Anti-human leukocyte antigen antibodies, vascular C4d deposition and increased soluble c4d in broncho-alveolar lavage of lung allografts.

BACKGROUND: The hallmark of humoral rejection is the presence of subendothelial C4d in the allograft. A simultaneous determination of vascular C4d with soluble C4d in broncho-alveolar lavage fluid (BAL) and circulating anti-human leukocyte antigen (HLA) antibodies (HLA-Ab) has not been reported in lung transplantation. METHODS: Forty-two consecutive lung-transplant patients were included in this cross-sectional study. The presence and specificity of HLA-Ab was determined at the same frequency with transbronchial biopsies. Soluble C4d levels were measured by enzyme-linked immunosorbent assay in all 42 patients. In a subgroup of 32 patients with available timely matched paraffin-embedded tissue sections, the vascular C4d deposition was also assessed. RESULTS: The presence of HLA-Ab in 16 patients was associated with biopsy-proven acute rejection (10/16 vs. 3/16, P<0.01) and increased immunosuppression (13/16 vs. 4/16, P<0.005). Pulmonary function was also decreased in patients with HLA-Ab (mean forced expiratory volume in 1 second=49%) when compared with the control group (mean forced expiratory volume in 1 second=66%, P<0.05). Nine patients exhibited specific vascular C4d deposition and in eight of nine (89%) cases HLA-Ab were detected, versus 8 of 23 (35%) in C4d-negative patients (P<0.05). Soluble C4d in BAL was highly (>0.5 microg/mL) elevated in patients with HLA-Ab and vascular C4d and was moderately (0.2 microg/mL) increased in patients with antibodies but C4d-negative. In contrast, only a slight elevation of soluble C4d (<0.1 microg/mL) was detected in patients without HLA-specific antibodies. CONCLUSIONS: The association of HLA-specific antibodies with vascular C4d deposition and soluble C4d in BAL, in addition to the reduced pulmonary function, might constitute a diagnostic triad for antibody-mediated rejection in lung transplant patients.

HLA-specific antibodies are associated with high-grade and persistent-recurrent lung allograft acute rejection.

BACKGROUND: The impact of HLA-specific antibodies is not well established in the acute rejection of lung allografts. Acute rejection represents the most important risk factor for the development of chronic lung allograft dysfunction. METHODS: We analyzed the pattern of HLA antibodies before and after transplantation in 54 patients, and correlated our data with the presence and frequency of high-grade and persistent-recurrent acute rejection, during the first 18 post-operative months. The diagnosis of acute rejection was based on histologic International Society for Heart and Lung Transplantation (ISHLT)-published criteria. RESULTS: Ten of 54 patients had a positive enzyme-linked immunoassay (ELISA) post-transplantation. In 90% of ELISA-positive patients, the presence of HLA antibodies was associated with persistent-recurrent acute rejections, compared with 34% in the ELISA-negative group (p < 0.005). There were 28 high-grade acute rejection episodes in the ELISA-positive group, compared with 36 in the ELISA-negative group (p < 0.0001). The ELISA-positive patients required a greater intensity of immunosuppressive therapy. The patients with ELISA-detected anti-HLA antibodies were at least 3-fold more likely to develop high-grade acute rejection and persistent-recurrent acute rejection, and 7-fold more likely to develop multiple episodes of persistent-recurrent acute rejection, compared with ELISA-negative patients. CONCLUSIONS: ELISA-based screening for the development of HLA antibodies is a reliable method that can identify lung transplant recipients at increased risk for high-grade and persistent-recurrent acute rejection. Although bronchiolitis obliterans appears as a point of no return in the evolution of lung-transplanted patients, early detection of risk factors for acute rejection could indirectly decrease the incidence of bronchiolitis obliterans. These lung-transplanted patients may benefit from an altered strategy of immunosuppression.

Experience with immune monitoring in lung transplant recipients: correlation of low immune function with infection.

BACKGROUND: Lung transplants, in particular, have the highest rate of infections among solid organ transplant recipients. However, there is no existing objective measure to predict the development of infections. We report the correlation between Cylex ImmuKnow (ng/mL ATP) values and various infectious syndromes in a large prospective cohort of lung transplant recipients. METHODS: We followed up 175 lung transplants that developed 129 infectious episodes. Multiple logistic regression analysis was performed; generalized estimating equations were used to determine the odds ratio for infections. RESULTS: The median ImmuKnow values in cytomegalovirus disease (49.3 ng/mL ATP), viral infection (70 ng/mL ATP), and bacterial pneumonia (92 ng/mL ATP) were significantly different from stable state (174.8 ng/mL ATP). The median ImmuKnow values of fungal disease (85 ng/mL ATP) and tracheobronchitis (123 ng/mL ATP) had a tendency to be lower than stable state (P=0.10), whereas patients with fungal colonization had comparable ImmunKnow values (167 vs. 174.8 ng/mL ATP). Of the patients colonized with fungus who subsequently developed fungal disease within 100 days, the median value of ImmuKnow was significantly lower than in those who did not develop fungal disease (22.5 vs. 183.5 ng/mL ATP; P<0.0001). Generalized estimating equation regression analysis showed ImmuKnow values less than or equal to 100 ng/mL ATP to be an independent predictor of infections (odds ratio 2.81). CONCLUSIONS: Cylex ImmuKnow assay monitoring has the potential to identify the patients at risk of developing infection and those colonized with fungus that are at risk of developing disease.

HLA-specific antibodies are risk factors for lymphocytic bronchiolitis and chronic lung allograft dysfunction.

Bronchiolitis obliterans syndrome (BOS) represents a major limitation in lung transplantation. While acute rejection is widely considered the most important risk factor for BOS, the impact of HLA-specific antibodies is less understood. Of 51 lung recipients who were prospectively tested during a 4.2 +/- 1.6-year period, 14 patients developed HLA-specific antibodies. A multi-factorial analysis was performed to correlate the prevalence of BOS with HLA antibodies, persistent-recurrent acute rejection (ACR-PR), lymphocytic bronchiolitis, and HLA-A, -B, and -DR mismatches. HLA-specific antibodies were associated with ACR-PR (10/14 vs. 11/37 with no antibodies, p < 0.05), lymphocytic bronchiolitis (8/14 vs. 10/37, p < 0.05), and BOS (10/14, vs. 9/37, p < 0.005). Other risk factors for BOS were: lymphocytic bronchiolitis (13/18 vs. 6/33 with no lymphocytic bronchiolitis, p < 0.0001), ACR-PR (12/21 vs. 7/30 with no ACR-PR, p < 0.05), and the number of HLA-DR mismatches (1.7 +/- 0.48 in BOS vs. 1.2 +/- 0.63 without BOS, p < 0.05). The presence of antibodies exhibited a cumulative effect on BOS when it was associated with either lymphocytic bronchiolitis or ACR-PR. The complex relationship between the development of HLA antibodies and acute and chronic lung allograft rejection determines the importance of post-transplant screening for HLA-specific antibodies as a prognostic element for lung allograft outcome.