This lymphopenia is not due to apoptosis, but rather likely due to trafficking of cytotoxic lymphocytes to other tissues, whether part of this lymphopenia may contribute to angiogenesis in ischaemic tissue is unknown, but we do know that a subset of lymphocytes, CD31+ T cells, have pro-angiogenic functions (Hur et al. 2007; Kushner et al. 2010), and are mobilised by exercise (Ross et al. 2016, 2018a). This evidence concerns the gene PECAM1 and lymphopenia.