This is a multi-center, non-randomised, open-label, uncontrolled, single group study to investigate the safety and pharmacokinetics (PK) during 84 days repeat dosing treatment with 1000 micrograms (mcg) of inhaled GSK2269557 in addition to standard of care, in subjects with activated phosphoinositide 3-kinase (PI3K) delta syndrome /p110delta-activating mutation causing senescent T Cells, lymphadenopathy and immunodeficiency (APDS/PASLI). To date GSK2269557 has been administered to healthy subjects (smokers and non smokers), subjects with: stable Chronic Obstructive Pulmonary Disease (COPD); subjects experiencing a COPD exacerbation; and subjects with persistent, uncontrolled asthma. As this study is the first administration of GSK2269557 to subjects with APDS, this study will provide safety, tolerability, efficacy and pharmacokinetic data in this patient population. Up to 20 subjects will be enrolled into the study. The total duration of the study is approximately 30 weeks, including pre-screening/screening and follow-up.