Prevalence of HTLV-I infection and immunosuppression in patients with oral malignant tumors

Adult T-cell leukemia (ATL) patients are frequently associates with other malignancies. To elucidate the possible association of HTLV-I infection with the tumorigenesis of oral malignancies in Kagoshima prefecture, I analyzed the correlation between HTLV-I and the patients with oral malignant tumor (OMT). The following results were obtained;1) The organ distribution of oral malignancies in Kagoshima prefecture was found in the tongue most frequently. The male to female sex ratio was 2 to 1 and the age distribution of the highest incidence ranged from 60 to 80 years. The most frequently observed histopathology was the squamous cell carcinoma (74/78 cases).2) HTLV-I seropositivity of OMT in total, was 2. 3 times more than that of normal adults in Kagoshima prefecture and the male to female sex ratio was 4 to 3.3) HTLV-I provirus was detected in 5 cases of 7 peripheral blood lymphocytes (PBLs) donors of the seropositive OMT.4) OMT was associated with HLA-DRw8 in significantly high frequency (cp seronegative OMT > seropositive OMT. The autologous proliferative response (APR)21 of PBLs was detected in 9 cases of 14 seropositive OMT, indicating immunological abnormality associated with HTLV-I infected OMT.6) When T-cell subset in the seropositive OMT were analyzed after the culture of PBLs, CD4/8 ratio was segregated to 2 groups, one with an increased CD4/8 ratio (3 cases) and the other with a decreased CD4/8 ratio (7 cases). The former produced poor prognosis and the latter a good prognosis.In conclusion, OMT infected with HTLV-I had a tendency of less immune response to HTLV-I and PHA compared with those of seronegative controls. The CD4/8 ratio was primarily associated with the prognosis of OMT. OMT had HLA-DRw8 in significantly high frequency comparing with the normal population. Thus, HLA-DRw8 and HTLV-I infection may interact each other and modulate the host immune system against OMT.