18
Diagnosis
Table 5D. Complement Deficiencies and Associated
Infection and Diseases
Component Infection Other diseases
Classical pathway
C1q, C1r, and
C1s, C2, C4
Encapsulated bacteria Systemic lupus erythematosus (SLE),
vasculitis, rheumatoid arthritis (RA),
Sjogren's syndrome (SS), systemic
sclerosis (SSc) glomerulonephritis
Lectin pathway
Ficolins (M, L, H) Bacterial infections when
with other immunologic
abnormalities
Pneumonia, ulcerative colitis
MASPs Bacterial infections when
with other immunologic
abnormalities
Pneumonia, pulmonary fibrosis, and
ulcerative colitis
Alternate pathway
Properdin, Factor
B, Factor D
Meningococcus Atypical uremic syndrome (aHUS),
glomerulonephritis
Terminal pathway
C3 Severe bacterial,
respiratory tract
Glomerulonephritis, SLE, RA,
aHUS, age-related macular
degeneration (AMD)
C5, C6, C7, C8,
C9
Meningococcus, Neisseria
spp.
SLE, glomerulonephritis vasculitis,
antiphospholipid syndrome (APS),
myasthenia gravis, TMA
Regulatory proteins
Factor H Encapsulated bacteria Immune thrombocytopenic
purpura (ITP), aHUS,
glomerulonephritis, SLE, AMD
Factor I Encapsulated bacteria aHUS, glomerulonephritis,
scleroderma, RA, vasculitis
CD46 aHUS
CD59, CD55 Paroxysmal nocturnal
hemoglobinuria (PNH)
