Vaccine-induced antibody responses as parameters of the influence of endogenous and environmental factors

In laboratory animals, an adequate way to assess effects of environmental e xposures on the immune system is to study effects on antigen-specific immun e responses, such as after sensitization to T-cell-dependent antigens. This probably also applies to testing effects in the human population. It has t hus been suggested that antibody responses to vaccination might be useful i n this context. Vaccination responses may be influenced by a variety of fac tors other than environmental ones. One factor is the vaccine itself; a sec ond is the vaccination procedure used. In addition, the intrinsic capacity of the recipient to respond to a vaccine, which is determined by sex, genet ic factors, and age, is important. Psychological stress, nutrition, and (in fectious) diseases are also likely to have an impact. We reviewed the liter ature on vaccine response. With regard to exogenous factors, there is good evidence that smoking, diet, psychological stress, and certain infectious d iseases affect vaccination titers, although it is difficult to determine to what extent. Genetic factors render certain individuals nonresponsive to v accination. In general, in epidemiologic studies of adverse effects of expo sure to agents in the environment in which vaccination titers are used, the se additional factors need to be taken into consideration. Provided that th ese factors are corrected for, a study that shows an association of exposur e to a given agent with diminished vaccination responses may indicate subop timal function of the immune system and clinically relevant diminished immu ne response. It is quite unlikely that environmental exposures that affect responses to vaccination may in fact abrogate protection to the specific pa thogen for which vaccination was performed. Only in those cases where indiv iduals have a poor response to the vaccine may exogenous factors perhaps ha ve a clinically significant influence on resistance to the specific pathoge n. An exposure-associated inhibition of a vaccination response may, however , signify a decreased host resistance to pathogens against which no vaccina tion had been performed.