C8 beta subunit deficiency in a patient with recurrent neisserial infections

A 15-year-old woman with a history of recurrent episodes of meningococcal infections was admitted to our hospital with signs and symptoms indicating a meningeal inflammation. Since in the last few years some of the patients affected by recurrent meningococcal infections have been recognized to have selective complement deficiencies, the patient's serum was studied for determining the complement function. C8 was found to be present only in traces, with a pattern of partial identity as compared with that of the normal human serum. Moreover, total hemolytic complement was undetectable and could be completely restored with purified C8, but not with other complement components; thus, we concluded for the presence of a C8 deficiency state. Further reconstitution experiments carried out with sera having selective deficiencies of either C8 beta or C8 alpha-gamma subunits allowed us to recognize the presence of a dysfunctional C8 molecule lacking the beta chain, but possessing the alpha-gamma subunit. The clinical history of the patient, characterized by recurrent meningococcal infections, further supports the current concept of an increased susceptibility of the C8 beta-deficient patients to Neisseria meningitidis infections.