A family with complement factor D deficiency.

A complement factor D deficiency was found in a young woman who had experienced a serious Neisseria meningitidis infection, in a deceased family member with a history of meningitis, and in three relatives without a history of serious infections. The patient and these three relatives showed a normal activity of the classical complement pathway, but a very low activity of the alternative complement pathway and a very low capacity to opsonize Escherichia coli and N. meningitidis (isolated from the patient) for phagocytosis by normal human neutrophils.

Acquired C1 inhibitor deficiency associated with systemic lupus erythematosus, secondary antiphospholipid syndrome and IgM monoclonal paraproteinaemia.

In this case report, a woman is described who developed systemic lupus erythematosus at the age of 36 years affecting the central nervous system and kidneys, showing the serological evidence of an acquired C1 inhibitor deficiency, but also developing an antiphospholipid syndrome and IgM lambda type paraproteinemia. During the 25 years follow-up she did not show any signs of angioedema. Although the immunological abnormalities are still constantly present, the disease has been quiescent since the past three years.

Acquired angio-oedema caused by IgA paraprotein.

The syndrome of acquired angio-oedema is characterized by late onset of recurrent bouts of angio-oedema or abdominal pain and may be caused by an acquired deficiency of C1-inhibitor (C1-INH), the inhibitor of the first component of complement. Acquired C1-INH deficiency has been described in approximately 50 patients and is strongly associated with malignant B-cell proliferations. We describe a patient with an 8-year history of recurrent abdominal symptoms and angio-oedema with acquired C1-INH deficiency, caused by the presence of IgA-kappa antibodies that inactivate C1-INH.

C5 deficiency in a patient with primary Sjögren's syndrome.

We report a case of C5 deficiency in combination with Sjögren's syndrome (SS). Our patient presented with polyarthritis and complaints of oral and ocular dryness. In the serum there was a very low titer of total hemolytic complement (CH50) due to a deficiency of the fifth complement component.

Deficiency of the beta subunit of the eighth component of complement presenting as arthritis and exanthem.

A 13-year-old boy presented with juvenile chronic arthritis of 6 months' duration. Antinuclear antibodies, anti-double-stranded DNA antibodies, and rheumatoid factor were not detected. Western blotting showed a deficiency of the beta subunit of the eighth component of complement.