Postradiation immunosuppressive and attractive volatile secretions: The “baystander effect” or allelopathy in groups of animals

Abstract

It was shown earlier that mice or rats exposed to sublethal doses of ionizing radiation are able to decrease the immune reactivity of intact animals when kept together with them in the same cage for 10-15 days [1]. The same effect was observed in the presence of urine of irradiated animals, when a sheet of paper that for one day adsorbed urine of irradiated animals was placed in a cage with intact animals [2,3]. In both cases, the content of antibody-forming cells (AFCs) induced with sheep erythrocytes ( 1 × 10 8 cells injected intraperitoneally) in the spleen of intact mice by the method of Cunningham, as well as the number of leukocytes in the thymus and blood of rats significantly decreased. This effect developed without immediate access of intact animals to the paper (in all cases, the latter was located under the lattice bottom of the cage) and was due to the appearance of immunosuppressive volatile compounds in the urine of irradiated animals.A similar immune suppression was achieved when intact hybrid males F 1 CBA × C57BL/6 weighing 22-24 g were exposed either for 24 h to urine samples of irradiated animals (the content of ABFs in the spleen decreased to 62 ± 5 .6% from the control) or for 60 min to volatile secretions of mice irradiated with a dose of 4 Gy on a Gamma-cell 220 device with 60 Co ( 60 ± 12% ). Hereafter, only significant differences M ± m ( n = 5 or 6) determined using Student's t -test are shown. The decrease in the immune response in mice exposed for 10 or 30 min was nonsignificant.To assess the degree of volatility of secretions analyzed, urine collected from five CBA males weighing 23-24 g during the third day after irradiation with a dose of 4 Gy was divided into three portions (0.5 ml each). The first portion was heated to 40°ë for 20 min and loaded onto filter paper; the second portion was loaded onto paper without any pretreatment; and the third portion was placed into a polyethylene bag. In the control, the same volume of urine of intact animals was loaded on filter paper. All samples were placed for one day under the lattice bottom of the cage where intact recipient mice were kept. After one day of exposure, the ability of intact mice to develop immune response was determined by the same method as in previous experiments. We discovered that, in the group of mice exposed to urine samples of irradiated animals, the content of AFCs decreased to 56 ± 4 .7%. In groups of mice exposed to thermally treated urine of urine samples placed in polyethylene bags, the immunosuppressive effect was not observed.The stable effect observed as a result of one-day exposure allowed us to study the time course of secretion of immunosuppressive volatile substances by irradiated animals. Exposure of irradiated recipient mice to urine samples collected using paper sheets during the first say after irradiation with doses 2 or 4 Gy did not significantly affect the content of AFCs in the spleen. Urine samples collected on the third day after irradiation with a dose of 2 Gy had no a significant effect; howeve...

Bystander Effect between Zebrafish Embryos in Vivo Induced by High-Dose X-rays

“…There has been only a scarce amount of studies on radiation induced bystander effect (RIBE) on the interorganism level including the study on RIBE between mice by Surinov et al, 2 and study on RIBE between whole fish by Mothersill's group 4,5 as described in the Introduction. The first part of the present study demonstrated the successful induction of the bystander effect in 10 naive embryos by partnering them with the 50 irradiated embryos (irradiated with 4 Gy of X-rays at 5 hpf) in the same medium immediately after irradiation until 25 hpf.…”

“…Surinov et al 2 reported RIBE between mice and revealed that the bystander signal was transmitted through urine. RIBE has also been shown to occur between fish.…”

Embryos of the zebrafish Danio rerio in studies of non-targeted effects of ionizing radiation

“…It would also be interesting and beneficial to study whether the CF can be transmitted at the inter-organismic level. Recently, there has been massive evidence of the RIBE occurring at the inter-organismic level, e.g., between mice [50,51], zebrafish [52] and medaka [53].…”

Bystander effects in tumor-free and tumor-bearing rat brains following irradiation by synchrotron X-rays

“…Th ese eff ects have also been related to RIBE (Surinov et al 2005). Th erefore, the authors suggest that the cause of the marked error bars may be related to the amount of urine that the bladders were holding at the moment of culturing tissue explants or it may also be individual variation in the reporter cell response.…”