Molecular cloning and expression of equine interleukin 2.

The researchers have successfully cloned and expressed equine Interleukin-2, a kind of protein involved in immune response. The cloned product, derived by comparing with human IL-2 sequences, enhances the proliferation of horse’s blood cells, demonstrating species-specific binding and thus failing to support mouse cell proliferation.

Molecular Cloning of Equine Interleukin 2

• The researchers focused on Interleukin 2 (IL-2), an important cytokine involved in the immune response of mammals. Particularly, they studied equine IL-2, originating from horses.
• Using a technique called Polymerase Chain Reaction (PCR), they successfully replicated the equine IL-2 cDNA (complementary DNA) in vitro or in a controlled lab environment.
• Primers used in the PCR process were based on the sequence of human IL-2, thus serving as a reference point for developing the equivalent section in equine IL-2.
• They inferred that the cloned product contained the entire coding sequence for equine IL-2, inferred based on its similarity to other known sequences.

Expression and Functionality of Cloned Equine IL-2

• The researchers then expressed the cloned equine IL-2 in COS cells, an established cell line used for scientific research.
• They observed an increase in the proliferative response of equine peripheral blood mononuclear cells when treated with the recombinant product. These cells are part of the immune system and their proliferation signifies an immune response.
• However, the researchers noted the cloned equine IL-2 failed to support the growth of murine CTLL-2 cells, a type of mouse lymphocyte. This indicated a species-specific response, signifying this version of IL-2 might not be universally functional across all mammals.

Species-Specific Substitutions

• The researchers also identified specific alterations in those sequences associated with p55 and p75 binding, a reference to characteristics of certain IL-2 receptor subtypes.
• These alterations appear to account for the species-specific functionality of the cloned equine IL-2, providing a plausible explanation for its inability to support murine CTLL-2 cell proliferation.