Interestingly, it has been found that as well as provoking a persistent or chronic rejection response, the indirect pathway may also sometimes induce “regulatory” T cells that are known to be responsible for transplant tolerance.

Researchers have also recently found evidence that regulatory B cells develop and can control an antibody response, but we do not understand precisely how regulatory T and B cells develop, and precisely how they suppress transplant rejection responses.

Eventually, it is anticipated that transplant patients may be treated with regulatory T and/or B cells generated specifically for their particular transplant, or with drugs that encourage their formation, and this will avoid the need for long-term immunosuppression.