Effects of retroviral infections on immune function in African-American intravenous drug users.

OBJECTIVES

To determine the effect of retrovirus infection and co-infection, and intravenous substance use, on immune function in African-Americans.

DESIGN

A cohort of South Florida street-recruited African-American intravenous drug users formed the study population. The cohort consisted of 90 HIV-negative & human T-lymphotropic virus (HTLV)-negative, one HIV-negative & HTLV-I-positive, 11 HIV-negative & HTLV-II-positive, 79 HIV-positive & HTLV-negative, one HIV-positive & HTLV-I-positive and 21 HIV-positive & HTLV-II-positive individuals. The results reported are for the cross-sectional, baseline assessment of immune parameters.

METHODS

Lymphocyte phenotypic distributions and functional markers, including proliferative response to mitogens and natural killer cell cytotoxicity, were determined. Serum immunoglobulin (Ig) levels were determined as a measure of B-cell activity.

RESULTS

HTLV-II infection was associated with increases in CD8 lymphocyte count and serum Ig, but with no other significant immunologic changes. The distribution of CD4 and CD8 percentages, CD4:CD8 ratio, phytohemagglutinin (PHA) and pokeweed mitogen (PWM) reactivity, IgA and IgG for the four retrovirus serostatus groups suggested the possibility of interactive effects in the co-infected group, as demonstrated by a trend toward lower medians for CD4 and for PHA and PWM response and higher medians for IgG, IgA and CD8. Retrovirus-seronegative intravenous drug users had significantly impaired immune status compared with non-drug-using control individuals.

CONCLUSIONS

Immunologic dysfunction attributable to HTLV-II infection was minor compared with HIV infection in this population. Study subjects who were co-infected with HIV and HTLV demonstrated more impairment of immune function than individuals with single retrovirus infections.