CYTOKINE GENE-EXPRESSION IN THE FOOT PAD AND SPLEEN OF BALB CAJCL MICE INFECTED WITH MYCOBACTERIUM-LEPRAE/

The cytokine mRNAs expressed in the foot pads and spleens of BALB/cAJc l mice infected with Mycobacterium leprae were studied by the reverse transcriptase-polymerase chain reaction (RT-PCR) method using cytokine -specific primers for interleukin-l alpha (IL-1 alpha), -2, -4, -6, -1 0, -12-(p40), gamma interferon (IFN-gamma), tumor necrosis factor-alph a (TNF-alpha), and TNF-beta, and then for CD4 and CD8 markers. The pat tern of cytokine gene expression in the foot pad which supports M. lep rae growth was different from the expression in the spleen which does not permit M. leprae multiplication in mice. Before BALB/cAJcl mice we re infected with M. leprae, IL-1 alpha and TNF-beta mRNAs were express ed physiologically in the foot pad while all of the cytokine genes exa mined were expressed in the spleen. In the foot pads of mice inoculate d with M. leprae, in addition to the physiological appearance of IL-1 alpha and TNF-beta mRNAs, these signals were intensified. TNF-alpha ex pression was induced by the infection. On the other hand, in the splee ns of mice inoculated with M. leprae, CD4 mRNA expression disappeared on day 1 of the infection, which was accompanied by the reduced expres sion of 1L-2, -4, -6, and -12 mRNAs. The recovery of CD4 mRNA expressi on at a latter stage was accompanied by a corresponding increase of th e cytokine mRNA expression. It was suspected that these results might pel mit restricted growth of M. leprae in the foot pads of normal mice . Furthermore, our study suggests that tissue-specific, local, immunol ogic characteristics are important in M. leprae growth.