Abstract: |
It is difficult to avoid the feeling that we usually discuss only the obvious, since the conclusion reached after this uncoordinated effort is that normal ontogeny (of a function, such as T cells) would tell us something about abnormal ontogeny, but it may not tell us much about normal or abnormal adult functions (such as the maintenance of the T cell pool). This was also stated in the brief introductory passage to this review. I tried to trace the origin of the idea that the study of the development of the first cohort of T cells will tell us how the system works and maintains itself in the adult, but could not find anyone directly responsible for it, and that could be blamed. However, it is a pervading notion, which is probably wrong. The mechanisms for constant renewal of T cells in the adult are probably quite different from those operative during the initial development of the T cell system in the embryo, and certainly ontogeny is not the mirror image of the age-related decline of immune functions, although some similarities may be apparent. The peculiar regulation of immune functions during early ontogeny may be related to the need to control potentially aggressive maternal cells, as well as be part of the overall interactive regulatory mechanisms of the immune system. |