Host factors and susceptibility to influenza A infection: the effect of ABO blood groups and HL-A antigens.

The effect of two host genetic factors on the outcome of influenza A infections has been examined, ABO blood groups and HL-A antigens. A significantly higher proportion of blood group B subjects was found to have serological evidence of infection with epidemic influenza despite a high incidence of residual antibody among the volunteers. No difference was observed in the ability of subjects of different blood groups to seroconvert after receiving two doses of live attenuated influenza A vaccine, but a significantly higher proportion of blood group A vaccines seroconverted after receiving their first dose of vaccine. The association between HL-A type BW16 and resistance to infection with influenza could not be confirmed. The results are discussed in terms of an indirect association between susceptibility to influenza infection and the two host genetic factors.