IMMUNE-RESPONSE TO INFECTION - ANTI-PHOSPHATIDYLCHOLINE ANTIBODIES INPATIENTS WITH BRUCELLOSIS

An indirect ELISA was adapted to measure individual classes of anti-ph osphatidylcholine (PC) antibodies in patients with brucellosis; a comp arison was made with patients with other infectious diseases and healt hy human controls. Immunoconjugates of alpha, gamma or mu chain specif icity were used. The results were compared with those of conventional tests for brucella antibodies, Rose Bengal, microagglutination (MAT) a nd Coombs tests, as well as with VDRL. The results indicated that alth ough all sera from patients with brucellosis were VDRL negative, 97% o f them (30 of 31) had higher levels of IgA or IgG anti-PC antibodies t han the healthy control group. The IgM anti-PC antibodies isotype was not discriminatory between both groups. Seven sera (19%) from patients with other infections had values of IgG anti-PC higher than those of the healthy group; three of them were VDRL positive. The mean ELISA va lues of IgG and IgA anti-PC (serum diluted 1 in 1600) in the brucellos is and healthy groups were: IgG, 0.80 SEM 0.17 versus 0.23 SEM 0.10; a nd IgA, 0.86 SEM 0.26 versus 0.35 SEM 0.15. The sensitivity and specif icity for the ELISA-PC were: IgG, 96.8% and 96.5%, respectively; IgA, 90.3% and 89.7%, respectively. Only one of 14 individuals clinically c ured from brucellosis had significant IgG anti-PC antibodies. In contr ast, all of these patients gave positive values in the conventional te st for brucellosis. No correlation was found between the serum levels of IgA, IgG anti-PC by ELISA-PC and the results of the MAT or Coombs t ests.