Vaz NM, Faria AMC, Verdolin BA, Carvalho CR. Immaturity, Ageing and Oral Tolerance. Scand J Immunol 1997;46:225-229 Founding studies of cellular immunology emphasized that tolerance to allografts could only be achieved early in the embryonic or neonatal period, suggesting that the establishment of self-tolerance, a main event in the organization of the immune system, would necessarily take place in immature hosts. Contradicting these ideas, oral tolerance is a common, daily phenomenon, easily achieved by a physiological route in adult immunocompetent animals. Furthermore, there is solid evidence that, after the neonatal period, the susceptibility to oral tolerance induction also wanes and that it may be restored by adoptive transfer of cells from young hosts. These findings are briefly reviewed here to emphasize that immunological activity is a continuous and ongoing epigenesis extending throughout the entire life of the organism, far beyond the early phases of ontogenesis.
Nelson M. Vaz, Department of Biochemistry and Immunology, CP 486, Instituto de Ciências Biológicas, Universidade Federal de Minas Gevais 30161-970, Belo Horizonte, MG, Brazil
THE DOMINANT IMMUNOLOGICAL PARADIGMWe refer to the 'dominant immunological paradigm' [1] as a large interlaced set of terms and notions based on the concept of specific immunological recognition of foreign epitopes (immunity) and its complement, the notion of self-tolerance (self/nonself discrimination). The current version of the paradigm is based in different versions of the Clonal Selection Theory of Antibody Formation [2]. An alternative paradigm should be able to define, discuss and explain immunological activities and immunological phenomena without relying on the distinction between foreign and familiar materials (self/non-self discrimination) or on the notion of self-tolerance (self-ignorance). Up to this moment, we are not aware of such an alternative being fully formulated.In a previous essay [3], we pointed to a confusion of domains of description inherent to the current paradigm, which confounds the structural dynamics of the immune system (its physiology) with immunological phenomena (such as specific immune responses) which take place in the domain of interactions of the organism acting as a whole 1 . In the present essay, we use the same way of seeing to describe the set of phenomena currently described as 'oral tolerance'. We will show that these phenomena are not explained by the current paradigm and require alternative systemic notions to explain them.
SELF-TOLERANCE AND IMMATURITYCreated in the early 1960s, the current immunological paradigm was heavily influenced by experimental findings on bovine twins' natural allogeneic chimeras [4], the rejection of allografts in mice [5,6] and chickens [7,8] and the adoptive transfer of immunological competence by lymphocytes [9][10][11][12]. The Clonal Selection Theory hinged around the notions of self/non-self discrimination (self-tolerance) already emphasized in a previous book by Burnet & Fenner [13], exp...