However, C3 levels were low normal, while only C4 levels were
depressed in another series of AFE patients from Japan.6 The Italian
group who previously found histology evidence for mast cell degranulation
looked for evidence of complement activation in their next
paper.36 Depressed amounts of C3a consistent with complement activation
was found in the pulmonary circulation of eight AFE patients
compared with six pregnant women dying of trauma. One of the complexities
in considering either mast cell degranulation or complement
activation as a possible mechanism of AFE is the fact that these
immune pathways are interrelated.41