Table II.

The toxicity and immunosuppressive effect of PHA in guinea pigs previously immunized with killed tubercle bacilli

Group	48 hour mortality rate of PHA	Frequency of positive PPD skin tests (intermediate strength)^*
Group	48 hour mortality rate of PHA	24 hours	48 hours
10 mg.^†	3/5	0/2	0/2
5 mg.^†	3/5	0/2	0/2
2.5 mg.^†	0/4	0/4	0/4
2.5 mg.^‡	0/7	0/7	0/7
Control animals		3/4	3/4

A positive skin test was defined induration of 5 mm. or greater At full strength PPD, 3 of the 15 PHA-treated animals had positive skin tests as did all 4 of the control animals.

^†

Unabsorbed.

^‡

Absorbed.