Combination chemo-immunotherapy: kinetics of in vivo and in vitro generation of natural killer cells and lymphokine-activated killer cells in the rat.
Rats received a single high dose of cyclophosphamide (Cy) (150 mg/kg), followed 48 h later (on day 0) by immunization with a T cell-dependent soluble antigen, ovalbumin in Freund's complete adjuvant (FCA). The effect of this treatment on lymphoid cell subpopulations in the spleen, natural killer (NK) cell and interleukin-2 (IL-2) induced lymphokine-activated killer (LAK) cell activity was examined. Cy (with and without ovalbumin) caused a large relative increase (by day 14) in splenic OX8+, OX19- cells with NK morphology. A marked relative increase in fresh NK cell activity was noted after Cy + ovalbumin, but not consistently after Cy alone. Elevated NK activity was Cy dose- and time-dependent, was evident within 7 days post Cy/ovalbumin and persisted for at least 28 days. Pooled splenic mononuclear cells (MNC), obtained 14 days after Cy/ovalbumin, lost all cytolytic activity against YAC-1 cells when cultured in the absence of human recombinant IL-2 (rIL-2). In contrast, similarly maintained cells from normal rats displayed NK activity higher than normal 'fresh' levels. Upon culture in medium containing 500 U/ml rIL-2, however, 'augmented' NK activity was equivalent, on a per-cell basis, in both normal and Cy/ovalbumin-pretreated groups. LAK activity generated in vitro (i.e. against NK-resistant target cells) was significantly lower in the latter group, and the overall yield of cells was reduced. By day 21 after Cy/ovalbumin, augmented NK activity was significantly greater than controls, on a per-cell and total culture yield basis. Moreover, LAK activity was now similar between groups. It is concluded that the chemotherapy/immunization protocol which we have used can greatly enhance NK activity in vivo and that these cells are responsive to induction of LAK activity by IL-2 in vitro.
Stewart
L S
LS
Department of Pathology, University of Aberdeen, UK.
Sewell
H F
HF
Thomson
A W
AW
D000818:Animals; D002478:Cells, Cultured; D003131:Combined Modality Therapy; D003520:Cyclophosphamide / Q000008:administration & dosage / Q000494:pharmacology*; D007376:Interleukin-2 / Q000494:pharmacology; D015979:Killer Cells, Lymphokine-Activated / Q000187:drug effects*; D007694:Killer Cells, Natural / Q000187:drug effects*; D007700:Kinetics; D007958:Leukocyte Count; D008297:Male; D010047:Ovalbumin / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011994:Recombinant Proteins / Q000494:pharmacology; D013154:Spleen / Q000276:immunology
D007376:Interleukin-2; D011994:Recombinant Proteins; D003520:Cyclophosphamide; D010047:Ovalbumin