Isoniazid prophylaxis differently modulates T-cell responses to RD1-epitopes in contacts recently exposed to Mycobacterium tuberculosis: a pilot study

Table 2 TST⁺ subjects without a past MTB exposure: trends of RD1 test during follow up in the responders*

Group of subjects analysed	Number of subjects N (%)	Time 1 0 months	Time 2 1–2 months	Time 3 6 months	Time 2 vs time 1	Time 3 vs time 1
		IFN-gamma (IU/ml)
No INH	6 (100)
PHA	6 (100)	9.9 ± 4.3	8.6 ± 4.1	12.1 ± 6.5	Ns	Ns
PPD	6 (100)	27.4 ± 3.1	21.4 ± 4.9	23.5 ± 3.8	Ns	Ns
QTF-G	6 (100)	21.1 ± 5.2	19.5 ± 7.2	20.2 ± 6.1	Ns	Ns
RD1 proteins	6 (100)	16.1 ± 4.5	16.3 ± 7.2	7.3 ± 2.2	Ns	Ns
RD1 peptides	6 (100)	7.5 ± 3.3	7.0 ± 4.7	5.7 ± 4	Ns	Ns
INH therapy	24 (100)
PHA	24 (100)	14.7 ± 2.7	16.8 ± 3	14.8 ± 2.8	Ns	Ns
PPD	24 (100)	17.6 ± 2.8	15.6 ± 2.7	14.1 ± 2.5	Ns	Ns
QTF-G	19 (79)	17.5 ± 2.7	11.6 ± 2.5	5.2 ± 1.3	p = 0.03	p = 0.0001
RD1 proteins	18 (75)	12.5 ± 2.6	5.4 ± 1.4	2.6 ± 0.9	p = 0.001	p = 0.0002
RD1 peptides	15 (63)	9.2 ± 1.7	3.4 ± 0.9	0.9 ± 0.1	p = 0.005	p = 0.0005

*Responders are defined as those responding to the tests at baseline.
T1: time 1 (baseline); T2. time 2 (after 1–2 months INH therapy), T3: time 3 (after 6 months, at therapy completion). IFN: interferon; PHA: Phytohemagglutinin; PPD: purified protein derivative; RD: region of difference; QTF-G: QuantiFERON TB Gold; IFN: interferon; IU: international units. INH: isoniazid; ns: not statistically significant.

ISSN: 1465-993X