Key Words: Immunology, adult stem cells, vaccines.Hypothesis driven, fundamental studies of murine and human immunology. Two major topics are addressed: 1) How do adult mesenchymal stem cells modulate immunity (a question with implications for stem cell therapy, transplantation and tolerance); 2) The immunology of early life, particularly at the mucosal surface of the airways. This has led me to examine early life infections with the pathogens B. pertussis, poliovirus and B19V, work which has implications for vaccine design immunization and diagnostics. When appropriate, work has been commercialized. Key recent advances: a) new insights into how adult stem cells modulate immunity b) a clinical trial of a new whooping cough vaccine in 2010.