IHC/Pathology Antibodies

PD-1: Programmed Death 1 (PD-1) is a member of the CD28/CTLA-4 family of T-cell regulators, expressed as a co-receptor on the surface of activated T-cells, B-cells, and macrophages. New studies have suggested that the PD-1/PD-L1 signaling pathway may be linked to anti-tumor immunity, as PD-L1 has been shown to induce apoptosis of activated T cells or inhibit activity of cytotoxic T cells. Unlike CD10 and BCL6, PD-1 is expressed by few B-cells, so anti-PD-1 may be a more specific and useful diagnostic marker in angioimmunoblastic lymphoma.

CTLA4: The CD152 antigen, also called CTLA4, is an integral membrane protein belonging to the immunoglobulin superfamily, which is expressed either as a 30 kDa monomer or as a disulfide-linked homodimer. It has homology with the T cell antigen CD28, and like CD28, is a ligand for CD80 and CD86. CTLA-4 is a receptor on T Helper cells that functions as an immune checkpoint and down-regulator of immune responses. Mutations in CTLA-4 are associated many autoimmune diseases.

Lp-PLA2: Lp-PLA2, also known as Lipoprotein-associated Phospholipase A2 or platelet-activating factor acetylhydrolase (PAF-AH), is an enzyme produced by inflammatory cells that functions to inactivate and degrade platelet-activating factor, a potent pro-inflammatory phospholipid, while also being responsible for hydrolyzing oxidatively modified polyunsaturated fatty acids. The products of the enzymatic actions of Lp-PLA2 have been linked to the development of atherosclerosis, and are positively correlated with increased risk of coronary heart disease and stroke.

Muc2: Mucin 2, also known as MUC2, is a human gene that encodes a member of the mucin protein family. The protein encoded by this gene forms an insoluble mucous barrier that protects the gut lumen. MUC2 expression is detected in human tissues such as normal colon, breast, prostate, and salivary gland, as well as in gastrointestinal, colonic, breast and prostate neoplasia.

Cytokeratin 18: Cytokeratin 18 (CK 18), a 45kDa protein, belongs to the acidic type of cytokeratins, and is typically expressed in simple, non-stratified epithelia. However, CK 18 is also expressed in basal and superficial cells of transitional epithelium, as well as in the luminal/secretory cells of complex epithelia. CK 18 antibody stains positively in Adenocarcinomas originating from simple and glandular epithelium, and also in poorly differentiated tumor cells of Squamous Carcinoma.

MLH1: MLH1, a mismatch repair protein involved in maintaining the integrity of genetic information, alongside MSH2, MSH6 and PMS2. This protein is commonly associated with hereditary non-polyposis colorectal cancer, as the MLH1 gene is frequently mutated in patients with this cancer. Studies have shown MLH1 to be deficient in a high percentage of patients with microsatellite instability, as well as endometrial and ovarian cancers. Use of Anti-MLH1 is optimized when paired in an IHC panel with MSH6, MSH2, and PMS2.