Subsets within alloreactive CTL (aCTL) exhibit upregulated proinflammatory cytokine secretion: aCTL response to coincubation with irrelevant and relevant parental and immunoresistant (IR) gliomas

Normal brain cells display little human leukocyte antigen (HLA), whereas gliomas do. Thus, aCTL sensitized to the HLA of the glioma patient target glioma cells upon intracranial administration. aCTL were analyzed by flow cytometry after 1‐way mixed lymphocyte reactions with inactivated patient stimulator and allogeneic responder lymphocytes. The CD3+/CD8+/CD69+ subsets expressed IFN‐γ at high mean fluorescence intensities (MFI) that greatly increased upon coincubation with relevant targets. Cytotoxicity assessments and cytokine panels obtained upon their coincubation with irrelevant and relevant glioma targets showed upregulated IL‐6 and IL‐8 secretions. To determine if the injury caused by the aCTL correlated with the levels of secreted IL‐6 and IL‐8, the parental glioma, two IR variants, and an irrelevant glioma were incubated with the aCTL. IL‐6 and IL‐8 release was upregulated more with the parental and IR glioma targets than the irrelevant target, even though the lysis of the irrelevant and IR variants approximated each other. Thus, the cytokine secretions do not necessarily translate into cell injury. Gliomas constitutively secrete IL‐6 and IL‐8. To determine if the gliomas or the aCTL contributed to the cytokine release, they were pretreated with brefeldin‐A prior to their coincubation. These experiments revealed that the aCTL were responsible for the IL‐6 and IL‐8 upregulations. Funded by NIH F31 CA94834 to GGG, NS‐046463 to CAK