It is possible that the independent association between increased IL-10 TT responses and household socio-economic status might be mediated by repeated, unmeasured, exposures to infection. Consistently lower responses were seen in girls. This shows that gender differences in immune response are present at an early age, and could be related to reported gender differences in the non-specific effects of immunisation on infant mortality [49]. learn more This study examined factors influencing the cytokine responses induced by BCG and tetanus immunisation, not their

efficacy. In the case of BCG, it is likely that IFN-γ is required, although not sufficient for, protective immunity [15], while excessive production of type 2 cytokines may be detrimental [50]. Excess production of IL-10 may also be detrimental, if it is associated with suppression of protective responses, but evidence from the mouse model suggests that adequate production may be required to prevent a pathological, inflammatory response [51]. Follow up of the cohort is in progress to determine how the observed responses are related to rates Microtubule Associated inhibitor of M. tuberculosis infection and disease. In the case of tetanus

immunisation, the induction of neutralising antibody is key to protective immunity [52]; the relationship between observed effects on cytokine responses and the production of antibody will be the subject of further investigation.From a public health perspective, TCL our results demonstrate strong effects of current, or recent infant infections on the infant response to vaccine antigens, and reinforce the importance of control and treatment of malaria and HIV infection for the immunological health of mothers and their children; but suggest that maternal helminth infection may have little, if any, adverse effect on the outcome of infant immunisation. Immunisation during pregnancy may

enhance the infant response to selected vaccines, and this, as well as the role of prior maternal BCG immunisation and mycobacterial infection in determining the infant response to BCG immunisation, needs to be explored in further research. We thank all staff and participants of the Entebbe Mother and Baby Study, the midwives of the Entebbe Hospital Maternity Department, the community field team in Entebbe and Katabi, and the staff of the Clinical Diagnostic Services Laboratory at the MRC/UVRI Uganda Research Unit on AIDS. We thank Dr. Stephen Cose for critical review of the manuscript. The study was funded by Wellcome Trust grant numbers 064693 and 079110; mycobacterial antigens were provided through the National Institutes of Health contract NOI-AI-25147. Conflict of interest: James Whitworth is now a member of staff with the Wellcome Trust, the funders of the study. His role in the initial design and conduct of the study preceded his appointment at the Wellcome Trust. He has had no role in the study since his appointment.