In vitro studies have shown that
calcium channel blockers (CCB) inhibit
lectin-induced lymphocyte proliferation. However, no in vivo effects have been documented yet. In this study we evaluated the effects of CCB on in vivo cellular immunity by using
contact sensitivity to
oxazolone in mice. From 15 to 30 twelve-week-old female C3H mice were randomized into: 0.9 NS (
sham),
ethanol, CsA,
dexamethasone (DXM),
verapamil,
diltiazem, and
nifedipine groups. These study agents were given daily from day 1 to day 9 subcutaneously to the shaved abdominal wall. The mice were sensitized with
oxazolone to the abdominal wall on day 2 and challenged with
oxazolone on the right ear on day 8. Delayed-type
hypersensitivity was measured on day 10 and defined as the difference in thickness between the right (challenged) and left (control) ear of each mouse. The mean DTH of each study group was compared with that of the
sham, and the statistical significance was determined by a Student's t test. The percentage of change in DTH from the
sham was also calculated as: (mean DTH of study
drug group-mean DTH of
sham group)/mean DTH of
sham group x 100%. A negative value meant a suppressive effect on DTH; a positive value, an enhancing one. The CsA, DXM, and
nifedipine all had significant suppressive effects on DTH.
Verapamil had a significant enhancing effect.
Ethanol and
diltiazem had no significant effect. More studies employing other
antigens with several other cell-mediated response measurements along with DTH quantification should be done in order to determine the specificity of the immunosuppressive effect of CCB as well as the potential of any
calcium antagonist as an adjuvant suppressive agent.