To certain infections: 26 (n = 22) of Finnish patients with recurrent respiratory infections vs.14 (n = 10) of healthy controls (p = 0.048) had C4A deficiency. Not unexpectedly, 50 of the patients with C4A deficiency had MBL concentrations .1.5 mg/ml, the mean human MBL serum concentration but notably, more than one-third had very high MBL levels (.4 mg/ ml). Further clinical studies are requir