CD44 (IM7) Rat mAb (Alexa Fluor^® 555 Conjugate) #95235

Immunofluorescence (Frozen)

A. Solutions and Reagents

NOTE: Prepare solutions with reverse osmosis deionized (RODI) or equivalent grade water.

1. 20X Phosphate Buffered Saline (PBS): (9808) To prepare 1L 1X PBS: add 50 ml 20X PBS to 950 ml dH₂O, mix. Adjust pH to 8.0.
2. Formaldehyde: 16%, methanol free, Polysciences, Inc. (cat# 18814), use fresh and store opened vials at 4°C in dark, dilute in 1X PBS for use.
3. Blocking Buffer (1X PBS / 5% normal goat serum (#5425) / 0.3% Triton™ X-100): To prepare 10 ml: add 0.5 ml normal goat serum and 0.5 ml 20X PBS to 9.0 ml dH₂O, mix. While stirring, add 30 µl Triton™ X-100.
4. Antibody Dilution Buffer: (1X PBS / 1% BSA / 0.3% Triton™ X-100): To prepare 10 ml, add 30 µl Triton™ X-100 to 10 ml 1X PBS. Mix well then add 0.1 g BSA (#9998), mix.
5. Prolong^® Gold AntiFade Reagent (#9071), Prolong^® Gold AntiFade Reagent with DAPI (#8961).

B. Specimen Preparation - Frozen/Cryostat Sections (IF-F)

1. For fixed frozen tissue proceed with Immunostaining (Section C).
2. For fresh, unfixed frozen tissue, please fix immediately, as follows:

   1. Cover sections with 4% formaldehyde dilute in 1X PBS.

      NOTE: Formaldehyde is toxic, use only in fume hood.

   2. Allow sections to fix for 15 minutes at room temperature.
   3. Aspirate liquid, rinse three times in 1X PBS for 5 minutes each.
   4. Proceed with Immunostaining (Section C).

C. Immunostaining

NOTE: All subsequent incubations should be carried out at room temperature unless otherwise noted in a humid light-tight box or covered dish/plate to prevent drying and fluorochrome fading.

1. Block specimen in Blocking Buffer for 60 min.
2. While blocking, prepare primary antibody by diluting as indicated on protocol on product webpage in Antibody Dilution Buffer.
3. Aspirate blocking solution, apply diluted primary antibody.
4. Incubate overnight at 4°C.
5. Rinse three times in 1X PBS for 5 min each.
6. Coverslip slides with Prolong^® Gold Antifade Reagent (#9071) or Prolong^® Gold Antifade Reagent with DAPI (#8961).
7. For best results, allow mountant to cure overnight at room temperature. For long-term storage, store slides flat at 4°C protected from light.

Immunofluorescence (Immunocytochemistry)

A. Solutions and Reagents

NOTE: Prepare solutions with reverse osmosis deionized (RODI) or equivalent grade water.

1. 20X Phosphate Buffered Saline (PBS): (9808) To prepare 1L 1X PBS: add 50 ml 20X PBS to 950 ml dH₂O, mix. Adjust pH to 8.0.
2. Formaldehyde: 16%, methanol free, Polysciences, Inc. (cat# 18814), use fresh and store opened vials at 4°C in dark, dilute in 1X PBS for use.
3. Blocking Buffer (1X PBS / 5% normal goat serum (#5425) / 0.3% Triton™ X-100): To prepare 10 ml: add 0.5 ml normal goat serum and 0.5 ml 20X PBS to 9.0 ml dH₂O, mix. While stirring, add 30 µl Triton™ X-100.
4. Antibody Dilution Buffer: (1X PBS / 1% BSA / 0.3% Triton™ X-100): To prepare 10 ml, add 30 µl Triton™ X-100 to 10 ml 1X PBS. Mix well then add 0.1 g BSA (#9998), mix.
5. Prolong^® Gold AntiFade Reagent (#9071), Prolong^® Gold AntiFade Reagent with DAPI (#8961).

B. Specimen Preparation - Cultured Cell Lines (IF-IC)

NOTE: Cells should be grown, treated, fixed and stained directly in multi-well plates, chamber slides or on coverslips.

1. Aspirate liquid, then cover cells to a depth of 2–3 mm with 4% formaldehyde diluted in 1X PBS.

   NOTE: Formaldehyde is toxic, use only in a fume hood.

2. Allow cells to fix for 15 min at room temperature.
3. Aspirate fixative, rinse three times in 1X PBS for 5 min each.
4. Proceed with Immunostaining (Section C).

C. Immunostaining

NOTE: All subsequent incubations should be carried out at room temperature unless otherwise noted in a humid light-tight box or covered dish/plate to prevent drying and fluorochrome fading.

1. Block specimen in Blocking Buffer for 60 min.
2. While blocking, prepare primary antibody by diluting as indicated on product webpage in Antibody Dilution Buffer.
3. Aspirate blocking solution, apply diluted primary antibody.
4. Incubate overnight at 4°C.
5. Rinse three times in 1X PBS for 5 min each.
6. Coverslip slides with Prolong^® Gold Antifade Reagent (#9071) or Prolong^® Gold Antifade Reagent with DAPI (#8961).
7. For best results, allow mountant to cure overnight at room temperature. For long-term storage, store slides flat at 4°C protected from light.

Flow Cytometry, Methanol Permeabilization Protocol for Directly Conjugated Antibodies

A. Solutions and Reagents

All reagents required for this protocol may be efficiently purchased together in our Intracellular Flow Cytometry Kit (Methanol) #13593, or individually using the catalog numbers listed below.

