Immune complexes and complement in serous and mucoid otitis media.

The occurrence and quantity of immune complexes in middle ear effusion (MEE) and serum, as well as serum levels of complement (C) factors were investigated in patients with chronic otitis media. Immune complexes were demonstrated in 85% of the serous MEE and in 28% of the sera. Depressed Clq values and presence of abnormal complexes, composed of subcomponents of the first C factor, indicated a disturbed function of the C system. Activation of C by the classical pathway was demonstrated in 23% of the patients. Decreased levels of properdin were also noted. The disorders within the C system tended to normalize as the otitis subsided.