Many universities expect at least a grade C in English, maths and science (a grade C corresponds to a 4 or 5 for those familiar with the new grading structure used in the UK). However, depending on the course you wish to study, some will go further and ask for specific IGCSE subjects with certain grades.
Engineering
To study engineering for example, you will typically need A-levels or equivalent qualifications in chemistry or physics, and maths. You will therefore need to have good grades in science and maths IGCSEs.
Veterinary science
To qualify for veterinary schools, you are generally required to have at least five IGCSEs. These typically include maths, English language and science as a double or triple award. As courses are competitive at least a B (6 under the new grades) or higher should be achieved in all subjects.
Medicine and dentistry
To work in the medical professions at least seven IGCSEs are required at grades B(6) or above. This again must include the sciences, English language and maths.
Teaching
To go into teaching you are expected to achieve at least a grade C(4) in maths, English language and science. If you wish to teach a particular subject then, of course, a good mark in that subject would greatly help your application.