Abstract: Our review included six RCTs (representing a total of 278 adult lung transplant recipients) that assessed the use of T-cell antibody induction. Evaluation of the included studies found all to be at high risk of bias. We conducted comparisons of polyclonal or monoclonal T-cell antibody induction versus no induction (3 studies, 140 participants); polyclonal T-cell antibody versus no induction (3 studies, 125 participants); interleukin-2 receptor antagonists (IL-2RA) versus no induction (1 study, 25 participants); polyclonal T-cell antibody versus muromonab-CD3 (1 study, 64 participants); and polyclonal T-cell antibody versus IL-2RA (3 studies, 100 participants). Overall we found no significant differences among interventions in terms of mortality, acute rejection, adverse effects, infection, pneumonia, cytomegalovirus infection, bronchiolitis obliterans syndrome, post-transplantation lymphoproliferative disease, or cancer. We found a significant outcome difference in one study that compared antithymocyte globulin versus muromonab-CD3 relating to adverse events (25/34 (74%) versus 12/30 (40%); RR 1.84, 95% CI 1.13 to 2.98). This suggested that antithymocyte globulin increased occurrence of adverse events. However, trial sequential analysis found that the required information size had not been reached, and the cumulative Z-curve did not cross the trial sequential alpha-spending monitoring boundaries. None of the studies reported quality of life or kidney injury. Trial sequential analyses indicated that none of the meta-analyses achieved required information sizes and the cumulative Z-curves did not cross the trial sequential alpha-spending monitoring boundaries, nor reached the area of futility. No clear benefits or harms associated with the use of T-cell antibody induction compared with no induction, or when different types of T-cell antibodies were compared were identified in this review. Few studies were identified that investigated use of antibodies against T-cells for induction after lung transplantation, and numbers of participants and outcomes were also limited. Assessment of the included studies found that all were at high risk of methodological bias. Further RCTs are needed to perform robust assessment of the benefits and harms of T-cell antibody induction for lung transplant recipients. Future studies should be designed and conducted according to methodologies to reduce risks of systematic error (bias) and random error (play of chance).

Plain-language summary: We analysed six studies that investigated the use of several different types of antibody therapies in 278 adult patients following lung transplantation. Flaws in study designs were found that indicated the studies were at risk of overestimating benefits and underestimating harms. Our analysis compared several types of antibodies, but with one exception - that antithymocyte globulin seemed to increase some adverse events - we found no significant differences in lung survival or rejection for any of the treatments. There was some uncertainty about this effect because the study was too small to be sure that observed benefits would apply to a larger population. We found no significant differences among therapies in terms of infection, bronchiolitis obliterans syndrome, post-transplantation lymphoproliferative disease, or cancer. Few investigated the use of T-cell antibodies after lung transplantation, and these included small numbers of participants. These limitations meant that our findings did not necessarily indicate no differences existed among comparisons in our analysis. To overcome this problem, larger and more robust randomised studies that assess the benefits and harms of antibodies against T-cells for people following lung transplantation are needed.