Expression of some leukocyte antigens (including CD45) and its isoforms (CD
2, CD4, CD5, CD6, CD7, and CD8) was examined in the human periapical granul
ation tissue samples in the present study. The majority of the infiltrating
cells expressed heavy molecular-weight isoforms of the CD45 antigen. Expre
ssion of CD2, CD5, CD6, and CD7 antigens was also detected, implying signif
icant roles for these antigens in the immune reaction taking place in peria
pical lesions. This suggests that the immune response taking place at the p
eriapical region is predominantly cellular and the humoral responses to ant
igenic challenge are conducted mainly by regional lymph nodes.