If you place N. fowleri cells that were grown on a petri dish in a test tube containing small amounts of serum containing the anti-N. fowleri antibodies, the antibodies in the serum will bind specifically to the N. fowleri amoeba cell membrain as see in the illustration.

It should be noted that these specific anti-N. fowleri rabbit antibodies bind best to N. fowleri, and bind to a much less degree or not at all to other species of amoeba. These anti-N. fowleri rabbit antibodies are called the primary antibodies.

After the primary antibody binds to the N. fowleri cell membrane proteins the indirect immunofluorescence technique continues by adding to your test tube a secondary antibody. You can purchase this secondary antibody from a scientific supply company.  These secondary antibodies have been made in goats to specifically bind to any rabbit antibody. Also, this secondary antibody has been covalently bound to a fluorescent dye or marker called fluorescein (FITC), as seen in the illustration.

FITC will produce a green glowing light called fluorescence when it is exposed to the appropriate light source. The photograph herein of the green glowing cells is a real picture of dozens of N. fowleri cells fluorescing after they have been mixed with anti-N. fowleri rabbit antibodies, FITC bound goat secondary antibodies, and exposed to the appropriate light source. This picture has been taken with a fluorescent microscope which allows you to see fluorescent light. The entire process of mixing primary antibodies with FITC bound secondary antibodies is called indirect immunofluorescence.

Fluorescent Microscope Image of N. fowleri

The fluorescing N. fowleri cells seen in the fluorescent microscope picture are dead, this is why the trophozoite form of these cells have assumed a round shape.  Note, the white bar in this picture is 20μm; consequently, you can estimate that the trophozoites range in diameter from about 7μm to 15μm.  If you are wondering why you cannot see the individual antibodies in this picture, antibodies are only about 15nm in length.