Phenotype and cytokine expression of intralesional cells in borderline leprosy

We studied the cytokine profiles and cellular compositions in the lesions of borderline lepromatous (BL) and borderline tuberculoid (BT) leprosy patients in order to ascertain the immunological distinctions between these two groups. Using a modified, reliable, noninvasive, suction-induced blister technique to sample lesions, we determined that CD4+ T cells predominated in BT lesions; whereas CD8+ T cells predominated in BL lesions. However, the numbers of CD8+ per mm2 surface area of the lesion did not differ significantly between the two patient groups. In BT lesions, the elevation in the number of CD4+ cells was paralleled by the levels of soluble interleukin-2 (IL-2) receptor and soluble CD4 in the lesions. The CD4+:CD8+ ratio was 16:1 in BT lesions and 0.36:1 in BL lesions, although this ratio in the peripheral blood was similar in both groups. In addition, cells expressing the CD8 molecule dominated in the TCR-gamma delta subpopulation. The cytokine profiles in the lesions were not as distinctly different between BL and BT patients as were the cellular compositions. However, trends observed included elevated concentrations of IL-6 in BL lesions and elevated TNF-alpha levels in BT lesions.