Sustained CD4 T Cell Response After Virologic Failure of Protease Inhibitor-based Regimens in Patients with HIV Infection
[SG Deeks, et al. JID 02000;181:946]

This is a report from San Francisco General Hospital of patients with over 16 weeks of PI-based therapy initiated before March 1997 (to permit at least 96 weeks of observation). There were 380 participants who were categorized by virologic response as having a complete response (viral load <400 copies/mL), a partial response, transient response, or no response. The analysis, as summarized below, showed that the CD4 cell response was directly related to the degree of viral suppression, but even patients who had virologic failure showed sustained CD4 cell responses.

Virologic and CD4 Response

	Virologic response at 96 weeks
	Complete n=171	Partial 74	Transient 86 (Rif)	No response 49 (Rif)
Median Baseline CD4 (/mm3)	206	114	103	109
Median Baseline VL (log10)	4.4	4.4	4.6	4.3
Median CD4 increase
48 wks	129	130	94	36
96 wks	190	151	87	*

Comment: This is an important study for showing that CD4 cell responses correlate with viral suppression, but it also showed that many patients who represent virologic failures have persistent increases in CD4 cell counts relative to baseline. This is referred to as "discordant" or "paradoxical" CD4 cell responses. It is not clear if this is due to partial viral suppression or an alternative mechanism, but data presented by S. Deeks at the 7th Retroviral meeting suggest that "fitness" may explain some of these discordant results [7th CROI Abstract LB10]. JGB, 5/3/2000