A new methodological approach to estimation of IgA1 and IgA2 content in human serum using recombinant IgA1 protease from Neisseria meningitidis.

Objectives: A new approach to estimation of IgA subclass levels and IgA1/IgA2 ratio using enzymatically active and inactive forms of Neisseria meningitidis IgA1 protease was developed.

Results: The approach was tested using the sera of healthy volunteers and patients with meningococcal meningitis. There was a significant increase in the IgA1 level in patients with meningitis (mean titer 1:1546 ± 352) compared to healthy volunteers (mean titer 1:546 ± 282), while the IgA2 content remained unchanged.