Non HLA Antibodies in Serum Prior to the Onset of Chronic Lung Allograft Dysfunction

Abstract

PurposeNon-human leukocyte antigen (HLA) antibodies have been associated with chronic lung allograft dysfunction (CLAD). Whether they predate CLAD is unclear. We hypothesized that patients destined to develop CLAD might develop non-HLA antibodies prior to CLAD onset.MethodsIn a single centre retrospective study, we examined 100 consecutive crossmatch negative recipients of a bilateral lung transplant between 1 January 2013 and 31 December 2014. Using a two-colour fluorescent antigen microarray with 152 unique antigens, we measured IgG and IgM autoantibodies in pre-transplant and six months post-transplant serum samples. Log2-transformed mean fluorescent intensities (MFIs) were determined for each antigen. CLAD was determined using published definitions. Significance analysis of microarrays (SAM) was used to analyze differences in antigen reactivity with a false discovery rate of 0.05. Paired and unpaired analyses were used to examine differences within and between recipients who developed CLAD within 5 years and recipients who remained CLAD free at 5 years post-transplant.ResultsSerum samples were available for 96 recipients - 35 (36.5%) developed CLAD and 61 remained CLAD-free within 5 years. Total IgM and IgG reactivity decreased in most patients post-transplant (Fig 1A), although IgM levels were stable in patients developing CLAD. Three IgM autoantibodies - including anti-club cell secretory protein (CCSP, Fig 1B) - increased in most patients post-transplant; this increase was of greater magnitude in patients later developing CLAD. Patients destined to develop CLAD also had an increase in IgG fluorescence directed at human core histones (Fig 1C).ConclusionOur results suggest that there may be important differences in non-HLA antibody reactivity that appear before the onset of CLAD. These observations, which require validation in further studies, may also indicate a specific role for non-HLA antibodies directed at club cell secretory protein and nuclear antigens in CLAD development. Non-human leukocyte antigen (HLA) antibodies have been associated with chronic lung allograft dysfunction (CLAD). Whether they predate CLAD is unclear. We hypothesized that patients destined to develop CLAD might develop non-HLA antibodies prior to CLAD onset. In a single centre retrospective study, we examined 100 consecutive crossmatch negative recipients of a bilateral lung transplant between 1 January 2013 and 31 December 2014. Using a two-colour fluorescent antigen microarray with 152 unique antigens, we measured IgG and IgM autoantibodies in pre-transplant and six months post-transplant serum samples. Log2-transformed mean fluorescent intensities (MFIs) were determined for each antigen. CLAD was determined using published definitions. Significance analysis of microarrays (SAM) was used to analyze differences in antigen reactivity with a false discovery rate of 0.05. Paired and unpaired analyses were used to examine differences within and between recipients who developed CLAD within 5 years and recipients who remained CLAD free at 5 years post-transplant. Serum samples were available for 96 recipients - 35 (36.5%) developed CLAD and 61 remained CLAD-free within 5 years. Total IgM and IgG reactivity decreased in most patients post-transplant (Fig 1A), although IgM levels were stable in patients developing CLAD. Three IgM autoantibodies - including anti-club cell secretory protein (CCSP, Fig 1B) - increased in most patients post-transplant; this increase was of greater magnitude in patients later developing CLAD. Patients destined to develop CLAD also had an increase in IgG fluorescence directed at human core histones (Fig 1C). Our results suggest that there may be important differences in non-HLA antibody reactivity that appear before the onset of CLAD. These observations, which require validation in further studies, may also indicate a specific role for non-HLA antibodies directed at club cell secretory protein and nuclear antigens in CLAD development.