What type of cells are B cells and T cells?

Lymphcytes. When blood is examined under the microscope an array of cells are defined mostly RBC but also larger white cells known as polymorphoneuclear WBC's, marcrophages and a group of small round cells known as lymphocytes. Robt Good was able to subclassify them into T and B cells, the former providing the cytotoxic CD8 cells and B cells producing antibody to attack invaders.