Immunological aspects of immunodeficiency diseases part 100

The inability to generate sufficient CD3b results in increased susceptibility to pyogenic sepsis, especially infections caused by encapsulated bacteria. C3 deficiency may be due to complement utilization (eg in systemic lupus erythemathosus (SLE) or the presence of a C3 nephritic factor) or rarely autosomal recessive C3 deficiency. Factor I deficiency also leads to profound CD3 deficiency due to uncontrolled progression of  C3 cleavage. Hereditary C2 deficiency and less commonly inherited C4 deficiency may also be associated with the risk of pneumococcal sepsis.