Hypogammaglobulinaemia in nephrotic rats is attributable to hypercatabolism of IgG.

The effect of the nephrotic syndrome induced by puromycin aminonucleoside (PA) in rats on specific antibody responses to 2,4 dinitrophenyl (DNP) conjugated to either spider crab haemocyanin (MSH), a T cell-dependent antigen, or hydroxyethyl starch (HES), a T cell-independent type 2 antigen were studied. The serum IgG anti-DNP levels following immunization with both antigens were reduced in nephrotic animals compared with controls while IgM anti-DNP antibody titres were higher. The half-life of IgG anti-DNP antibodies passively transferred into non-immunized nephrotic rats was markedly reduced while the half-life of anti-DNP antibodies of the IgM class was comparable to that in controls. Low serum IgG and elevated IgM levels were seen in nephrotic animals compared to controls. Antibody-forming cells specific for DNP were demonstrated by immunohistology on rat spleens and the numbers of both IgG and IgM-producing cells were found to be significantly increased (P less than 0.05) in nephrotic animals in response to both DNP-HES and DNP-MSH. These data indicate that in nephrotic rats the alteration seen in the serum immunoglobulin levels is not attributable to reduced antibody production but increased catabolism of serum IgG antibodies.