ANTIBODY CLASSES AND SUBCLASSES IN CIRCULATING IMMUNE-COMPLEXES ISOLATED FROM MICE INFECTED WITH LACTIC-DEHYDROGENASE VIRUS

Abstract

Circulating immune complexes (CIC) were studied chronologically in lactic dehydrogenase virus (LDV)-infected mice. CIC containing IgM were isolated 3-9 days post-LDV infection and corresponded to an increase in serum IgM. IgG1-containing CIC were also transient in the serum of LDV-infected mice, being isolated only between days 5-13. The occurrence of IgG1 CIC did not correlate with an increase in total serum IgG1; it did correlate with a small (1:10) increase in IgG1 anti-LDV activity. CIC containing IgG2 were not isolated from LDV-infected serum until 15 days post-infection. This chronological appearance of IgG2 CIC did not correlate with the observed increase in total IgG2 concentration in LDV-infected mice on day 7; however, it was analogous to the rapid increase in free serum LDV-specific antibody. The nonspecific suppression of the immune response and tumor enhancement during the acute phase of LDV infection may be due to the immunoregulatory properties of IgG1 CIC.