What effect does interleukin-2 (released by T helper cells) have on cytotoxic T cells? Does it stimulate naive killer T cells to recognise antigens that are specific to their T cell receptors? Then these killer T cells are activated upon binding to specific antigen-MHC complexes of infected/cancerous cells, facilitated by CD8 receptors. They release perforin which punctures and lyses the infected cell.
Sounds right to me

! Although if you look through exam questions, information about CD4 or CD8 is not highly examinable (but it's kind of fun to know).
Do B lymphocytes also play a role in organ transplant rejection?
And also how are cytotoxic T cells destroy these transplanted cells, if they usually become activated by binding with MHC marker-antigen complexes on the surface of infected cells.
Wouldn't these transplanted cells only have MHC markers on their surface, not antigens (as they have not been infected with any pathogen themself) ?
Correct me if I'm wrong here:
If cytotoxic T cell is activated by the whole process of cell-mediated immunity, then B cell is activated as well, since when helper T cell is stimulated (as mention above by grannysmith), it releases interleukin-2, which plays a vital role in both humoral + cell mediated immunity, then yes, B cell will be activated. (You can see the example of Rhesus incompatibility)
All cells have MHC markers in the surface (except Red blood cells). MHC (major histocompatiblity complex) alone themselves are not markers, but are GENES that code for marker. Since these genes contain the genetic information of a person, everybody MHC is unique. Hence, when the body see the different coding genes on the transplant tissues, it will recognize them as non-self.
Antigen doesn't always mean non-self molecules, it helps you to differentiate between self and non-self molecules. Hence, in the body, we can have self antigen and non-self antigen, where self can be the glycoprotein producing from the person own cell surface or non-self as the membrane structures, viral protein coats or foreign particles.