SIGNIFICANCE OF HUMAN CYTOMEGALOVIRUS DNA DETECTION IN IMMUNOCOMPROMISED HEART-TRANSPLANT PATIENTS

Peripheral blood samples (n=1240), obtained at variable intervals from 483 heart transplantation (HTx) patients under immunosuppressive ther apy, and blood samples (n=1013) obtained upon blood donation from 1013 healthy anti-human cytomegalovirus (HCMV) positive blood donors, were tested for HCMV DNA by nested polymerase chain reaction (PCR). The de tection limit of the nested PCR was determined to be less than 10 copi es of the plasmid pRR 47, containing the HCMV immediate early gene. HC MV DNA was detected in 79 of 483 HTx patients (17%). To the contrary, HCMV DNA was only detected in 1 of 1013 anti-HCMV positive, healthy bl ood donors (0.1%). This PCR positive donor had recently contracted a p rimary HCMV infection. The rate of HCMV PCR positive immunosuppressed HTx patients in our study was lower than the rate of HCMV PCR positive healthy blood donors in previous reports in the literature. Blood sam ples (269 from 117 HTx patients) were assayed for HCMV DNA in peripher al blood leukocytes, HCMV DNA in plasma, and HCMV tegument protein 65 kDa (pp 65 antigen). Three laboratory diagnostic patterns were observe d and related to clinical findings: (1) HCMV DNA only in leukocytes wa s observed in 26 patients, 7 of whom had HCMV disease, 5 of whom had g raft rejection, and 14 of whom had no specific symptoms; (2) HCMV DNA both in leukocytes and in plasma (viremia) was observed in 3 patients, who were all symptomatic with HCMV disease; (3) HCMV DNA in leukocyte s and in plasma (viremia) and pp 65 antigen were observed in 13 patien ts, all of whom were symptomatic (10 patients had HCMV disease, and 3 patients had graft rejection). A similar sequence of diagnostic patter ns was observed in all symptomatic HCMV infections and reactivations i n this study: HCMV DNA appeared first ire peripheral blood leukocytes, then also in plasma, followed by pp 65 antigen detectable in peripher al blood leukocytes. Upon clinical recovery, these findings disappeare d in reverse order. However, HCMV DNA remained detectable in periphera l blood leukocytes for several weeks. The detection of HCMV DNA in the peripheral blood is an exception, not the rule, even in severely immu nosuppressed HTx patients. It indicates a pathological condition, albe it without clinical symptoms in some patients, and it is the earliest signal of HCMV replication. Of 42 patients in whom HCMV DNA was initia lly detected only in peripheral blood leukocytes, 16 patients progress ed into viremia. Thus, HCMV-specific PCR performed on nucleic acid ext racts from lysed peripheral blood is an appropriate method for the mon itoring of HCMV infections in immunosuppressed HTx patients.