Macintyre originally trained as an electrical engineer and worked as an apprentice electrician before enrolling to the University of Glasgow in 1878.

His proposers were John Gray McKendrick, James Thomson Bottomley, Magnus Maclean and William Jack.

On 5 February 1896 James Thomson Bottomley asked McIntyre to demonstrate an x-ray machine created by his uncle, William Thomson, Lord Kelvin following instructions from Rontgen (Lord Kelvin was ill and could not attend).

In the same year, he set up the world's first radiology department at the Glasgow Royal Infirmary, where X-ray photographs were used in the diagnosis and treatment of patients.

[4] He was also President of the West of Scotland Branch of the British Medical Association, Corresponding Fellow of the American and French Laryngological Associations, Fellow of the Royal Society of Edinburgh and of the Royal Microscopical Society, among other posts.