The immune response is subject to individual variability at all levels

All the components of the immune system involved in recognition and memory and in the nature, vigour and distribution of responses to antigenic challenge may be affected by the genotype and phenotype of the exposed person. They are likely to be greatly influenced by the individual genotype as well as by phenotype effects, and so are likely to vary greatly between individuals, depending on constitutional factors and on any previous exposure of the individual. Although immune responses do follow conventional types of dose-response relationship, the end effect is greatly modified by prior sensitisation. There is a considerable range of individual responses in conditions involving the immune system, as is well shown in the variability of the common immunological disorders of asthma and contact dermatitis, although strong sensitisers may be able to overcome much of the difference in the responsitivity of the individual.