Abstract: A diagnostic kit as well as a method for the examination of a human patient sample for the presence of neuromyelitis optica-specific antibodies are described, for which an initial substrate is incubated with human sample material, and said incubated initial substrate is examined using indirect immunofluorescence, whether neuromyelitis optica-specific antibodies have at least partially bound to said initial substrate. The solution described is characterized in that as said initial substrate, an aquaporin-4-containing native substrate is used as well as that said neuromyelitis optica-specific antibodies at least partially bound to said aquaporin-4-containing initial substrate are reacted with components of the complement system and the reaction of said complement system is detected by way of an indicator reaction.