Relative roles of natural killer- and T cell-mediated anti-leukemia effects in chronic myelogenous leukemia patients treated with interferon-alpha.
Potential anti-leukemia effects mediated by T cells or by natural killer (NK) cells were investigated in chronic myelogenous leukemia (CML) patients treated with interferon-alpha. Therapy-associated modulation of T cell and NK reactivity was monitored for one year from initiation in autologous mixed lymphocyte-tumor cell reactions and cytotoxicity directed against autologous CML cells, respectively. During the course of IFN-therapy, NK activity against autologous CML cells increased steadily, whereas T cell reactivity fluctuated randomly. Despite the high level of T cell reactivity to autologous tumor cells in short-term (6 days) culture, 1) they failed to respond to synthetic peptides corresponding to the bcr/abl fusion sequence of the patient, and 2) only one proliferative T cell clone (TCC) was isolated which specifically recognized HLA-DR-matched CML cells. This TCC appeared not to recognize synthetic peptides corresponding to the bcr/abl fusion sequence of the patient; the antigen to which it responds remains unknown. To assess potential immunogenicity of bcr/abl peptides, it was attempted to sensitize T cells from normal donors in vitro. Of 109 cell lines obtained from seven different donors, eleven showed peptide-dependent proliferation. Therefore, although these results show that it is possible to isolate apparently CML-specific T cells from patients, as well as to prime T cells against tumor-specific peptide in vitro, the frequency of such T cell-mediated reactivity appears low and its relevance to anti-leukemic effects questionable. On the other hand, the strong time-dependent enhancement of natural killing of autologous CML blasts during IFN-alpha treatment, a phenomenon not observed for T cell reactivity, suggests that natural immunity may be more important in controlling disease.
Section for Transplantation Immunology and Immunohematology, University of Tübingen, Germany.
G
G
Pawelec
P
P
Da Silva
H
H
Max
H
H
Kalbacher
H
H
Schmidt
O
O
Bruserud
U
U
Zügel
W
W
Baier
A
A
Rehbein
H
H
Pohla
D000595:Amino Acid Sequence; D016044:Fusion Proteins, bcr-abl / Q000276:immunology; D006801:Humans; D016898:Interferon-alpha / Q000008:administration & dosage*; D007376:Interleukin-2 / Q000008:administration & dosage*; D015979:Killer Cells, Lymphokine-Activated / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology*; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000276:immunology; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D016898:Interferon-alpha; D007376:Interleukin-2; D010455:Peptides; D016044:Fusion Proteins, bcr-abl