Differential in situ expansion and gene expression of CD4+ and CD8+ tumor-infiltrating lymphocytes following adoptive immunotherapy in a murine tumor model system
✍ Scribed by Robert Evans; Theodore M. Duffy; Sonya J. Kamdar
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 584 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0014-2980
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✦ Synopsis
Abstract
In previous reports, we demonstrated that adoptively transferred T cells homed to the tumor site (among other sites) and that amplification of immune responses occurred in situ leading to the generation of cytotoxic CD8^+^ tumor‐infiltrating lymphocytes (TIL) and macrophages. The present report extends these findings and shows that following adoptive immunotherapy (AIT) of mice bearing the immunogenic transplanted methylcholanthrene‐induced rhabdomyosarcoma (MCA/76‐9) there was a differential expansion of CD4^+^ and CD8^+^ TIL, the numbers peaking on days 6 and 8, respectively. At this time, CD8^+^ TIL accounted for the majority of Thy‐1^+^ cells. Northern analyses of RNA extracted from positively selected (by panning) Thy‐1^+^, CD8^+^ and CD4^+^ TIL isolated 8 days after AIT indicated the following: in five separate experiments, CD4^+^ cells expressed three‐ to sixfold more interleukin (IL)2 mRNA and six‐ to eightfold more IL6 mRNA than CD8^+^ cells, while CD8^+^ TIL expressed three‐ to sixfold more IL 2 receptor (IL 2R) mRNA and four‐to sixfold more interferon‐γ mRNA than CD4^+^ cells. TIL cultured in 10% fetal bovine serum failed to release IL2 over a 24‐h period, whereas both IL6 and interferon‐γ activities were demonstrable. The level of IL2R mRNA expression was reflected by a vigorous proliferative response of CD8^+^ TIL to exogenous recombinant IL2 and only a low response by CD4^+^ cells suggesting that most of the CD4^+^ TIL were in the resting stage. This was confirmed when it was shown that the incubation of panned CD4^+^ TIL with IL2 supplemented with irradiated spleen cells and “spent” 76‐9 tumor culture supernatant (as a source of antigen) induced expansion of TIL resulting in a population consisting of >90% CD4^+^ TIL. The overall data suggest that the relatively deactivated state of the CD4^+^ TIL at this particular time reflects the status of the rejection process in terms of the absence or low concentration of stimulating tumor‐associated antigen.