Which of the following features is not shared between ‘T cells’ and B cells’?
This appeared to be a tough question but let us analyze all the options step wise.

Both B cells and T cells have antigen specific receptors. T cells have an antigen specific T cell receptor (TCR) composed of a and b polypeptide chains in 95% cases to bind with the antigen. B cells have a B cell receptor (BCR) having unique antigen specificity composed of IgM and IgD on their surface to bind with the antigen.
Since MHC I is expressed on all the nucleated cells, so, it is likely to be present on both ‘B’ as well as ‘T’ cells. As discussed in our accompanying DVD on Immunology, the T cells undergo both negative and positive selection. Both these are described below:
Positive selection: T cells in the thymic cortex are allowed to survive only if their T cell receptor has affinity for the MHC molecule. If the T cells do not have any affinity for the MHC molecule, they are programmed to die. This is important because only if this affinity is present, the T cells can interact with the antigen presenting cells. So, positive selection is required for self MHC restriction.
Negative selection: T cells come in the thymic medulla after being already positively selected in the thymic cortex. In the medulla, if a T cell has affinity for ‘self antigens’, they are eliminated. This is called as negative selection. It is therefore required for the self tolerance.
Similar to the negative selection of the T cells, the B cells may also recognize ‘self antigens’ in the bone marrow. In this situation, the B cell undergoes antigen receptor gene rearrangement so as to express new antigen receptors. These new receptors are designed as to not recognize ‘self antigens’. This process is described as ‘receptor editing’. If because of any reason receptor editing does not take place, the B cells undergo apoptosis. This is the negative selection of B cells in the bone marrow.
Antigen Specific Receptors
Class I MHC Expression
Positive selection during development
All of the above