TABLE 4.

Effect of temperature on M. tuberculosis uptake by human macrophages

Strain	Time of exposure (h)a	Uptake (% of initial inoculum) of M. tuberculosis at:
		23°C	30°C	37°C
H37Rv	2	6.1 ± 2	10 ± 3	16.8 ± 4b
	4	7.2 ± 4	12 ± 3	18 ± 5b
Erdman	2	7.4 ± 0.4	11.9 ± 4	19.7 ± 5b
	4	7.9 ± 3	14 ± 3	24 ± 6b

^aBacteria were exposed to different temperatures for 2 or 4 h, washed at 4°C, and used to infect macrophages in the presence of 10% heat-inactivated autologous serum. Results are means ± standard deviations.

^bP < 0.05 compared with uptake of bacteria exposed to 23 or 30°C.