Cytokine gene transcripts for tumor necrosis factor-alpha, interleukin-2, and interferon-gamma in human pulmonary allografts.

BACKGROUND: Cytokines participate in host responses to allografts, largely through recruiting and activating various regulatory and effector cells. We performed this study to determine the feasibility of using polymerase chain reaction methodology to define the expression of three important cytokines (tumor necrosis factor-alpha, interleukin-2, and interferon-gamma) in human pulmonary allografts.
METHODS: Twenty-six graft-derived samples (11 transbronchial biopsy and 8 macrophage and 7 lymphocyte cell pellets isolated from bronchoalveolar lavage) were obtained from 13 lung transplant recipients and treated as follows: extraction of RNA; reverse transcription of RNA to complementary DNA; polymerase chain reaction amplification of cDNA with oligonucleotide primers specific for the three cytokines; gel electrophoresis of the polymerase chain reaction products; and verification of correct cytokine message by Dot blot technique (with specific 32P-labeled oligonucleotide probes).
RESULTS: Concomitant pathologic evaluation of biopsy specimens from these 13 recipients showed five diagnostic groups: "normal" (no rejection/infection), n = 2; acute rejection, n = 4; nonspecific inflammation, n = 3; infection, n = 3; and obliterative bronchiolitis, n = 1. Interleukin-2 was expressed predominantly in acute rejection and infection (seven of ten and five of six samples positive, respectively), whereas tumor necrosis factor-alpha was expressed mainly in nonspecific inflammation (four of five samples) and somewhat less in rejection (six of ten). Interferon-gamma was expressed less frequently (in two of six samples with infection, but in none of ten with rejection and none of five with nonspecific inflammation). Serial data from one patient (6 months apart) showed considerable increase in interleukin-2 and interferon-gamma expression as she progressed from normal histologic status to obliterative bronchiolitis.
CONCLUSIONS: Cytokine gene transcripts can be determined from minute samples derived directly from pulmonary allografts. Although our data are insufficient to make definitive conclusions, the suggestion of trends of cytokine expression in different posttransplantation pathologic conditions may indicate a useful role for this approach in the clinical evaluation of the lung transplant recipient.