Tumour-bearing animals synthesize a decreased level of mRNA for the inducible 55,000 MW interleukin-2 receptor.

Spleen cells from mice bearing progressive growing methylcholanthrene-induced syngenic tumours were deeply hyporeactive in response to T-cell mitogens. This hyporeactivity was associated with decreased ability to synthesize mRNA for the inducible 55,000 MW interleukin-2 receptor (IL-2R). Since the expression of functional IL-2R represents one of the early and pivotal events in lymphoid-cell activation, it is suggested that the defect in effective IL-2R expression may be one of the primary factors responsible for the immunological hyporeactivity of tumour-bearing hosts.