Serum total sialic acid and Hanganutziu-Deicher antibody in normals and in cancer patients.

OBJECTIVE: To determine the levels of both TSA and HD antibody in sera of patients with various malignancies and evaluate their potential role as diagnostic and/ or prognostic markers. DESIGN: Laboratory based analysis. SETTINGS: Kenyatta National Hospital, Kenya Medical Research Institute and the Department of Biochemistry, University of Nairobi. SUBJECTS: A total of 909 serum samples, 420 from cancer patients recruited at Kenyatta National Hospital and 509 from normal blood donors recruited at Nairobi Hospital. RESULTS: The mean age for the patients and controls was 36 and 37 years respectively. Carcinoma patients constituted 54%, sarcoma 12.1%, lymphoma 16.4% and 17.4% had other types of tumours. The mean TSA in patients was 0.86 mg/ml +/- 0.026 compared to 0.82 mg/ml +/- 0.014 in controls. The TSA level was significantly higher in patients compared to controls (Student's t-test p = 0.031 at 0.05 confidence level). The TSA increased with age in both study groups. In patient sera, both gender gave the same mean of 0.83 mg/ml while it was 0.82 mg/ml and 0.83 mg/ml in control females and in males respectively. Sarcomas had the highest amount of 0.93 mg/ml but there was no significant statistical variation between tumour types (p = 0.076). The HD antibody mean readings were 0.004 in pathologic sera compared to 0.011 in controls. The values were significantly elevated in patients (p = 0.03) with females giving a higher value for both study groups (p = 0.628). HD antibody readings was significantly higher in carcinomas (p = 0.017) compared to those of sarcomas and lymphomas. There was no association between antibody readings and age of patient (p = 0.601). CONCLUSION: Both TSA and HD antibody values were significantly elevated in patients compared to clinically healthy controls and while TSA levels increased with age and was independent of gender, HD antibody levels were independent of age, gender and also tumour type. The study demonstrates that although TSA is normally elevated in malignancy, most of the sialic acid shed is of N-acetyl type as some patients do not express HD antibody directed to the N-glycolyl sialic acid. The reason why some tumours would express Neu5Gc at any one time needs further evaluation.

Serum Hanganutziu and Deicher (HD) antibody and total sialic acid levels in hepatoma patients.

A preliminary short follow-up study of Hanganutziu and Deicher (HD) antibody titre and sialic acid levels in sera from 7 patients with hepatoma was carried out. Weekly HD antibody titres were abnormal in 6 patients with titres of 4 of the 6 falling to normal in some weeks. Sialic acids levels, however were abnormal (3.830-6.82mmol/ l) compared to those of 33 normal sera (1.08-2.73 mmol/1) throughout the 8 week screening period. There was a poor correlation between the antibody tires and the sialic acid levels (r<0.50) suggesting that at some stage of malignancy, the tumour was expressing N-glycolylneuraminic acid (Neu5Gc), the epitope of HD antigens as well as shedding into circulation, excess N-acetylneuraminic acid (Neu5Gc). Neu5Gc is a tumor-associated antigen. Measurement of antibodies to this epitope have shown that the antibodies have a potential of offering an alternative method of determining tumor growth and/or metastases. A major follow-up study incorporating information on cancer type, disease stage, therapy and the immnunological status of the patient is called for.

Microstructure of the sialic acid moiety of N-glycolylneuraminyllactosylceramide and the elucidation of Hanganutziu and Deicher (HD) antigenicity.

The carboxyl (-COOH) group of heterophile Hanganutziu and Deicher (HD) antigen-active ganglioside (N-glycolylneuraminyllactosylceramide) was esterified (-CO2CH3) by methyl iodide and then reduced to a primary alcohol (-CH2OH) by sodium borohydride. The intact molecule (commonly known as HD3) as well as its two derivatives were tested for HD antigen potency using four human pathologic sera containing HD antibodies. The methyl ester derivative (1-methyl-HD3) gave the same inhibition potency as HD3, but the reduced HD3 gave poor inhibition (1/66) compared to the intact HD3. The results show that reduction of the carboxyl group diminishes the inhibitory potency of HD3. This suggests that although the N-glycolyl (-CH2OH) group of HD3 is the most important determinant for manifestation of HD antigenicity, it is likely that the antibody recognizes both the N-glycolyl and carboxyl groups together when they form a hydrogen bond (-CH2OH---OOC-), aided by their possible proximity, and that substitution of either group therefore reduces the reaction of HD3 with HD antibody dramatically.

A specific enzyme-linked immunosorbent assay (ELISA) procedure for detection of heterophile Hanganutziu and Deicher (HD) antibodies.

A specific, relatively sensitive, quantitative and standardized enzyme-linked immunosorbent assay (ELISA) procedure was developed for the detection of heterophile Hanganutziu and Deicher (HD) antibodies which are occasionally elevated in pathologic human sera. The HD antigen-active molecule used for the assay was a ganglioside (N-glycolylneuraminyllactosylceramide, abbreviated as NeuGc-LacCer) previously purified from horse erythrocyte membranes. The test used antigen-coated plastic microtiter plates and anti-human immunoglobulin G (IgG, Fab fragment) conjugated with alkaline phosphatase. Fifty-four normal human sera gave ELISA values ranging from -2 to 2%. Random sera from hospitalized patients were first screened by the horse erythrocyte hemagglutination (HA) test, whereby 5.7% (76 cases) gave abnormal HA titers of 128-4096 compared to titers in normal sera equal to or less than 64. Ninety-seven % of the patients' sera gave abnormal ELISA values (3-200%). They were classified into 3 groups: cancer (42 cases), infection (10 cases), and others (24 cases). The potential value of this ELISA method is discussed.

A potential radioimmunoassay system for detection of Hanganutziu-Deicher type heterophile antigen(s) and antibodies in tissues and fluids.

A relatively simple, specific and sensitive radioimmunoassay system has been developed for the detection of heterophile Hanganutziu-Deicher (H-D) antigen(s) and antibodies. The 125I-labeled H-D antigen-active molecule used for the assay is a bovine erythrocyte major glycoprotein previously found to have a strong H-D antigen potency. The antigen-antibody complex was precipitated with normal human serum as the carrier protein, followed by the addition of rabbit anti-human IgG F(ab')2 serum. With this method, different H-D antigen-active molecules were compared for heterophile H-D antigen potency with reasonable sensitivity detecting about 0.3 ng of cold glycoprotein. 8 different lung cancer tissues were assayed for H-D antigen. The sera from the 8 lung cancer patients were also screened by ELISA and RIA in an attempt to correlate expression of H-D antigen on tissues with elevation of H-D antibodies. The results showed that all patients' tissues expressed the antigen(s) but only 3 of them had abnormal levels of H-D antibodies. This could have been due to excess antigens in circulation or immune complexes.