Autolymphocyte therapy —I. In vivo tumour-specific adoptive cellular therapy of murine melanoma and carcinoma using ex vivo activated memory T-lymphocytes

Autolymphocyte therapy (ALT) is tumour-specific adoptive cellular therapy of neoplastic disease based upon non-specific ex vivo activation of autologous peripheral blood lymphocytes (PBL), using the supernatant derived from a previously prepared one-way mixed lymphocyte culture (MLC). To determine the requirement for tumour antigen during the activation process, splenocytes from C57BL/6J healthy syngeneic mice (HSM) and tumour-bearing mice (TBM) were activated ex vivo using a MLC-supernatant (MLCS). Ex vivo activation was performed both in the presence (HSM splenocytes) and absence (TBM splenocytes) of a 3M KCI syngeneic tumour-antigen (STA) extract prepared from Lewis lung (3LL) carcinoma, B16 melanoma, or normal lung. Immunophenotyping of splenocytes pre- and post-activation by MLCS plus STA or MLCS only revealed expansion of activated CD44(+) (memory) T-cells. Ex vivo tumour-specific cytotoxicity was demonstrated using MLCS-activated (TBM) or MLCS + STA-activated (HSM) splenocytes against 3LL or B16 target cells. CD44(+) T-cells (ALT-cells) were then infused into syngeneic 3LL and B16 TBM. Significant antitumour activity was detected in 3LL and B16 TBM receiving cells from normal mice that were activated with MLCS in the presence of 3LL or B16 STA, respectively, and in 3LL and B16 TBM receiving splenocytes from 3LL-TBM and B16-TBM, respectively, activated by MLCS alone. Infusions of 3LL-derived or B16-derived ALT-cells into HSM provided specific immunity on tumour challenge. No antitumour activity was seen in 3LL and B16 TBM receiving fresh TBM splenocytes, ALT-cells derived from HSM which were activated ex vivo using MLCS without antigen, normal lung tissue as antigen, or using MLCS-activated splenocytes without STA derived from reciprocal TBM. Ex vivo depletion of CD44(+) cells or Thy-1.2(+) T-cells abrogated all antitumour activity in TBM and in HSM challenged with tumour. Depletion of NK-1.1(+) natural killer (NK)-cells had no effect on antitumour efficacy. These data suggest that tumour-specific adoptive cellular therapy is possible using ex vivo activated HSM splenocytes with STA, or TBM splenocytes activated ex vivo without STA, and that these antitumour effects are dependent on CD44(+) memory T-cells.