and with relapse as compared to non neoplastic individuals.

MATERIALS AND METHODS

The study involved patients visiting Depart ment of Oral Medicine of Bengaluru Institute of Dental Sciences, Bengaluru as well as Kidwai Institute of Oncology, Bengaluru.

The study population were categorized into:

1) Control group – consisting 25 healthy individuals with no history of malignant neoplasm, who volunteered for the study.

2) Study group - consisting totally 100 individuals with oral squamous cell carcinoma, who were further grouped into;

Group I – Consisting 50 individuals with oral squamous cell carcinoma who were yet to undergo treatment for the neoplasm.

Group II – Consisting 25 individuals who had undergone surgery and/ or radiotherapy, chemotherapy for oral squamous cell carcinoma .

Group III – Consisting 25 individuals with relapse of squamous cell carcinoma of the oral cavity.

The study did not involve any individual with known history or features of immunological disease or disorders. Serum sample of the study population was tested for IgA and IgE. The quantitative estimation of serum IgA was done by immunoturbidimetric method, quantitative estimation of serum IgE was done by immunoenzymatic assay, which is based on immunoradiometric assay.

Reagent kit for IgA estimation contained two reagents namely:- Reagent 1 – TRIS buffer and Reagent 2 – Antiserum Anti- IgA.

The principle of immunoturbidimetric method is based on the reaction between immunoglobulin as antigen and specific antiserum as antibody where the reaction forms an insoluble complex producing turbidity, which is measured by a Spectrophotometer at 340 nm.

Reagent kit for IgE estimation contained two reagents namely:-Reagent 1- Goat anti mouse: mouse anti IgE complexes and Reagent 2 – Equine anti IgE conjugated to alkaline phosphatase.

The principle of this procedure includes a two site immunometric format where the IgE in a serum sample reacts with the paramagnetic particles which contribute to increased reaction kinetics and efficient separation of bound immunoreactants. The paramagnetic particles were coated with goat anti mouse: mouse anti IgE complexes forming the antigen antibody complex. Adding equine anti IgE conjugated to alkaline phosphatase forms the complete sandwich complex by binding to the previously bound IgE on the paramagnetic particles. Addition of chemiluminescent substrate later to the reaction vessel results in light generation. This was measured by a luminometer where the light production is proportional to the amount of IgE in the sample.

The results thus obtained were analysed statistically by student `t` test and ANOVAtest.

RESULTS

The serum IgAlevels in various groups:

On comparison with the control group, it was found that the serum IgA levels were significantly elevated in Group III, and minimally elevated in Group I and reduced in Group II. Upon comparing the results of Group I with Group II and Group III, it was found that serum IgA levels were significantly reduced in Group II and significantly elevated in Group III (Table 2) (Graph 1). Significant difference inserum IgA levels were observed between Control group & Group III, Group I & Group II, Group II & Group III by student 't' test (p <0.05), (Table 3).

By ANOVAtest significant difference inserum IgA levels were found between groups (p < 0.05). (Table 4)

The serum IgE levels in various groups:

On comparison with control group, it was found that the serum IgE levels were significantly increased in Group I & Group III and was markedly reduced in Group II.

Upon comparison of Group I with Group II and Group III, it was found that the serum IgE levels were significantly reduced in Group II and were not markedly elevated in Group III (Table 2) (Graph 1). By student 't' test, difference in serum IgE levels were highly significant between Control group & Group I (p < 0.001) and were significant between Control group & Group III, Group I & Group II (p < 0.05). (Table 3) By ANOVA test the difference in serum IgE levels were found to be significant between groups (p< 0.05) (Table 4).

DISCUSSION

Serum immunoglobulins have been assayed in various diseases. Elevated levels of proteins, mainly acute phase proteins and immunoglobulins have been found in patients with carcinomas of different histology and localization.³⁰ The humoral response in head and neck cancers does occur and is shown by the localized accumulation of plasma cells beneath/adjacent to the tumor.^17,19 The humoral responses may therefore enhance tumor formation by the production of blocking factors for cell mediated immune response in the serum, which can either be antibodies or immune complexes.⁷ Previous researchers have reported a probable involvement of IgA to coincide with increasing tumor load and IgE in the antibody dependent  cellular cytotoxicity.^3,4 

In the present study, the serum IgA and IgE levels were estimated to find out possible correlation with oral squamous cell carcinoma. Several studies have reported elevated levels of serum IgA in oral carcinoma.^5,6,7 Elevated serum IgA levels have also been reported in cancers of epithelial secretory organs such as prostate, uterus, lung,¹⁸ cervix,¹⁶ gut, skin, breast,¹ as well as head  and neck.^{3,6,7,10,17,19,22}

Increased levels of serum IgA might represent either a non-specific response to chronic mucosal irritation by alcohol, smoking, infection, trauma, viruses or a response to specific antigen.³¹ The cause of fall in serum IgA levels following radiotherapy was found to vary with the stage of the disease, efficiency of the individual's immune system and above all the extent and the duration of radiotherapy.¹⁹ It has also been reported that IgA can have a direct inhibitory effect on the normal host defense mechanisms against malignant cells.³

In the present study, the elevated serum IgA levels is found to be more significant in relapse cases (Group III) than prior to therapy (Group I), further confirming the role of immune system in occurrence of the neoplasm. At the same time it may be worth mentioning that the present study did not include through assessment of these individuals (group-III) for post oncotherapy complications such as opportunistic infections.

The serum IgE levels is found to be significantly elevated prior to therapy (Group I) and relapsed cases (Group III) and significantly reduced after therapy (Group II) when compared to control group in the present study. Previous studies have reported variable results of serum IgE in cancer patients which could be reduced, unaltered or increased.^6,12,21,23 Initial hypothesis proposed was that IgE may cause lysis of tumor cells, which is based on the 'Gate Keeper' and 'Histamine' theories. The gate keeper theory explains that the IgE released from the mast cells or basophils act as catalyst / gate keeper by altering vessel permeability and thus allowing other mediators, immunoglobulins or chemotactic substances to interact with the neoplasm.¹³ The second mechanism include the evidence of histamine by stimulating cyclic AMPwhich in turn can modulate immune responses like basophilic degranulation, cell mediated immunity, antibody production and neutrophil processes.¹³ With advances in technology it is suggested that IgE may have a beneficial role in host tumor relationship.⁷

It has been reported by previous researchers, that elevated serum IgAlevels appears to indicate adverse prognosis whereas elevated serum IgE levels appears to indicate favorable prognosis.^2,3,4,15,19

CONCLUSION

Cancers are one of the most common diseases affecting the immune status of the host. The various malignancies may be caused by immunosuppression itself or a combination of other etiological factors. Evaluation of the host defense mechanism in cancers may be of great significance in understanding the effect of cancer on the host.¹⁹ Humoral immunity is a reflection of altered cell mediated immunity in carcinoma⁸ and the immunoglobulin assays are indicators of the humoral immune response of the patients against disease.

In the present study, when compared with healthy individuals, the elevated serum IgA levels were significant in relapse cases but were not markedly elevated prior to therapy. The elevated serum IgE levels were highly significant prior to therapy and significant in relapse cases. Thus serum immunoglobulin levels may help to assess progression of the disease and correlate its relation to various treatment modalities. The serum IgAand IgE levels are a reflection of cellular immune response as their production is dependent on T– cell activity⁷. The elevated IgA levels is said to have a poor prognosis whereas the elevated IgE levels is said to have a favorable prognosis.²