RELATIVE RESISTANCE TO HIV-1 INFECTION OF CD4 LYMPHOCYTES FROM PERSONS WHO REMAIN UNINFECTED DESPITE MULTIPLE HIGH-RISK SEXUAL EXPOSURES

Some individuals remain uninfected with human immunodeficiency virus t ype-1 (HIV-1) despite multiple high-risk sexual exposures. We studied a cohort of 25 subjects with histories of multiple high-risk sexual ex posures to HIV-1 and found that their CD8(+) lymphocytes had greater a nti-HIV-1 activity than did CD8(+) lymphocytes from nonexposed control s. further studies indicated that their purified CD4(+) lymphocytes we re less susceptible to infection with multiple primary isolates of HIV -1 than were CD4(+) lymphocytes from the nonexposed controls. This rel ative resistance to HIV-1 infection did not extend to T-cell line-adap ted strains, was restricted by the envelope glycoprotein, was not expl ained by the cell surface density of CD4 molecules, but was associated with the activity of the C-C chemokines RANTES, MIP-1 alpha, and MIP- 1 beta. This relative resistance of CD4(+) lymphocytes may contribute to protection from HIV-1 in multiply exposed persons.