Anti-16-kilodalton mycobacterial protein immunoglobulin m levels in healthy but purified protein derivative-reactive children decrease after chemoprophylaxis

Abstract

Serum responses against Mycobacterium tuberculosis HSP16 were determined for children with tuberculosis (TB) and for healthy purified protein derivative (PPD)-positive and PPD-negative children. Immunoglobulin G (IgG) and IgM responses were higher for TB patients than for other groups. After chemotherapy, IgM and IgG responses decreased for TB patients and PPD-positive subjects. Monitoring of anti-M. tuberculosis HSP16 responses could assist in the management of pediatric TB.

FIG. 1.

Frequencies of anti-HSP16 IgG or IgM responses before and after chemotherapy. Shown are percentages of sera with IgG and IgM responses to HSP16 for TB patients (n = 45) (A) and for healthy PPD⁺ (n = 60) (B) and PPD⁻ (n = 17) (C) subjects. Frequencies of positive sera were obtained by dividing the number of positive sera for each group by the total number of sera tested for that group. Hatched bars, results obtained with sera after 4 months of therapy.

FIG. 2.

Comparison of mean ODs of anti-HSP16 IgG before and after chemotherapy. (A and B) Mean ODs for anti-HSP16 IgG were analyzed before (A) and after (B) chemotherapy. For panel A, statistical comparisons were performed between data obtained with sera from TB patients and those from healthy PPD⁺ subjects (P < 0.05) and between data for healthy PPD⁺ versus PPD⁻ subjects (P < 0.05). For panel B, data from TB patients were compared with data from healthy PPD⁺ subjects (P < 0.05). (C and D) Mean ODs for anti-HSP16 IgM were analyzed before (C) and after (D) chemotherapy. For panel C, statistical comparisons were performed between data for TB patients versus healthy PPD⁺ subjects (P < 0.05) and between data for healthy PPD⁺ versus PPD⁻ subjects (P < 0.05). For panel D, data obtained from TB patients were compared with data for healthy PPD⁺ subjects (P < 0.05).