Central lymphoid tissues nervous system

Cancer is uncommon during the first two decades of life, but is nonetheless a substantial concern. In the United States, cancer is diagnosed in approximately 12 400 children and adolescents annually and is the most common cause of death from any kind of disease between 1 and 19 years of age. In the United States and other developed countries, lymphoid neoplasms (leukaemia, lymphoma) and cancers of the central nervous system are the most common paediatric malignancies. Other kinds of childhood tumours include embryonal tumours of the retina, sympathetic nervous system, kidney, and liver tumours of bone and soft connective tissues and certain gonadal neoplasms. Different kinds of cancer (e.g. carcinomas of liver or thyroid) may predominate in children in parts of the world where specific environmental risk factors are more prevalent. 

The studies reviewed in this chapter demonstrate that a strong and reciprocal relationship exists between the central nervous system and the immune system. Indeed, the term neuroim-mune system is clearly justified and appropriate to emphasize the fact that nervous and lymphoid tissues constitute a unified system that functions in the maintenance of homeostasis. The conventional division between the two systems has blurred, as well as the distinction between neuropeptides on the one hand, and immune cytokines on the other. Two lines of research have altered our perspective on neuroimmune interactions (a) the identification of conventional neuropeptides and then-receptors, especially those related to the HPA axis, in most lymphoid tissues, and (b) the large body of evidence that cytokines, historically associated with immune system communication, play vital roles in nervous function. 

In cases where Fc receptors in the tissue are a problem (cells of the lymphoid system, central nervous system and some epithelia) the use of Fab may offer a solution. Pretreatment of the samples with 2% normal serum may also obviate this problem. 

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