CD28 and CD40 glycoproteins are present on the surface of T-lymphocytes (T-cells). They act as binding sites for cell-signalling molecules and are needed to trigger T-cell cloning during an immune response. A monoclonal antibody (mAb), which could inhibit the CD40 signalling pathway, was made from hamsters by the hybridoma method. Outline the procedure, beginning with a hamster, for producing mAbs that are suitable for use in another mammal, for example a mouse.
The ability of the mAb made in (a) to stop rejection of transplanted hearts in mice was tested against a protein, P, that blocks the CD28 signalling pathway. Four groups of mice were handled as follows: • group A - no treatment • group B - treated only with protein P • group C - treated only with mAb • group D - treated with both mAb and protein P. Fig. 2.1 presents the percentage survival of the transplanted hearts in the four groups of mice over an 80-day period.
Using Fig. 2.1, describe how effective the four treatments are.
Suggest why the transplanted hearts in groups B and D survive for different lengths of time.
The transplanted hearts showed that those in group A had substantial damage to their coronary arteries, whereas in group D these blood vessels looked normal. Explain the importance of the coronary arteries of the heart.
State two uses of mAbs in humans, apart from preventing rejection of transplanted tissue.