I’ve always understood B cells are for extra cellular pathogens and T cells are for intracellular pathogens is this incorrect?
In the solutions my teacher made for a question asking how b and T cells work together an explanation is B cells are for extracellular environment whereas T cells are for intracellular environment.
CD8 T cells (cytotoxic T cells) can kill infected cells, so they do play an important role in the response against intracellular pathogens. However, B cells do as well as they can produce neutralizing antibodies that prevent the virus from being able to infect a cell. Think about vaccines, very few induce a T cell response but rather are aiming to produce neutralizing antibodies against the virus/bacteria.
Helper T cells are also very important in intracellular and extracellular pathogen responses. There are subtypes of Th cells that direct intracellular or extracellular responses (don't worry about this but I am just showing you how they have roles in both types of infections). For example, helper T cells are important for activating B cells to produce antibodies in extracellular (and intracellular) infections.
So overall, I see helper T cells and B cells as being involved in both types of infections. However, cytotoxic T cells are not very useful in extracellular pathogen response. I would discuss this further with your teacher to maybe understand what they meant by B cells = extracellular and T cells = intracellular.
It could have been an oversimplification (or maybe VCE knowledge-wise it is ok?- someone here may be able to comment on that I am not very up to date with the study design).
EDIT: As SmartWorker has pointed out what your teacher says seems to be consistent with VCE knowledge. I may have gone into a bit too much detail, so sorry & just ignore if it confuses you!
Also so Naive T cells exist? Or are they cytotoxic T cells? I always thought it was T cells which proliferate and differentiate into T memory cells and Cytotoxic T cells but now I’m not quite sure
Naive T cells are T cells that have never seen their antigen before and live in the lymph nodes/secondary lymph tissue. They can be CD8 or CD4 cells. When they are presented their antigen they will proliferate into effector T cells (either CD8 or CD4) or memory cells and be allowed to travel to the site of infection.