Study On The Relationship Of Cell Adhesion Molecules And Radiation Dose

Both nuclear war and catastrophic nuclear accidence could cause a large scale of victims in very short time. A simple, reliable and rapid method of dose determination for exposure population was needed during the triage, diagnosis, and treatment for victims.Current methods of determining human irradiation dosages are classified into physical and biological two categories. Physical dosimetry, which is direct and precise, often relies on sufficient preparations before use. But the fact is that nuclear war and accident occur often suddenly and unpredictably and irradiated individuals are rescued from the contaminated site immediately. In this situation, direct physical determination is not only inconvenient but also heavy limitation in practice. In these circumstances, an optimal alternative method is the biodosimetry. Further more, an ideal biodosimetry must involve several factors, such as a good sensibility and specific response to irradiation, low background value, wide dose ranges and simple quick method etc.Biodosimetry is method to evaluate dosage on a relationship between radiation quantities and effects by analysising the changes of quantity, concentration, activity and function in bio-material after irradiation. Compared with physical dosimetry, biodosimetry is individual-oriented and less influenced by lots of unpredicted factors, such as body movements and ways of radiations etc. It has more advantages in rapid dosage scanning, quick triage, and diagnosis in rescue of large amount of individuals in accident.There are many methods and guidelines in regard to bio-dosage evaluation through world, such as lymphocyte counts, Chromosome aberration assay, Premature chromosome condensation assay (PCC), Micronucleus assay, Glycophorin A (GPA), Hypoxanthine-guanine phosphoribosyltransferase(HPRT), mitochondrial DNA mutations (mtDNA4977 deletion assay), Gene microarray assay. Many others havebeing studied right now. Common defect exiting in these biodosimetries is the limited doses range that can be indicated and poor reproductable because of using different experimental techniques. So till now many of these methods are not widely accepted besides lymphocyte counts and chromosome aberration analysis in low dose range evaluation. Meanwhile, some analysis are time and labor consuming and thus not suitable for quick diagnosis demanding in early stages. In view of worldwide concern on emergency medicine rescuing during meeting a radiation attack, an optimal bio-dosage indicator pursuing has been starting in the worldwide. In this field, Chinese researchers worked only following on the researches from the developed countries. Although there have been reports on chromosome aberration, GPA, HPRT analysis and some of these methods have been applied to dose retrospecting investigation in domestic radiation accidents, all of these analyses have met the same problem as foreign researchers done. According to this, it is very necessary to build an integrated biodosimetry examination technique and evaluation system which can simply rapidly and exactly response the radiation dose.Cell adhesion molecules (CAMs) are a group of membrane or transmembrane glycoproteins which modulate the cell-cell and cell-extracellular matrix interaction. CAMs are of fundamental importance in the regulation of immunity, inflammation, tissue remodeling, and embryonic development .They comprise different families of homologous proteins, such as selectins, integrins, cadherins, and immunoglobulin superfamily. In addition, beyond these groups, other structures with adhesive properties, such as proteoglycans, occludin, and CD44, has been characterized recently.Recently, many publications showed that ionizing irradiation can induce the changes of CAMs in normal tissue or tumor tissue on those who received radiotherapy. A good dose-effect pattern was found between expression of CAMs and exposure dose. Because of CAMs can also intermediate the cellular adhesive and migrating, our interesting is whether CAMs expression and their biological functions involved in adhesion and migration can be used as a new biodosimetry through checking the changes on both of the CAMs expressing and mediated cellular adhesion and-7-migration abilities at different post irradiation time. To explore the dose-effect relationship we study the changes of CAMs expression on granulocyte, lymphocyte and monocyte when human peripheral blood was exposured to different doses of gamma ray in vitro analysis, the various