1 ?22 ?33 ?44 ). Open in a separate window Fig. and cancer group on comparison with control. Keywords: serum immunoglobulin, circulating immune complex, oral precancer, oral cancer patients, oral squamous cell carcinoma Introduction Oral cancer is an insidious devastating malignancy and is one of the five leading cancers in India. Among the oral tumors, 90% of them are squamous cell carcinomas (SCC), arise from the mucosal lining. 1 Oral malignancy is generally preceded by potentially malignant lesions and conditions for a varying length of time. Early detection of these diseases with the discovery of immunological markers at a clinical, histological, and molecular level has significant reduction in mortality and implementation of multidisciplinary treatment programs, leading to improvement of survivorship and better quality of life. 2 Materials and Methods This study includes three main groups with 15 oral premalignant patients, 15 oral cancer patients, and 15 healthy individuals with an age of 20 years and above. Clinically and histopathologically diagnosed oral premalignant and oral cancer patients were included after obtaining an informed consent from the patients. In total, 5?mL of blood was collected by venipuncture using 24-gauge needles, and serum was separated by centrifugation at 2,500?rpm for 15?minutes. The separated supernatant was used for further estimation of serum immunoglobulins and circulating immune complexes. Serum immunoglobulins were quantified by using a diagnostic kit (Quantia-Ig turbidometric immunoassay for the estimation of immunoglobulin). In theory, the method consists of turbidometric immunoassay for the detection of immunoglobulins in human sera is based on the theory of agglutination reaction. The test specimen is usually mixed with activation buffer (R1). Alpl Anti-human reagent (R2) is usually then added and allowed to react. Presence of immunoglobulins in the test specimen results in formation of an insoluble complex producing a turbidity, which is usually measured at wavelength 340?nm. The extent of turbidity corresponds to the concentration of immunoglobulins in the test specimen. Circulating immune complexes levels were assessed by ELISA method. In total, 100 L of each calibrator, control, and 1:101 diluted sample to the appropriate wells. Incubate for 30?minutes and wash. Add 100 L of conjugate to each well. Incubate for 30?minutes and wash and then put 100 L of substrate to each well. Incubate for 30?minutes and wash. Finally, add 100 L of stop treatment for each well to stop the reaction and measure the absorbance at 450?nm. Statistical Analysis The statistical analysis was performed by using SPSS 19.0 version software. Comparison of groups were done by KruskalCWallis ANOVA test and MannCWhitney U test. A p -value <0.005 was considered statistically significant. Results In the present study, the mean serum IgA levels in oral precancer were 161.00 (???118.02) mg/dL, oral cancers were 270.67 (???171.44) mg/dL, and controls were 133.73 (???101.31) mg/dL. On comparison of three groups, it was found that serum levels of IgA in oral cancer in comparison with controls were statistically significant when compared with precancers. Mean serum levels of IgG in oral precancer were 1,430.87 (???316) mg/dL, oral cancers were 1,234.27 (???365.42) mg/dL, and controls were 593.87 (???323.06) mg/dL. On comparison of three groups, it was found that comparison between precancer and controls ( p? KY02111 Comparison of three groups (precancer, cancer, and control) with respect to IgA scores by KruskalCWallis ANOVA test