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We consider the problem of self tolerance in the frame of a minimalistic model of the<br/>idiotypic network. A node of this network represents a population of B lymphocytes of the<br/>same idiotype which is encoded by a bit string. The links of the network connect nodes<br/>with (nearly) complementary strings. The population of a node survives if the number of<br/>occupied neighbours is not too small and not too large. There is an influx of lymphocytes<br/>with random idiotype from the bone marrow. Previous investigations have shown that this<br/>system evolves toward highly organized architectures, where the nodes can be classified<br/>into groups according to their statistical properties. The building principles of these<br/>architectures can be analytically described and the statistical results of simulations<br/>agree very well with results of a modular mean-field theory. In this paper we present<br/>simulation results for the case that one or several nodes, playing the role of self, are<br/>permanently occupied. These self nodes influence their linked neighbours, the autoreactive<br/>clones, but are themselves not affected by idiotypic interactions. We observe that the<br/>group structure of the architecture is very similar to the case without self antigen, but<br/>organized such that the neighbours of the self are only weakly occupied, thus providing<br/>self tolerance. We also treat this situation in mean-field theory which give results in<br/>good agreement with data from simulation. The model supports the view that autoreactive<br/>clones which naturally occur also in healthy organisms are controlled by anti-idiotypic<br/>interactions, and could be helpful to understand network aspects of autoimmune<br/>disorders.