The prozone effect exerted by the complement-binding anti-Le(a) on anti-D

BACKGROUND: Prozone phenomenon is seen with very high-titer antibodies in an immune serum. AIM: The prozone effect on anti-D by a low-titer anti-Le(a) was investigated associated with neonatal jaundice. MATERIALS AND METHODS: Standard methods were used in investigations. RESULTS: The child was born at full-term developed mild jaundice. With weak direct antiglobulin test+, her indirect serum bilirubin was progressed to 27.5 mg/dL in 48 h. Anti-D and anti-Le(a) were detected in the mother. Both these antibodies were detected in the child's serum though the eluate from red blood cells (RBCs) contained only anti-D. Mother's anti-D was masked by anti-Le(a) if the RBCs possessed both the antigens together. Anti-D was revealed only with D-positive RBCs lacking Le(a) or if the serum was modified by mixing with Le(a+) saliva or was heated at 56°C or fortified with citrate solution. CONCLUSION: An anti-D showed prozone effect exerted by the complement-fixing anti-Le(a) in the test.