TOXOPLASMA INFECTION AND SYSTEMIC LUPUS-ERYTHEMATOSUS - ANALYSIS OF THE SEROLOGICAL RESPONSE BY IMMUNOBLOTTING

Aims-To examine the serological response of patients with systemic lup us erythematosus (SLE) and toxoplasma infection and to compare the blo t profiles with those from immunocompetent subjects of similar immune response. Methods-Forty serum samples from patients with SLE were test ed for toxoplasma antibodies using the dye and indirect haemagglutinat ion tests. Specific IgM was measured by mu-capture enzyme linked immun osorbent assay (ELISA). The sera were immunoblotted using antigen stri ps prepared from the RH strain of Toxoplasma gondii. For comparison, c ontrol blots were prepared from pooled sera from immunocompetent subje cts with serological evidence of acute (pool 1), or chronic (pool 2) t oxoplasma infection, or with no evidence of infection (pool 3). Result s-Some of the blot profiles from the patients with SLE were compatible with the corresponding serology but others showed considerable variat ion, particularly among the IgM blots. The blots from sera with low dy e test titres suggested that the latter could be false positive result s. Conclusions-Toxoplasma infection may enhance the production of auto antibodies which, when combined with the high titres characteristic of SLE, might interfere in the dye test and other serological tests. Imm unoblotting could prove useful in the immunocompromised for confirming the presence of specific toxoplasma antibodies and for the staging of infection in those with positive serology.