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INTRODUCTION. The toxicity of reactive oxygen or lipid peroxide in the body has been related to the etiology of diseases such as atherogenesis, carcinogenesis and degenerative diseases. Thus, measuring the lipid peroxide levels in plasma and urine of patients suffering from these diseases is worthwhile.

Malondialdehyde (MDA) is a volatile β-escission product formed from the peroxidation of certain polyunsaturated fatty acids and is considered an index of lipid peroxidation and hence of the oxidative stress. MDA has been implicated in aging, mutagenesis and carinogenesis, and is a highly reactive compound and is well documented that it undergoes reactions with aminoacids, proteins and nucleic acids.

Immune function is considered one of the most important defense systems of our body. Although it plays no direct role in initiation and promotion of carcinogenesis, a poor immune system could allow certain types of newly formed cancer cells to establish in the host. Such an impaired immune system may also contribute to accelerated growth of established cancer cells. Therefore, the improvements in immune functions could be useful not only in maintaining good health, but also in reducing the risk of diseases including cancer.

OBJECTIVE. The objective of the present study is to determine 1) the MDA concentration as an index of oxidative stress, in blood and urine, 2) the TTL (test of lymphocyte proliferation) in plasma as a measure of immune function, during a six month period of vitamin intake by healthy volunteers, in order to study the evolution of the oxidative stress together with the degree of stimulation of the immune function during the period of vitamin intake.

MATERIAL AND METHODS

Samples Healthy volunteers (24) from 20 till 72 years, have been taking multivitamin supplements (SEVAK) during a six month period. Blood and urine samples were taken each two weeks during such period. The control group was formed by the same volunteers who, during a two month period prior to the study, did not take vitamins. The same analyses were carried out.

Oxidative stress. MDA in serum and urine was measured in triplicated by HPLC determination, using a Waters HPLC equipment, WATERS BREEZE HPLC system, waters 2487, dual lambda absorbance detector, Waters 1525 binary HPLC pump, with a nucleosyl column, 5μ C18, 100A, 250 x 4.6 mm.

Equal amounts of blood and ethanol were stirred and then other two volumes of alcohol added, centrifuged and the resulting supernatant directly applied to the HPLC column, reading at 267-350 nm for MDA. Similar sample treatment was done for reading blood at 292-325 nm but adding also two volumes of standard E to the final mixture. Equal amounts of urine and ethanol for HPLC were stirred, then centrifuged and the resulting supernatant injected directly to the HPLC column, reading at 267nm for MDA, and at 285-292 nm, to detects tocopherol derivates. The 1,1,3,3, tetraethoxypropane (TEP) was used as MDA standard.

Immune system. The test of lymphoblastic transformation (TTL) is based on the capacity of T-lymphocytes to transform themselves into blastic cells when they are grown in the presence of the antigen Phytohemagglutinine (PHA). A microscopic observation was carried out, in order to measure the evolution of blastic transformation in the population under study, considering normal values of reference a blastic transformation from 60-80%.

Statistics. Differences between treatment and the control group were assayed using the non-parametric proof of Mann Whitney to detect significative differences.

RESULTS As an average, a decreasing of nearly 4 times in blood MDA concentration is observed during the six month period that volunteers were taking supplements, varying with the age of people involved. MDA elimination by urine decreased considerably. T-lymphocytes in vitro began a quick proliferation phase into blastic cells that was increasing together with the period involved in the present study.

DISCUSSION Meanwhile volunteers were taking vitamins during a six month period, the MDA evolution was decreasing in its concentration in blood and urine. Thus, vitamins were influencing in diminishing oxidative stress represented by MDA, generated by lipid peroxidation of cell membranes. In parallel, the immune function was increasing in the period under study, as it was shown by the increased hence the improved function of T-lymphocytes against PHA antigen.

GENERAL CONCLUSION Oxidative stress decreases (MDA determination) meanwhile immune function increases (TTL determination) during the period of treatment with multivitamin supplements in healthy volunteers.

ACKNOWLEDMENTS This study was supported by a CTRF grant to Z. Coppes. The author wants to thank the 24 volunteers that allowed the research group to begin in Uruguay a pilot study, which will be applied to patients in the future. But the most important fact is the author is very deeply thankful that Professor Dr. Prasad accepted to speak in the author’s place at the International Conference on Nutrition and Cancer, owing to the impossibility of the author traveling to Honolulu, Hawaii.