The invention provides methods of preparing tumor infiltrating cells engineered to express a pro-inflammatory polypeptide. The pro-inflammatory polypeptide is expressed from the tumor infiltrating cell to counter a generally immunosuppressive state in and around tumors resulting from an imbalance between the number and activation state of immune effector cells versus those of suppressor cells. Delivering the proinflammatory polypeptide via expression from the TICs, as distinct from systemic administration, reduces side effects from increased inflammation at sides remote from a tumor to be treated.本發明提供製備經工程化以表現促發炎多肽之腫瘤浸潤細胞之方法。該促發炎多肽係由該腫瘤浸潤細胞表現,以逆轉由免疫效應細胞之數量及活化狀態相對於抑制細胞之數量及活化狀態間之失衡引起之腫瘤內及腫瘤周圍之一般免疫抑制狀態。經由TIC之表現遞送該促發炎多肽明顯不同於全身投與,可減少在遠離欲治療腫瘤之部位因發炎增加所致之副作用。