Perivascular deposits of IgM in the skin of transplant recipients during active cytomegalovirus infections. Correlation with IgM rheumatoid factors and IgM immune complexes

Detection of cytomegalovirus antigens in phagocytosed serum complexes from a patient with rheumatoid arthritis, vasculitis, peripheral neuropathy, cutaneous ulceration, and digital gangrene

A patient with rheumatoid arthritis, vasculitis, peripheral neuropathy, cutaneous ulceration, and digital gangrene was studied. Circulating immune complexes were detected by C1q binding although serum complement levels were within the normal range. Immunofluorescent staining of buffy coat cells with specific antisera showed the presence of IgG and IgM in phagocytosed inclusions but complement C3 was not detected. A monoclonal antibody specific for cytomegalovirus detected antigens in phagocytosed inclusions on one occasion. These results may suggest that cytomegalovirus antigens are a hitherto unidentified component of serum complexes in patients with rheumatoid arthritis and may contribute to the pathogenesis of the vasculitic complications of rheumatoid arthritis by participating in immune complex formation.

Presence and interpretation of vascular immune deposits in human skin: the value of direct immunofluorescence

Direct immunofluorescence investigation of the skin is an easy and valuable technique to establish the diagnosis immune complex vasculitis. Vascular immune deposits can be found in 60-80% of all cases. Absence of vascular immune deposits, however, does not exclude vasculitis per se, since the dynamics of the vasculitic process limit their presence in time. Knowledge of these dynamics is indispensable for both the clinician and the interpreter. Several practical options are discussed that may increase sensitivity. The specificity of vascular immune deposits has become a complex matter. Different immunoglobulin classes have different specificity, indicating that specificity also depends on the relative incidence of individual immunoglobulin classes. Some of these relative incidences seem to have changed over the years. Furthermore, several non-vasculitic diseases and conditions have now been described, that may show fluorescent pictures similar to vasculitis and thus decrease specificity.

Role of viral strains and host genes in determining levels of immune complexes in a model system: implications for HIV infection

Virus-antibody immune complexes form during infection with most RNA and DNA viruses, including those with human immunodeficiency virus (HIV). Yet a subset of individuals so infected apparently does not mount such responses. To understand the principles involved, we studied the formation and deposition of virus-antibody immune complexes in the circulation in a model system utilizing mice persistently infected with lymphocytic choriomeningitis virus (LCMV). Although mice of several genetic haplotypes could be persistently infected with LCMV, mount anti-LCMV antibody responses, and form immune complexes levels varied among murine strains. Earlier, genetic analysis of high and low immune complex formers, their F1 crosses, and appropriately selected recombinant inbred strains located the ability to mount heightened immune responses in genes within the MHC. Further, variations among LCMV strains in the capacity to incite high levels of immune complex formation were found. Persistent infection with LCMV Armstrong (ARM) strain was associated with high levels of complexes in the circulation and marked deposits in the glomeruli of high-responder SWR/J mice. In contrast, persistent infection of SWR/J mice with LCMV Traub strain led to very low levels of circulating complexes and minimal immune complex deposition in tissues. The amount of virus carried during both infections was roughly equivalent indicating that the genetics of both the host and the virus play essential roles in whether or not immune complexes develop. Antibody responses in SWR/J mice persistently infected with LCMV ARM were 5- to 10-fold higher than responses of age- and sex-matched mice infected with LCMV Traub.(ABSTRACT TRUNCATED AT 250 WORDS)