Characterization and activation requirements of bovine lymphocytes acquiring cytotoxic activity after interleukin-2 treatment.
Interleukin-2 (IL-2) treatment of cells and generation of non-major histocompatibility complex (MHC)-restricted cytotoxic cells from peripheral blood mononuclear leukocytes (PBML) was studied. Effector-target conjugate assays demonstrated that bovine PBML bound but did not lyse K562, HL60S and HL60R cells unless activated with IL-2. The magnitude of IL-2-activated killing of tumor cells as well as the magnitude of antibody-dependent cellular cytotoxicity depended on the IL-2 concentration. A short treatment (12-18 h) of effector cells with IL-2 was sufficient for development of cytotoxic activity. Withdrawal of IL-2 from the culture resulted in a reduction of cytotoxic activity that could be restored by further addition of IL-2. Cytotoxic activity of IL-2-activated populations obtained after nylon wool or Sephadex G-10 passage, and Percoll gradient centrifugation of PBML suggests that lymphokine-activated killer (LAK) cell activity in PBML is mainly mediated by a non-adherent lymphocyte lacking markers for B-cells. Positive and negative selection experiments using cell sorting confirmed these findings and demonstrated that the cell responsible for LAK cell activity in cattle belongs to a non-monocyte, non-B, CD2+ lymphocyte population. Furthermore, cytotoxic activity could not be generated in CD2+ populations enriched for cells expressing molecules equivalent to human and murine CD4 and CD8. These findings suggest that effector cells mediating non MHC-restricted cytotoxicity in cattle prevail in a population bearing a CD2+, CD4-, CD8- phenotype and that this population depends on the continuous presence of IL-2 for optimal cytotoxic function.
Veterinary Infectious Disease Organization (VIDO), University of Saskatechewan, Saskatoon, Canada.
M
M
Campos
C R
CR
Rossi
H
H
Bielefeldt Ohmann
T
T
Beskorwayne
N
N
Rapin
L A
LA
Babiuk
D000818:Animals; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology; D018801:CD2 Antigens; D002417:Cattle; D002469:Cell Separation / Q000379:methods / Q000662:veterinary; D003601:Cytotoxicity Tests, Immunologic / Q000662:veterinary; D005434:Flow Cytometry / Q000662:veterinary; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology*; D007694:Killer Cells, Natural / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects*; D011971:Receptors, Immunologic / Q000276:immunology; D014407:Tumor Cells, Cultured
D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D007376:Interleukin-2; D011971:Receptors, Immunologic