Cytotoxic lymphocyte (CTL) effector genes expression in bronchoalveolar lavage (BAL) of lung transplant (LTx) patients during CMV infection versus acute rejection (AR).

Abstract

170 Introduction: Differential diagnosis between AR and CMV infection remains difficult in lung transplantation. Activated T lymphocytes play a major role in both pathologies. Proteins expressed only in CTL such a granzyme B (GB), perforin (P), and fas-ligand (Fas-L), together with granulysin (GL) are responsible for CTL mediated immunity. On the other hand, interleukin-15 (IL-15) promotes T cell and NK-cell proliferation and appears to be synthesized early in viral infection. The aim of our study was to prospectively evaluate the mRNA expression of GB, P, Fas-L, GL and IL-15 in BAL specimens of LTx patients. Methods: 15 cc of BAL fluid were collected from LTx patients who underwent bronchoscopy (with BAL and biopsy) at SUMC between 2/97 and 7/98. Cell pellets were immediately processed for mRNA extraction. RT and competitive template PCR was carried out as previously described. Results were calculated as a ratio of the amount of gene transcript detected divided by the amount of GAPDH detected. Results: (see table) P, Fas-L and GL mRNA expression were respectively 2.3 (p=0.01), 3.8 (p=0.02), and 6.8 (p=0.03) times higher in CMV infection as compared to AR. Moreover, Fas-L and P mRNA expression showed respectively a 5 fold (p=0.024) and a 7 fold (p=0.002) increase in CMV infected patients as compared to patients with no significant pathology (NSP). GL mRNA expression was 2.83 times higher (p=0.07) in non-CMV infected (INF) patients as compared to CMV infected patients. Analysis of GL and the CTL effector genes revealed a significant difference (p=0.003) between cystic fibrosis (CF) patients (n=16) as compared to non-CF patients (n=35), regardless of the clinical diagnosis at the time of BAL. IL-15 was not significantly different amongst the samples but tended to be higher in the presence of infection. (* significant at p<0.05 as compared to AR)TableConclusion: Expression of the CTL effector genes (GB, P, Fas-L) and GL in BAL of LTx patients is increased in patients with CMV infection as compared to patients with AR. Regardless of the underlying diagnosis (NSP, AR, CMV or non-CMV infection), the BAL of CF-LTx patients revealed a higher expression of GB, P, Fas-L and GL as compared to that of non-CF LTx patients.