title: The combined effects of reduced weightbearing and ionizing radiation on splenic lymphocyte population and function.
abstract: OBJECTIVE
  The effects of radiation +/- hypogravity on immunologic function were investigated using the Partial Weight Suspension (PWS) model ( Wagner et al. 2010 ).
  
  
  METHODS
  Mice were exposed to 0.5, 1, or 2 Gray (Gy) dose of gamma radiation and then placed in the PWS system for 4, 24, 48 hours, or 4 days. Spleens were excised and white blood cells were prepared for flow cytometry analyses.
  
  
  RESULTS
  The combination of PWS + radiation (1 and 2 Gy doses only) resulted in decreased cell viability at the 24 h (∼16% decrease), 48 h (∼20% decrease), and 4 day (∼20% decrease) time points, compared to the PWS (no radiation) and no treatment (non-suspended, non-irradiated) groups. The T lymphocyte (thymus-derived) population increased by ∼10% (24 h, 48 h, and 4 day time points), while the B lymphocyte (bursal or bone marrow-derived) population decreased by ∼10% (at all time points examined), when mice were exposed to PWS + radiation (2 Gy dose only), compared to the PWS or no treatment groups. T cell activation was observed in the PWS group and the 0.5 Gy +/- PWS groups at the 4 and 24 h time points, compared to the no treatment group. However, T cell activation was significantly suppressed (∼85%) at the acute time points in the 2 Gy +/- PWS groups, comparable to the no treatment group.
  
  
  CONCLUSIONS
  Ionizing radiation in the absence and presence of simulated hypogravity results in acute lymphocyte dysfunction and compromised immune response.
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Jenine K
authors.initials: JK
authors.lastname: Sanzari
authors.forename: Jolaine M
authors.initials: JM
authors.lastname: Wilson
authors.forename: Erika B
authors.initials: EB
authors.lastname: Wagner
authors.forename: Ann R
authors.initials: AR
authors.lastname: Kennedy
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005434:Flow Cytometry; D008213:Lymphocyte Activation / Q000528:radiation effects; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D011833:Radiation Injuries, Experimental; D011839:Radiation, Ionizing; D051381:Rats; D013154:Spleen / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D013997:Time Factors