Complex sentence: The research of Sainis has been focused on the field of immunobiology and his studies of T Cells and their receptors elucidated the "immune response to DNA" in mycobacterial antigens and lupus nephritis, an autoimmune disease.
Split into simpler sentences: The research of Sainis has been focused on the field of immunobiology. His studies covered how T Cells and their receptors influenced immune response to DNA in mycobacterial antigens and lupus nephritis, an autoimmune disease.