MHC II on transfused murine blood is not required for alloimmunization against MHC I.
OBJECTIVE
Transfusion of allogeneic platelet products can result in antibodies against donor major histocompatibility complex (MHC) I antigens, leading to a refractory state to subsequent platelet transfusions. However, there is disagreement in the field regarding the molecular mechanisms of humoral alloimmunization. One hypothesis states that donor MHC II is a requirement for alloimmunization. However, other studies have suggested that donor MHC I is alone sufficient and MHC II is not required.


METHODS
We utilized a mouse model of anti-MHC I alloimmunization to transfused blood, which employed donors with a complete deletion of all MHC II genes. BALB/c (H-2(d)) recipients were transfused with blood from either C57BL/6 (H-2(b)) or MHC II null donors on a C57BL/6 background. Anti-MHC I alloimmunization was monitored by indirect immunofluorescence.


RESULTS
Recipients of either wild type or MHC II null blood produced equivalent humoral responses against donor MHC I antigens. However, there was variation in the relative amounts of IgG subclasses.


CONCLUSIONS
These data reject the hypothesis that donor MHC II expression is required for alloimmunization to MHC I antigens.
Gilson
C R
CR
Center for Transfusion and Cellular Therapies, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, USA.
Cadwell
C M
CM
Smith
N H
NH
Hendrickson
J E
JE
Zimring
J C
JC
D000017:ABO Blood-Group System; D000818:Animals; D005700:Galactosyltransferases / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D017713:Platelet Transfusion
D000017:ABO Blood-Group System; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; C427751:Abo protein, mouse; D005700:Galactosyltransferases