WEBVTT

1
00:00:00.540 --> 00:00:03.160
<v ->The CD4 count, or the CD4 cell,</v>

2
00:00:03.160 --> 00:00:05.770
is the cell that HIV infects.

3
00:00:05.770 --> 00:00:07.420
Unfortunately, it also happens to be the cell

4
00:00:07.420 --> 00:00:10.943
which is responsible for controlling the HIV infection.

5
00:00:12.040 --> 00:00:14.970
So the paradox is that when HIV infects those CD4 cells,

6
00:00:14.970 --> 00:00:17.280
it actually facilitates its own propagation

7
00:00:17.280 --> 00:00:19.933
or it makes the control of its infection worse.

8
00:00:20.870 --> 00:00:23.270
And unfortunately, the CD4 cell, again, it controls

9
00:00:23.270 --> 00:00:25.580
not just the immune response to HIV.

10
00:00:25.580 --> 00:00:28.890
It controls the immune response to all sorts of things.

11
00:00:28.890 --> 00:00:32.060
So we're very interested in HIV medicine about the status

12
00:00:32.060 --> 00:00:35.130
of the CD4 health, or the number of CD4 cells.

13
00:00:35.130 --> 00:00:36.583
We call that a CD4 count.

14
00:00:37.420 --> 00:00:39.790
A normal CD4 count has a lot of variability

15
00:00:39.790 --> 00:00:41.910
and a lot of range but minimally 350.

16
00:00:41.910 --> 00:00:43.493
It could be as high as 1,500.

17
00:00:45.120 --> 00:00:48.610
And when CD4 counts are below 350, we currently recommend

18
00:00:48.610 --> 00:00:50.450
that people initiate therapies for HIV.

19
00:00:50.450 --> 00:00:52.840
That's why that number becomes so important.

20
00:00:52.840 --> 00:00:55.320
Another number in terms of CD4 cells that's important

21
00:00:55.320 --> 00:00:58.860
is 200 because 200 is the level at which we define

22
00:00:58.860 --> 00:01:01.590
someone as having AIDS or the level at which they are

23
00:01:01.590 --> 00:01:03.790
prone to having a lot of devastating

24
00:01:03.790 --> 00:01:06.580
and stereotypical HIV complications,

25
00:01:06.580 --> 00:01:09.343
again, the ones that we define as AIDS.