Cellular and humoral immunity to purified protein derivative (PPD) in PPD skin reactive and nonreactive patients with pulmonary tuberculosis: comparative analysis of antigen-specific lymphocyte proliferation and IgG antibodies.
OBJECTIVE
To evaluate in vitro reactivity against tuberculin purified protein derivative (PPD) in patients with active pulmonary tuberculosis scoring either positive or negative upon intradermal PPD application (PPD-DTH).


METHODS
Two groups of patients with pulmonary tuberculosis, 22 PPD+ and 22 PPD-, were studied. Peripheral blood mononuclear cells (PBMC) were assayed for in vitro proliferation to PPD antigen, phytohaemagglutin, concanavalin A, and pokeweed mitogens. In the proliferation assay PBMC were incubated in a medium supplemented with serum (20% concentration) from healthy donors, autologous serum, or allogenic serum. Anti-PPD IgG concentration in patients sera were analyzed by ELISA. CD3+ lymphocytes from 10 patients in each group were tested for the expression of surface activation markers (HLA-DR and CD25/IL-2 receptors) by flow cytometry.


RESULTS
PPD- patients showed clinically and radiologically more advanced forms of pulmonary tuberculosis as compared with PPD+ patients. PBMC from both groups of patients proliferated in response to PPD effectively, but significantly higher de novo DNA synthesis was observed in PPD+ patients (p<0.001). Proliferative activity was not affected by the type of the serum supplement (autologous or allogenic) in the culture medium. Mitogen stimulation elicited similar proliferative responses in both groups. Similar percentages of T-lymphocytes and T-lymphocytes expressing CD25 activation markers were observed in both groups of patients. There was a borderline difference in the percentage of CD3+HLA-DR+ lymphocytes between these two groups of patients (p=0.05). At 1:1000 serum dilution a significant difference (p=0.002) in anti-PPD IgG concentrations was found between PPD- and PPD+ patients.


CONCLUSIONS
Patients with active pulmonary tuberculosis with a more favorable clinical course have a more potent specific cell-mediated immunity to PPD (positive skin reactivity in vivo and significantly greater lymphocyte proliferative response in vitro) than patients with a clinically more severe form of the disease. The concentration of PPD specific IgG in the serum appears to be higher in patients with relatively more severe forms of the disease.
Boras
Zagorka
Z
University Hospital for Lung Diseases Jordanovac, Jordanovac 104, 10000 Zagreb, Croatia. jozo.boras@zg.hinet.hr
Juretić
Antonio
A
Rudolf
Marija
M
Uzarević
Branka
B
Trescec
Anda
A
D000328:Adult; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D000917:Antibody Formation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D016009:Chi-Square Distribution; D015331:Cohort Studies; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007111:Immunity, Cellular / Q000502:physiology; D007070:Immunoglobulin A / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013601:T-Lymphocytes / Q000276:immunology*; D014373:Tuberculin / Q000276:immunology*; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000276:immunology*
D000888:Antibodies, Anti-Idiotypic; D007070:Immunoglobulin A; D014373:Tuberculin