CD4 and tropical spastic paraparesis: However, in the immunohistological studies of T-cell infiltration, predominantly CD3+CD4+ cells, was observed in the labial salivary glands of all examined HAM/TSP patients, suggesting that CD4+ T cells of HAM/TSP patients have transmigrating activity into the salivary glands even if its occurrence is not severe enough to induce the pathological changes that cause Sjögren syndrome, although the determination of these CD4+ T cells as HTLV-1-infected cells was not investigated.