V[D]J recombination explains:
1. the ability of the immune system to distinguish between self and non self
2. cooperativity between innate and adaptive immune responses
3. the genetic principle for generation of antibody diversity
4. hyperresponse of the immune system to allergens

Identify the correct statements regarding MHC I seen on the cells of vertebrate bodies:
I. They are found on the cell surface of all nucleated cells in the bodies of vertebrates, on platelets, but not on red blood cells.
II. The function of the class I MHC is to display intracellular proteins to cytotoxic T cells (CTLs).
III. Class I MHC itself can serve as an inhibitory ligand for natural killer cells (NKs).

1. Only I and II
2. Only I and III
3. Only II and III
4. I, II and III

Immune tolerance in pregnancy or maternal immune tolerance is the immune tolerance shown towards the fetus and placenta during pregnancy. Placenta plays an important role in this tolerance. All the following are functions of the placenta in this regard except:

1. There is presence of small lymphocytic suppressor cells in the fetus that inhibit maternal cytotoxic T cells
2. The placental trophoblast cells do not express the classical MHC class I isotypes
3. It secretes Neurokinin B containing phosphocholine molecules.
4. It does not allow any antibodies to cross over to the fetal side.