Impaired humoral immunity following COVID-19 vaccination in HTLV-1 carriers.

BACKGROUND: Whether human T-lymphotropic virus type 1 (HTLV-1) carriers can develop sufficient humoral immunity after coronavirus disease 2019 (COVID-19) vaccination is unknown. METHODS: To investigate humoral immunity after COVID-19 vaccination in HTLV-1 carriers, a multicenter, prospective observational cohort study was conducted at five institutions in southwestern Japan, an endemic area for HTLV-1. HTLV-1 carriers and HTLV-1-negative controls were enrolled for this study from January to December 2022. During this period, the third dose of the COVID-19 vaccine was actively administered. HTLV-1 carriers were enrolled during outpatient visits, while HTLV-1-negative controls included health care workers and patients treated by participating institutions for diabetes, hypertension, or dyslipidemia. The main outcome was the effect of HTLV-1 infection on the plasma anti-COVID-19 spike IgG (IgG-S) titers after the third dose, assessed by multivariate linear regression with other clinical factors. RESULTS: We analyzed 181 cases (90 HTLV-1 carriers, 91 HTLV-1-negative controls) after receiving the third dose. HTLV-1 carriers were older (median age 67.0 vs. 45.0 years, p < 0.001) and more frequently had diabetes, hypertension, or dyslipidemia than did HTLV-1-negative controls (60.0% vs. 27.5%, p < 0.001). After the third dose, the IgG-S titers decreased over time in both carriers and controls. Multivariate linear regression in the entire cohort showed that time since the third dose, age, and HTLV-1 infection negatively influenced IgG-S titers. After adjusting for confounders such as age, or presence of diabetes, hypertension, or dyslipidemia between carriers and controls using the overlap weighting propensity score method, and performing weighted regression analysis in the entire cohort, both time since the third dose and HTLV-1 infection negatively influenced IgG-S titers. CONCLUSIONS: The humoral immunity after the third vaccination dose is impaired in HTLV-1 carriers; thus, customized vaccination schedules may be necessary for them.

Adult T-cell Leukemia/Lymphoma as a Methotrexate-associated Lymphoproliferative Disorder in a Patient with Rheumatoid Arthritis.

The patient was a 74-year-old Japanese woman with rheumatoid arthritis (RA) who developed generalized lymphadenopathy with elevated levels of lactase dehydrogenase (LD), and soluble IL-2 receptor (sIL-2R). She was found to be positive for anti-human T-cell leukemia virus type 1 (HTLV-1) antibodies. Her symptoms and laboratory abnormalities spontaneously regressed after the cessation of methotrexate (MTX), suggesting that she had an MTX-associated lymphoproliferative disorder; however, her lymphadenopathy appeared again approximately 14 months later with LD and sIL-2R elevation. A histopathological analysis and Southern blotting of a lymph node biopsy specimen for HTLV-1 provirus supported the diagnosis of adult T-cell leukemia/lymphoma (ATL) (lymphoma type). These data confirmed that an HTLV-1 positive RA patient may develop ATL.