Hi Kajal,

PhD in immunology is offered by some institutes in India and you can apply for them either directly or through NET

However this field has tremendous scope abroad. You can explore Univeristies in Germany and Switzerland , they offer good scholarship oppprtunities and research prospects

I am attaching a link of Universities in Usa offering this programme

You can take up your GRE exams and prepare accordingly if you want to go abroad

https://m.university-list.net/rank/univ-100022.html

hope this helps!!!