CHARACTERISTICS OF A NON-COMPLEMENT-DEPENDENT C3-REACTIVE COMPLEX FORMED FROM FACTORS IN NEPHRITIC AND NORMAL SERUM

Abstract

When serum from a patient with membrano-proliferative glomerulonephritis and normal serum are mixed at 37°C, C3 is rapidly broken down to two more rapidly migrating components. In the mixture, a heat-labile pseudoglobulin, designated as the C3 nephritic factor or C3NeF, reacts with a pseudogolbulin in the normal serum, designated as cofactor, to form a C3 inactivator. By analogy with the cobra venom factor, the C3 inactivator is most likely a complex of the nephritic factor and cofactor. The complex has been designated as the C3 lytic nephritic factor or C3LyNeF. The reaction which results in the Formation of C3LyNeF requires the presence of Mg⁺⁺, is highly temperature sensitive but occurs very rapidly at 37°C. In 20 min at 37°C, C3LyNeF can break down over 80% of the C3 in a mixture of normal and nephritic serum.