T cell mixed chimerism is significantly correlated to a decreased risk of acute graft-versus-host disease after allogeneic stem cell transplantation.
BACKGROUND
It has been debated whether mixed chimerism (MC) is correlated to a decreased incidence of graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (SCT).


METHODS
Between September 1996 and April 1999 we analyzed 102 patients for MC in the T-cell fraction post allogeneic SCT, using PCR amplification of variable numbers of tandem repeat (VNTR) loci. All samples, taken regularly post SCT, were cell separated using anti-CD3 immunomagnetic beads.


RESULTS
T-cell mixed chimerism was detected in 58 out of 102 patients (57%). Patient characteristics were comparable in the T-cell MC- and donor chimeric-group (DC). The median follow-up time for the MC group was 714 days (range 58 - 1248) as compared to 427 days (range 45 - 1042) for the DC group. Overall probability of acute GVHD grades II-IV was significantly higher in the DC group as compared to the MC group (52% vs. 5%, P<0.001). In multivariate analysis T-cell DC proved to be the most significant risk factor for acute GVHD grades II-IV. The cumulative incidence of relapse, among patients with malignant disease, did not show any statistical difference between the T-cell MC patients and the DC-group. There was a tendency for better overall survival in the T-cell MC group compared to the DC group (2 yrs; 73% vs. 54%, P=0.06). Among DC patients, 14/20 (70%) deaths were due to GVHD versus none in the MC-group(P<0.001).


CONCLUSIONS
T-cell mixed chimerism was significantly correlated to a decreased risk of moderate to severe acute GVHD and death by GVHD.
Mattsson
J
J
Centre for Allogeneic Stem Cell Transplantation and Department of Clinical Immunology, Karolinska Institute, Huddinge Hospital, Sweden.
Uzunel
M
M
Remberger
M
M
Ringdén
O
O
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006086:Graft vs Host Disease / Q000453:epidemiology* / Q000209:etiology* / Q000401:mortality; D018380:Hematopoietic Stem Cell Transplantation / Q000009:adverse effects*; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012307:Risk Factors; D015996:Survival Rate; D013601:T-Lymphocytes / Q000502:physiology*; D018183:Transplantation Chimera