Context: The human T-lymphotropic viruses types 1 and 2 (HTLV-1 and HTLV-2) are highly prevalent among injection drug users in the United States. However, the clinical course of infection has not been well characterized.
Objective: To understand HTLV-1-and HTLV-2-associated laboratory abnormalities, which may provide insights into their underlying pathophysiology.
Design: Cohort study.
Setting: Five US blood centers.
Participants: A total of 133 HTLV-1-and 332 HTLV-2-seropositive former blood donors and 717 HTLV-seronegative donors followed up prospectively since 1991.
Main outcome measures: Selected serum chemistry tests and complete blood cell counts were analyzed at enrollment and approximately 2 years later in participants. Repeated-measures analyses were conducted to evaluate the effect of HTLV infection on laboratory measures.
Results: Compared with seronegative subjects, HTLV-1-seropositive subjects had 13% higher creatine kinase (P =.02) and slightly elevated lactate dehydrogenase (P =.03) levels at follow-up. The HTLV-2-seropositive participants had 11% higher absolute lymphocyte counts than seronegative subjects (P =.0001). Infection with HTLV-2 also appeared to be associated with slightly higher hemoglobin levels (P =.03) and hematocrit (P =.03) and with lower albumin levels (P =.01).
Conclusions: These results further our understanding of the biological mechanisms underlying HTLV and suggest that HTLV-associated laboratory changes are unlikely to alter clinical evaluation or counseling of otherwise healthy HTLV-infected subjects.