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

Table 3 TST⁺ subjects with 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	5 (100)
PHA	5 (100)	14.2 ± 3.4	17.1 ± 4.5	17.5 ± 4.6	Ns	Ns
PPD	5 (100)	31.4 ± 2.5	33 ± 3.4	29.3 ± 4.5	Ns	Ns
QTF-G	5 (100)	16.4 ± 5.1	12.3 ± 4.4	16.3 ± 6.7	Ns	Ns
RD1 proteins	5 (100)	11.8 ± 3.8	8.9 ± 3.2	13.5 ± 6.1	Ns	Ns
RD1 peptides	5 (100)	6.1 ± 2	2.2 ± 0.5	4.6 ± 2	Ns	Ns
INH therapy	9 (100)
PHA	9 (100)	17.7 ± 6	20.4 ± 4.4	17.8 ± 4.1	Ns	Ns
PPD	9 (100)	19.6 ± 4.5	19.4 ± 4.7	24.2 ± 5.2	Ns	Ns
QTF-G	9 (100)	15.2 ± 4	11.3 ± 4	9.4 ± 2.7	Ns	Ns
RD1 proteins	9 (100)	6 ± 2	8.8 ± 3.3	11.9 ± 5.2	Ns	Ns
RD1 peptides	6 (66)	4.4 ± 2.7	4.1 ± 1.4	7 ± 3	Ns	Ns

*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