adhesive abilities of peripheral blood mononuclear cells (PBMC, including lymphocyte and monocyte) to different substances and then we testify rat PBMC adhesive abilities to various substances, chemotaxis index to MlP-la and the expression of Fcyll receptor(FcyRII) on lymphocyte after rats was exposured to y ray whole body. The potential use of the CAMs expression and their biological function index in biological dosimetry applications will be discussed in this dissertation.Objects: To elucidate the relationship between CAMs expression on human granulocyte, PBMC and radiation doses, the correlation between PBMC adhesive abilities to specific or non-specific substances and radiation doses. Then testify them on rats when rats whole body exposure to different doses y ray.Methods: Human heparinized veinal blood from five volunteers were irradiated using a 60Co y ray resource with single doses of 0, 2.0, 4.0 and 6.0 Gy at a mean dose rate of 0.4Gy/min, respectively. After irradiation cells were kept in culture medium (adding equal volume RPMI-1640, 37°C, 5% CO2 and 95% humidity) for 6 to 24 h before flow cytometry analysis and adhesion assay. A flow cytometry was used to determinate the expression of adhesive molecules such as CDlla^ CDllb> CD 18^ CD29> CD49d and CD54 which are adhesive function in different cells(granulocyte, lymphocyte and monocyte). PBMC were isolated from heprzinized blood using density-gradient centrifugation (Ficoll method). Cell adhesion analysis was performed to determine the PBMC adhesion abilities to different substance coated on 96-well enzyme-labeled plates at 6h> 12h and 24h post irradiation. Based on these, we testify the results on rats when rats whole body exposred to y ray. Moreover, FcrRII expression on rats lymphocyte were obtained with flow cytometryResults: (1) At each time checked point, CAMs expression didn't change obviously on lymphocyte, but both on granulocyte and monocyte, a relative good dose-effect pattern was found between expression of CD29 and exposure dose.Compared with non-irradiation groups, At 6h after irradiation, CD29 expression of 2Gy groups and 4Gy groups was increased 22.0% and 7.1% on granulocyte, 15.7% and 11.3% on monocyte, respectively, with P>0.05 in each groups. While at 24h after irradiation CD29 expression of 4Gy and 6 Gy groups was decreased 13.9%(P>0.05) and 33.1%(P<0.05) respectively on granulocyte. A reverse-ratio seemed to be found between the expression of CD18, CDllb, CD54 and irradiation doses on monocyte. And it seemed that the expression of CDlla and CD49d did not change distinguishably after irradiation both on granulocyte and monocyte. (2) In vitro, Cell adhesive assay showed that more adhesive cell numbers can be observed in radiation groups compared to non-radiation groups in IgG-coated plates under microscopy. PBMC adhesive abilities to IgG-coated plates increased 35.6% and 38.4% in 4Gy and 6Gy groups at 6h after irradiation, respectively, with a P of <0.05. In specific pi -integrin coated plates, PBMC adhesive ability increased in 2Gy and 4Gy groups, decrease in 6Gy groups at 6h after radiation, this is related to the change of CD29 expression;In non-coated plates, the adhesive abilities didn't changed. (3) When rats whole body exposured to y ray, the adhesive cells can hardly be observed in anti-rat IgG coated plate under microscopy and the PBMC chemotaxis index decreased in all irradiation groups. Further investigation indicated that the expression of FcYRII, which mediated PBMC adhesion to IgG, declined by 26.4%, 51.9% and 40.3% in 2Gy, 4Gy and 6Gy groups, respectively, at 6h after irradiation all with a P of <0.01. (4) Compared to non-irradiation gropus, PBMC migration ability decreases21.1%, 24.4%, 47.8% in 2Gy, 4Gy and 6Gy groups, respectively, at 6h after irradiation when rats whole body exposured to y ray, with a P of >0.05.Conclusion: In vitro, ionizing irradiation can cause the changes of CAMs expression on human granulocyte and monocyte, followed with changes of PBMC adhesive abilities. But only a weak dose-effect pattern was found between expression of CD29 and exposure dose. In rats, PBMC adhesive abilities to IgG decreased at three radiation groups when whole body exposured to y ray, this maybe be contributed to the down-regulation of FcYRII expression which mediates PBMC adhesion to IgG. The down-regulation of FcrRII expression was significant and dose-dependent. Thedata at present suggests that CAMs expression and biological function mediated by CAMs used as a new potential biodosimetry needs to be researched intensely.