1044 IMPAIRED CHEMOTAXIS ASSOCIATED WITH DECREASED SERUM FACTOR B & INFECTION IN IDIOPATHIC NEPHROTIC SYNDROME OF CHILDHOOD (INSC)

The increased incidence of severe systemic infections in INSC secondary to bacteria with polysaccharide capsules suggests a defect in serum complement activity relating to chemotactic activity. Chemotactic function was assessed in INSC during 1) “severe” relapse, 2) “mild” relapse, & 3) “remission” with respect to A) chemotactic activity generated by INSC sera (±zymosan activation) B)chemotactic responses of INSC PMNs to control sera, & C)inhibitory effects of INSC sera and/or plasma on control PMNs (modified Bovden method). Serum chemotactic activity in 14 “severe” relapsing INSC patients was diminished compared to controls (p < 0.01) and 21 “mild” and “remission” patients (p<0.001). Chemotactic activity of zymosan activated sera was diminished compared to controls and to “mild” or “remission” states (p<0.025). Decreased serum chemotactic activity was related to occurrence of systemic bacterial infection, and decreased serum Factor B and albumin values. Serial determinations in “severe” cases demonstrated increasing chemotactic activity, serum Factor B & albumin associated with a positive response to treatment and return to clinical remission. Normal chemotactic responses of patient PMNs to control sera (±zymosan) were shown in all patient groups, and patient sera did not inhibit chemotactic function of control PMNs. These findings suggest that bacterial infection in INSC may be causally related to impaired serum chemotactic activity related to an abnormality of properdin pathway complement activation.