Femur fracture induces site-specific changes in T-cell immunity.
BACKGROUND
Trauma is associated with altered host defense and susceptibility to infection, in part due to cytokine dysregulation and altered T-cell immunity. The gut-associated lymphoid tissue (GALT) provides a defense against infection and contributes to the process of mucosal healing by T-cell activation and cytokine production.


OBJECTIVE
To determine whether femur fracture induces alterations in Peyer's patch and splenic T-cell phenotype, proliferative response, and cytokine expression following traumatic injury.


METHODS
Mice underwent femur fracture or sham procedure and, 48 h later, lymphocytes were isolated from spleen and Peyer's patches. Lymphocytes were cultured, and lipopolysaccharide (10 microg/ml) was added in some cultures. Cells and supernatant were harvested at 48 h. Proliferation was analyzed by [3H]thymidine, and interleukin-10 (IL-10) protein was measured by ELISA in the culture supernatant. T-cell phenotype was determined by flow cytometry.


RESULTS
Femur fracture induced a significant increase in proliferative response in Peyer's patch immunocytes. In contrast, no significant differences were identified in splenocyte proliferative response 48 h after femur fracture injury. Femur fracture induced a significant decrease in IL-10 protein expression of both splenocytes and Peyer's patches. Femur fracture also induced a significant increase in the fraction of CD3(+), CD4(+), and T-cell receptor-alpha beta Peyer's patch immunocytes, whereas splenocytes demonstrated no significant phenotypic change.


CONCLUSIONS
Femur fracture is associated with significant alterations in Peyer's patch but not splenic T-cell phenotype and proliferative response early (48 h) after injury. Changes in the GALT immune response may contribute to intestinal mucosal dysfunction and increased susceptibility to gut-derived sepsis after traumatic injury.
Buzdon
M M
MM
Department of Surgery, Baltimore VA Medical Center, Baltimore, Maryland, 21201, USA.
Napolitano
L M
LM
Shi
H J
HJ
Ceresoli
D M
DM
Rauniya
R
R
Bass
B L
BL
D000818:Animals; D002455:Cell Division; D005264:Femoral Fractures / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D007109:Immunity; D016753:Interleukin-10 / Q000378:metabolism; D008214:Lymphocytes / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010581:Peyer's Patches / Q000473:pathology; D010641:Phenotype; D013154:Spleen / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology* / Q000502:physiology
D016753:Interleukin-10