Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Because the process of granuloma formation sequesters and encapsulates bacteria but does not necessarily destroy them, mycobacteria may inhibit binding of phagosomes and avoid microbicidal activity, remaining protected from the immune system within the cell.(20,29) The disease may then be reactivated in times of relative immunosuppression, such as with systemic disease or immunosuppressive therapy.
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