T cells generally don't express Fc receptors so you can get away without using Fc block if you have a purified T cell population or are using a dump channel to exclude other Fc-expressing populations. B cells certainly do express Fc receptors so you'd certainly be best off blocking them. When staining mouse cells I usually use a commercial Fc block (anti-CD16/32) and when staining purified PBMCs I use 10% human serum.

When I use intracellular staining I always use buffers containing 5% FBS. Regardless of the method of preparation of cells (saponin method or methanol method). This is especially helpful in the analysis of activated cells.

T cells generally don't express Fc receptors so you can get away without using Fc block if you have a purified T cell population or are using a dump channel to exclude other Fc-expressing populations. B cells certainly do express Fc receptors so you'd certainly be best off blocking them. When staining mouse cells I usually use a commercial Fc block (anti-CD16/32) and when staining purified PBMCs I use 10% human serum.

yes, I usaully use Fc Block (anti-CD16/32) for all experiments with mouse B cells and 10% Heat inactivated (56C 30min) human serum for PBMC

Thanks for the answers.

Does the human serum need to be comercial or I can use heat inactivated serum from a healthy donor?

Healthy Donor is what I use

You Can use Fc Receptor Blocker (commercially available from Innovex or from BD) or alternatively, use your hand made PBA . .

If you are staining T cells from mouse, they are lovely cells that stain clean as long as you have some kind of general blocking agent (FCS or BSA) in your buffer. You don't really need Fc receptor blocking. However with B cells (or macrophages and other cells for that matter), you shall need to use Fc receptor blocking along with a mix of FCS/BSA/Rat serum. As someone mentioned, this is regardless of your method of permeabilization. You shall need to ensure that your blocking agents are present throughout all your Ab-Ag binding reactions, preferably on ice for maximum specificity.

Regardless of your surface or intra-cytoplasmic staining, because of the highly expression of Fc-gamma receptors by mouse B cells (and also monocytes or macrophages), you need to block them for a clean result and decrease background. Both commercial available Fc blockers or inactivated human AB serum are OK.

In the case of B cell analysis (as well as for monocytes/macrophages and dendritic cells), we always use buffers containing 5% FCS and block Fc receptors by preincubation with a commercial Fc-blocking antibody (anti-CD16/32).

I know it is rather late to respond - just found this thread when doing my own blocking. Should mention though that anti-CD16/32 blocks only FcGamma receptors (for IgGs), so if for any reason IgM is used, the sera are better.

For apoptotic pathway study of erythrocyte with Annexin V - FITC and 7 AAD , do we really need to use Fc block ?

Hey hey, just a quick question regarding the human serum. Does it need to be heat-inactivated? I isolate PBMCs from patients and use their respective serum as a blocking solution (for a FACS staining). Do you reckon there will be any problem with that? So far the staining seems to work out but maybe there is still something I haven't thought of...? Thanks in advance!

We use CD16/32 (FC block) to treat mouse spleen cells for FACS analysis prior to antibody staining. 

The very helpful answers from the scientists listed below:

Adeeb Rahman

T cells generally don't express Fc receptors

B cells certainly do express Fc receptors

When staining mouse cells I usually use a commercial Fc block (anti-CD16/32) and when staining purified PBMCs I use 10% human serum.

Kevin J Marchbank

Fc Block (anti-CD16/32) for all experiments with mouse B cells and 10% Heat inactivated (56C 30min) human serum for PBMC

Mukta Deobagkar

with B cells , you shall need to use Fc receptor blocking along with a mix of FCS/BSA/Rat serum. As someone mentioned, this is regardless of your method of permeabilization. You shall need to ensure that your blocking agents are present throughout all your Ab-Ag binding reactions, preferably on ice for maximum specificity.

Gabriella Di Felice

B cell analysis (as well as for monocytes/macrophages and dendritic cells), buffers containing 5% FCS and block Fc receptors by preincubation with a commercial Fc-blocking antibody (anti-CD16/32).

Jan Svoboda

Should mention though that anti-CD16/32 blocks only FcGamma receptors (for IgGs), so if for any reason IgM is used, the sera are better.

Hi everybody.

But what will you do if you have to block Fc receptors in human B cells to determine IgG surface expression? If you block with human serum it won´t work. So my question is, comercial human Fc block such as Human TruStain FcX™ (Fc Receptor Blocking Solution) from Biolegend does contain human Ig?

Thanks in advance

What about gamma globulin as Fc receptor blocker?

Hossein Asgarian-Omran only human AB serum? Why?

You use AB serum to avoid antibodies anti-A and -B blood type antigens.