The Differential Agglutination Test as a Diagnostic Aid in Cases of Toxoplasmic Lymphadenitis

Abstract

We studied the AC/HS test in patients with TL to define its usefulness in diagnosing individuals presenting with LN and to determine its kinetics after the onset of LN. One hundred nine consecutive patients (158 serum samples) diagnosed serologically and by lymph node biopsy as having TL were studied. Specific patterns in the AC/HS test were noted to be dependent on the time from the clinical onset of LN (COLN). Acute AC/HS patterns were observed for more than 75% of patients who according to their histories had developed their TL within 6 months after COLN. Acute patterns were not observed beyond the 12th month except for a single patient for whom an acute pattern (400/800) persisted to the 13th month after COLN. Equivocal patterns were observed up to 36 months after COLN. Nonacute patterns were observed only for serum samples drawn at least 13 months after COLN. A nonacute pattern in an individual at less than 12 months after COLN should suggest an etiology other than TL. In such cases, investigation for alternative causes, including malignancy, should be instigated.

Kinetics and time dependence of the differential agglutination of acetone [AC]- and formalin [HS]-fixed Toxoplasma tachyzoites by serum of mice with experimental toxoplasmosis

“…2.5 ml of PBS containing 0.2 M 2-mercaptoethanol) then followed as twofold sera dilutions. The serum dilution for HS antigen (1:2,000) was assigned an antibody titer of 100 IU/ml (Dannemann et al 1990;Liesenfeld et al 2001;Montoya et al 2007). Sera that were negative in the conventional direct agglutination test were not evaluable in the AC/HS test.…”

“…Twofold dilutions of sera were done starting with 1:100. The serum dilution for AC antigen (1:100) was assigned an antibody titer of 50 IU/ml (Dannemann et al 1990;Liesenfeld et al 2001;Montoya et al 2007). Thus, an AC test titre of \50 IU/ml was considered in sera positive in conventional agglutination test and negative in the AC test.…”

“…The test was used to diagnose toxoplasmic encephalitis in AIDS patients (Suzuki et al 1988) and toxoplasmic lymphadentitis (Montoya et al 2007) and is one of a group of tests forming Toxoplasma serum profile (Kaul et al 2004) including a double sandwich IgM ELISA and the Sabin-Feldman dye test in combination with IgG avidity results to distinguish between recently acquired and distant infections in pregnant females (Liesenfeld et al 2001;Remington et al 2006). Results of the differential agglutination test are recorded as acute or non-acute patterns (Montoya et al 2007). The absence of knowledge about the accurate time of infection in humans did not allow for an estimate of the accurate time of conversion of the pattern in the AC/HS test from acute to non-acute (Montoya et al 2007).…”

“…The differential agglutination of acetone [AC]-fixed versus that of formalin [HS]-fixed tachyzoites is used in the differential agglutination (AC/HS test) a serological test that compares the titers obtained with Formalin-fixed tachyzoites (HS antigen) with those obtained with acetone-or methanol-fixed tachyzoites (AC antigen) (Montoya et al 2007). The test was used to diagnose toxoplasmic encephalitis in AIDS patients (Suzuki et al 1988) and toxoplasmic lymphadentitis (Montoya et al 2007) and is one of a group of tests forming Toxoplasma serum profile (Kaul et al 2004) including a double sandwich IgM ELISA and the Sabin-Feldman dye test in combination with IgG avidity results to distinguish between recently acquired and distant infections in pregnant females (Liesenfeld et al 2001;Remington et al 2006). Results of the differential agglutination test are recorded as acute or non-acute patterns (Montoya et al 2007).…”

“…Results of the differential agglutination test are recorded as acute or non-acute patterns (Montoya et al 2007). The absence of knowledge about the accurate time of infection in humans did not allow for an estimate of the accurate time of conversion of the pattern in the AC/HS test from acute to non-acute (Montoya et al 2007).…”