In 1969, he started collecting and aligning the amino acid sequences of human and mouse Bence Jones proteins and immunoglobulin light chains.

[1] While working under Michael Heidelberger at the Columbia University College of Physicians and Surgeons, Kabat studied the carbohydrate chemistry of embryonic-state-specific antigens and markers of white blood cells.

[3] During World War II, Kabat worked for the National Defense Research Committee on developing a meningitis vaccine, accurate syphilis test, and detectors for neutralizing the plant toxin ricin.

The bankruptcy of his family's dress manufacturing business during the Great Depression led to Kabat's life-long miserly attitudes toward personal and laboratory expenditures.

[3] As part of a post-doctoral fellowship funded by the Rockefeller Foundation, Kabat studied new methods of ultracentrifugation and electrophoresis alongside Arne Tiselius and Kai Pederson in Theodor Svedberg's Uppsala University lab in Sweden to research Immunoglobulin G (IgG).

[4] Following President Harry S. Truman's 1947 Executive Order 9835 mandating loyal screenings of all federal employees, Kabat was reported by Swedish biochemist James B. Sumner for supposedly being a Communist sympathizer.