NOTE: Prepare solutions with reverse osmosis deionized (RODI) or equivalent grade water.

1. 1X Phosphate Buffered Saline (PBS): To prepare 1 L 1X PBS: add 100 ml 10X PBS (#12528) to 900 ml water mix.
2. 4% Formaldehyde, Methanol-Free (#47746)
3. 100% Methanol (#13604): Chill before use
4. Antibody Dilution Buffer: Purchase ready-to-use Flow Cytometry Antibody Dilution Buffer (#13616), or prepare a 0.5% BSA PBS buffer by dissolving 0.5 g Bovine Serum Albumin (BSA) (#9998) in 100 ml 1X PBS. Store at 4°C.

NOTE: When including fluorescent cellular dyes in your experiment (including viability dyes, DNA dyes, etc.), please refer to the dye product page for the recommended protocol. Visit www.cellsignal.com for a full listing of cellular dyes validated for use in flow cytometry.

B. Fixation

NOTE: Adherent cells or tissue should be dissociated and in single-cell suspension prior to fixation.

NOTE: Optimal centrifugation conditions will vary depending upon cell type and reagent volume. Generally, 150-300g for 1-5 minutes will be sufficient to pellet the cells.

NOTE: If using whole blood, lyse red blood cells and wash by centrifugation prior to fixation.

NOTE: Antibodies targeting CD markers or other extracellular proteins may be added prior to fixation if the epitope is disrupted by formaldehyde and/or methanol. The antibodies will remain bound to the target of interest during the fixation and permeabilization process. However, note that some fluorophores (including PE and APC) are damaged by methanol and thus should not be added prior to permeabilization. Conduct a small-scale experiment if you are unsure.

1. Pellet cells by centrifugation and remove supernatant.
2. Resuspend cells in approximately 100 µl 4% formaldehyde per 1 million cells. Mix well to dissociate pellet and prevent cross-linking of individual cells.
3. Fix for 15 min at room temperature (20-25°C).
4. Wash by centrifugation with excess 1X PBS. Discard supernatant in appropriate waste container. Resuspend cells in 0.5-1 ml 1X PBS. Proceed to Permeabilization step.
   1. Alternatively, cells may be stored overnight at 4°C in 1X PBS.

C. Permeabilization

1. Permeabilize cells by adding ice-cold 100% methanol slowly to pre-chilled cells, while gently vortexing, to a final concentration of 90% methanol.
2. Permeabilize for a minimum of 10 min on ice.
3. Proceed with immunostaining (Section D) or store cells at -20°C in 90% methanol.

D. Immunostaining

NOTE: Count cells using a hemocytometer or alternative method.

1. Aliquot desired number of cells into tubes or wells. (Generally, 5x10⁵ to 1x10⁶ cells per assay.)
2. Wash cells by centrifugation in excess 1X PBS to remove methanol. Discard supernatant in appropriate waste container. Repeat if necessary.
3. Resuspend cells in 100 µl of diluted primary antibody, prepared in Antibody Dilution Buffer at a recommended dilution or as determined via titration.
4. Incubate for 1 hr at room temperature. Protect from light.
5. Wash by centrifugation in Antibody Dilution Buffer or 1X PBS. Discard supernatant. Repeat.
6. Resuspend cells in 200-500 µl of 1X PBS and analyze on flow cytometer.

流式细胞术，针对直接结合抗体的活细胞实验步骤

A. 溶液与试剂

注：使用反渗透去离子水 (RODI) 或同等级别的水配制溶液。

1. 1 X 磷酸盐缓冲生理盐水 (PBS)：要配制 1 L 1X PBS：将 100 ml 10X PBS (#12528) 添加到 900 ml 水，混合。
2. 抗体稀释缓冲液：购买即用型流式细胞术抗体稀释缓冲液 (#13616)，或在 100 ml 1x PBS 中溶解 0.5 g 牛血清白蛋白 (BSA) (#9998) 来配制 0.5 % BSA PBS 缓冲液。4°C 保存。

注：在您的实验中加入荧光细胞染料（包括活力指示染料、DNA 染料等）时，请参考染料产品网页，了解建议的实验步骤。访问 www.cellsignal.com，了解经验证用于流式细胞术的细胞染料完整列表。

B. 免疫染色

注：使用血细胞计数器或备选方法计数细胞。

注：如果使用全血，则需裂解红血细胞，并在免疫染色之前通过离心分离洗涤。

注：人 Fc 受体与兔 IgG 发生交叉反应。当感兴趣的细胞表达高水平的 Fc 受体蛋白（例如，巨噬细胞/单核细胞谱系）时，在用兔抗体进行免疫染色之前，用人 Fc 块预孵育活细胞。

注：最佳离心条件会根据细胞类型和试剂容量变动。一般，1-5 分钟 150-300g 将足以使细胞沉淀下来。

1. 将所需数目的细胞分装入试管或小孔中。（通常，每次测定 5 x 10⁵ 至 1 x 10⁶ 个细胞。）
2. 通过离心使细胞沉淀下来，移除上清液。
3. 在 100 µl 稀释的一抗中重悬细胞，这种一抗按建议的稀释度或如通过滴定所确定那样以抗体稀释缓冲液配制。
4. 在冰上孵育 30 分钟至 1 小时。避光。
5. 用抗体稀释缓冲液进行离心洗涤。弃去上清液。重复。
6. 在 200-500 μl 抗体稀释缓冲液中重悬细胞后用流式细胞分析仪进行分析。