T4 cell


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T4 cell

(tē′fôr′)
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
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Our data also showed that neither cell morphology and MTT assay, nor the T4 cell counts were sufficient to predict correctly the fate of these exposures as it relates to the death endpoints for these cell lines.
Of the remaining 1,265 men with T4 cell counts above 200, only 68 developed the pneumonia during the study.
The results of the T4 cell analysis showed statistically significant differences (p < 0.05) between the MRC-5 and the A549 cell lines.
When the virus kills a T4 cell, the cell secretes something that kills other cells around it, his laboratory has found.
The expression of these keratins in T1R2 and T4R2 cells was in general lower than that in the parental T1 and T4 cells. The levels of keratins 7, 14, 17, and 18 did not change in these cell lines, whereas, because of the very low levels in A0 cells, the levels of keratin 6, a proliferation marker, were markedly increased (Figure 4B).
The T4 cells in turn stimulate antibody production by B lymphocytes.
The promising results were gleaned from only about 1,300 of the study's 3,200 subjects--those whose immune system was at least moderately impaired, as shown by a depressed level of T4 cells (special immune cells) -- 200 to 500 per cubic millimeter of blood.
"In terms of basic research on HIV," Sninsky continues, "the key areas facilitated by PCR are the identification of new messenger RNAs and rare messenger RNAs, the study of sequence variability over time (how the virus changes at different times in the same individuals, as well as between individuals), and the determination of the sequences that allow the virus to infect different types of cells--such as T4 cells in monocytes."
When the panel scientists looked at data collected on 1,300 participants who had fewer than 500 T4 cells upon entering the study, they found that people on zidovudine were about half as likely as those on placebo to develop symptoms of ARC or AIDS after one year in the study.
The new research indicates that AIDS patients harbor HIV in more than one of every 100 CD4-positive T4 cells -- the white blood cells that serve as the major target and reservoir of HIV.
The ability to kill infected cells is part of a larger process called cell-mediated immunity, in which virus- and foreign-material-eating macrophages, antibody-producing B cells and other immune cells are directed by T4 cells to do their various jobs.
The problem, they say in the DecemberCLINICAL IMMUNOLOGY AND IMMUNO-PATHOLOGY, could result from a similarity between the "hook" the virus uses to grab its target -- immune effector cells called CD4 or T4 cells -- and an unrelated protein on other white blood cell types that tells the immune system that these cells are "self" and shouldn't be rejected.