T cell depletion with anti-CD5 immunotoxin in histocompatible bone marrow transplantation. The correlation between residual CD5 negative T cells and subsequent graft-versus-host disease.
Twenty-nine patients with advanced leukemias (median age 34 years) received histocompatible sibling marrow that had been depleted of T cells by ex vivo incubation with anti-CD5 monoclonal antibody-ricin immunotoxin (T101-R) for the purpose of graft-versus-host disease prophylaxis. Donor cell engraftment was documented in 28/29 patients by DNA restriction fragment length polymorphisms. In this pilot study the dose of T101-R incubated with donor marrow was increased in a stepwise manner from 300 ng (10 patients) to 600 ng (5 patients) to 1000 ng immunotoxin (IT)/10(7) bone marrow mononuclear cells (14 patients) in an attempt to achieve more effective GvHD prophylaxis. A statistically significant reduction in acute GvHD was achieved for patients receiving marrow pretreated with 1000 ng of immunotoxin (34%) compared to recipients of BM treated with 300 ng immunotoxin (100%, P = 0.0004). T-depleted marrow samples were evaluated for residual T cell activity using several in vitro assays including proliferation to the purified mitogen PHA (HA-17) and in mixed lymphocyte culture (MLC), T cell cytotoxicity, a limiting dilution assay for detecting precursors of proliferating T cells (LDApPTL), and phenotypic analysis of viable T cells expanded in 16-day culture with interleukin 2. The extent of T cell depletion determined by LDA assay varied widely at each immunotoxin concentration used. Thus, there was no correlation between the dose of T cells infused and subsequent GvHD. Phenotyping of lymphocytes recovered from immunotoxin-treated marrow demonstrated that residual T cells were CD5 negative in all cases tested. The only in vitro parameter that predicted subsequent acute or chronic GvHD was the demonstration of viable CD5 negative lymphocytes with T cell phenotype (CD2, CD3, and/or CD7 positive) after 16-day culture with IL-2 of the T-depleted bone marrow. We observed that such CD5 negative cells expressing other T cell markers have cytotoxic function and speculate that these cells may be capable of mediating GvHD in allogeneic transplantation.
Filipovich
A H
AH
University of Minnesota, Minneapolis 55455.
Vallera
D
D
McGlave
P
P
Polich
D
D
Gajl-Peczalska
K
K
Haake
R
R
Lasky
L
L
Blazar
B
B
Ramsay
N K
NK
Kersey
J
J
D015703:Antigens, CD / Q000502:physiology; D000943:Antigens, Differentiation / Q000502:physiology*; D001854:Bone Marrow Cells; D016026:Bone Marrow Transplantation / Q000276:immunology*; D018956:CD5 Antigens; D003602:Cytotoxicity, Immunologic; D006084:Graft Rejection / Q000187:drug effects*; D006086:Graft vs Host Disease / Q000517:prevention & control*; D006680:HLA Antigens / Q000276:immunology; D006801:Humans; D000922:Immunotoxins / Q000627:therapeutic use*; D066298:In Vitro Techniques; D007376:Interleukin-2; D007694:Killer Cells, Natural / Q000276:immunology; D008212:Lymphocyte Depletion; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology
D015703:Antigens, CD; D000943:Antigens, Differentiation; D018956:CD5 Antigens; D006680:HLA Antigens; D000922:Immunotoxins; D007376:Interleukin-2