QUANTITATIVE-ANALYSIS OF T-HELPER-1, T-HELPER-2, AND INFLAMMATORY CYTOKINE EXPRESSION IN PATIENTS AFTER ALLOGENEIC BONE-MARROW TRANSPLANTATION - RELATIONSHIP WITH THE OCCURRENCE OF ACUTE GRAFT-VERSUS-HOST DISEASE

Background. To further delineate the cytokine involvement in human acu te graft-versus-host disease (GVHD), we analyzed cytokine expression i n peripheral blood mononuclear cells (PBMC) from patients who develope d acute GVHD after allogeneic bone marrow transplantation and from tho se who did not. Methods. We used a highly quantitative and sensitive p olymerase chain reaction assay based on the coamplification of an inte rnal standard, with the cDNA derived from the mRNA of interest. Result s are expressed in copy numbers, after normalization to a fixed amount of actin, allowing comparison between different samples. After a myel oablative regimen, 22 patients with hematological diseases received an unmanipulated allograft from a matched sibling. They were subsequentl y submitted to prophylactic immunosuppression. We examined the transcr iption of genes encoding cytokines in PBMC and skin biopsies. We selec ted T helper 1 (interferon ([IFN]gamma, interleukin [IL]-2), T helper 2 (IL-4, IL-10), and inflammatory (IL-1, IL-6) cytokines. Results. Fou r weeks after bone marrow transplantation, the bulk of the PBMC popula tion exhibited an increased expression of IL-1 and IL-6, with no major difference between GVHD(+) and GVHD(-) patients. In addition, althoug h IL-2 expression was not detected, increased levels of IFN gamma mRNA were observed in allografted patients, with higher levels in GVHD(+) patients. In skin biopsies sampled at the beginning of GVHD, although low expression of IL-1 and IL-6 could be observed, neither type 1 (IL- 2, IFN gamma) nor type 2 (IL-4, IL-10) cytokines could be detected. Co nclusions. These studies suggest that the occurrence of human GVHD doe s not seem to be clearly associated with a T helper 1-type cytokine pa ttern.