Reacts with the "cytolytic T lymphocyte associated antigen" CTLA-4. CTLA-4 is transiently expressed on activated CD28+ T cells and binds to CD80 and CD86 present on antigen presenting cells (APC) with high avidity. This interaction appears to deliver a negative regulatory signal to the T cell. There are recent reports which indicate that CTLA-4 is also expressed on B cells when cultured with activated T cells suggesting a possible role of CTLA-4 in the regulation of B cell response.

REFERENCES
1. Lindsten, T., K. P. Lee, E. S. Harris, et al. 1993. Characterization of CTLA-4 structure and expression on human T cells. J. Immunol 151: 3489.
2. Kuiper, H. M., M. Brouwer, P. S. Linsley, et al. 1995. Activated T cells can induce high levels of CTLA-4 expression on B cells. J. Immunol. 155: 1776.
3. Morton, P. A., X-T. Fu, J. A. Stewart, et al. 1996. Differential effects of CTLA-4 substitutions on the binding of human CD80 (B7-1) and CD86 (B7-2). J. Immunol. 156: 1047.
4. Barclay, N. A., M. L. Birkeland, M. H. Brown, et al. 1993. The Leucocyte Antigen Facts Book. p. 290. Academic Press.

Cat. No.	Description	Clone	Isotype	Size
34581A	Purified anti-human CTLA-4	BNI3.1	Mouse IgG2a	0.1mg
34582X	Biotinylated anti-human CTLA-4	BNI3.1	Mouse IgG2a	100 tests

Available soon: No Azide/Low Endotoxin (NA/LE) format for functional studies, PE and Cy-Chrome™ conjugates

PharMingen also supplies a number of antibodies for studies in cell interaction, including:

• CD23
• CD27
• CD28
• CD30
• CD40
• CD40 Ligand
• CD80
• CD86
• OX40

CD ROM Vol 2 was produced by staff at the Purdue University Cytometry Laboratories and distributed free of charge as an educational service to the cytometry community. If you have any comments please direct them to Dr. J. Paul Robinson, Professor & Director, PUCL, Purdue University, West Lafayette, IN 47907. Phone:(317) 494-0757; FAX (317) 494-0517; Web http://www.cyto.purdue.edu EMAIL robinson@flowcyt.cyto.purdue.edu