McIntyre was born in 1960 grew up in San Antonio, Texas, the only child of two school teachers. She received her PhD in physics in 1990 from the Massachusetts Institute of Technology in 1990. Her research focus is condensed matter physics, and she completed a dissertation "New models of magnetic interactions for bound magnetic polarons in dilute magnetic semiconductors" advised by Peter A. Wolff. When she was a graduate student, McIntyre co-founded the National Conference of Black Physics Students and organized the first NCBPS conference. For this work, she became one of the first recipients of the MIT's Dr. Martin Luther King Jr. Leadership Award in 1995. She continues to be involved in this organization.