In 1938, Margaret Pittman showed that the precipitin reaction around meningococcus colonies on immune serum agar plates was directly correlated with the mouse potency assay of each lot of antiserum.

In 1957, Dr. Pittman became the first female to lead a National Institutes of Health (NIH) laboratory. She was appointed chief of NIH Laboratory of Bacterial Products, a position she held until 1971.