Description

PA007392.m2b: Recombinant Anti-human CD32 Monoclonal Antibody (Clone: IV.3), Mouse IgG2b Kappa, In vivo Grade

Background

The recombinant IV.3 antibody binds to human CD32 (FcγRII or FCGR2), a cluster of differentiation molecule found on the surface of a variety of immune cells. CD32 is a surface receptor glycoprotein belonging to the Ig gene superfamily, has a low-affinity for the Fc region of IgG antibodies in monomeric form, but high affinity for IgG immune complexes. CD32 has two major functions: cellular response regulation, and the uptake of immune complexes. CD32 consists of Fc receptors FcγRIIa (CD32a), FcγRIIb (CD32b), and FcγRIIc (CD32c).

The most popular human Fc blocking reagents include:
Anti-human CD16 (clone 3G8), and CD32 (Clone IV.3): for flow cytometry, immunohistochemistry (IHC), and immunoprecipitation (IP). It is highly specific for FcγRII (CD32) and FcγRIII (CD16), and reduces background staining; it may not block all Fc receptors. Clones 10.1, and 22 or H22 are the most widely used anti-human FcγRI (CD64) clone for Fc blocking in flow cytometry and functional assays. It prevents non-specific Fc receptor binding on monocytes, macrophages, and dendritic cells, improving antibody specificity.
Purified human IgGs or mixes of human isotype controls: for general Fc blocking in IHC and immunofluorescence (IF). It is cheap and easy to use but it is less specific, and may even introduce unwanted immunoglobulins. Syd Labs supply various human IgG isotype controls.
Normal mouse serum, purified mouse IgG or isotype controls: for flow cytometry. It can serve as a control to block Fc receptors but it is non-specific for Fc receptors. It is cheap and easy to use but it is less specific, and may even introduce unwanted immunoglobulins. Our recombinant mouse IgG antibody mixes are affordable; the ratio of various IgGs is optimized and adjustable without any unwanted immunoglobulins.
Bovine Serum Albumin (BSA) or FBS: for general blocking in Western Blot (WB) and IHC. They are readily available to reduce non-specific binding but less effective at Fc receptor blocking.
Commercial Fc blocking solutions: for flow cytometry, IHC, and functional assays. They are normally pre-optimized and highly effective but more expensive than DIY solutions.

Best choice of human Fc blocking reagents based on your application are:
For flow cytometry: anti-human CD16 (Clone 3G8), CD32 (Clone IV.3), and CD64 (Clone 10.1, and 22 or H22).
For Immunohistochemistry (IHC) and Immunofluorescence (IF): Normal mouse serum, purified mouse or human IgGs or isotype controls or commercial Fc blocking kits. Our recombinant mouse IgG antibody mixes and recombinant human IgG isotype controls are affordable; the ratio of various IgGs is optimized and adjustable without any unwanted immunoglobulins.
For Western Blot and ELISA: BSA or FBS.
For functional assays (e.g., blocking Fc-mediated effects): Commercial Fc blocking reagents.

References of Anti-human CD32 Monoclonal Antibodies:

1、Platelet-neutrophil aggregate formation induces NLRP3 inflammasome activation in vaccine-induced thrombotic thrombocytopenia.
Martins-Gonçalves, R., et al. J Thromb Haemost. 2025 Mar;23(3):1034-1042. doi: 10.1016/j.jtha.2024.12.012. PMID: 39706368.
“Platelet-neutrophil aggregate formation was prevented through blockage of FcγRIIa with the neutralizing antibody IV.3 and through blockage of P-selectin or integrin αIIbβ3, also inhibiting caspase-1 activation. …Additionally, MCC950, an NLRP3 inflammasome inhibitor, blocked caspase-1 activation. …Taken together, these data show that VITT plasma induces platelet-neutrophil aggregate formation in a FcγRIIa-dependent manner and that platelet-neutrophil interactions may contribute to thromboinflammation in VITT patients by supporting NLRP3 inflammasome activation. …These data shed light on novel immunopathological events associated with inflammation and thrombosis in VITT patients. …Although rare, vaccine-induced thrombotic thrombocytopenia (VITT) following adenoviral vector COVID-19 vaccination is a concerning and often severe adverse effect of vaccination.”

2、Anchoring IgG-degrading enzymes to the surface of platelets selectively neutralizes antiplatelet antibodies.
Lynch, D. R., et al. Blood Adv. 2022 Aug 9;6(15):4645-4656. doi: 10.1182/bloodadvances.2022007195. PMID: 35737875.
“As a control, increasing concentrations of platelets treated with scIV.3-IdeS were incubated with equal volumes of autologous platelet-poor plasma for 1 hour at 37°C, and a western blot to detect human IgG was performed to measure IgG cleavage. …Concurrently with THP-1 cell preparation, platelets were stained with 5 μM of carboxyfluorescein succinimidyl-ester (CFSE) and then incubated with scIV.3 or scIV.3-IdeS and commercial antiplatelet antibodies (rabbit anti-CD41 and anti-CD42b antibodies; 250 ng) or ITP sera (1:25 dilution). …Because neutrophils, monocytes, and platelets express FcγRIIA, it was important to next determine the cellular distribution of scIV.3-FAM in these populations in blood. …The ability of scIV.3-IdeS to degrade surface-bound IgG is predicated on it being retained on the cell surface; however, previous work demonstrated engagement of FcγRIIA with divalent IV.3 caused receptor internalization. …To test whether the fusion of IV.3 to the N-terminus of IdeS affected its enzymatic activity, human IgG was incubated with increasing concentrations of either IdeS or scIV.3-IdeS. IdeS digests the heavy chains of IgG in a 2-step process, with the cleavage of the first heavy chain proceeding roughly 100-fold faster than that of the second.”

3、Anti-PF4 positivity and platelet activation after Ad26.COV2·S vaccination in Brazil.
Bokel, J., et al. Vaccine. 2024 Nov 14;42(25):126175. doi: 10.1016/j.vaccine.2024.126175. PMID: 39107160.
“In contrast, disruption of immunocomplexes with high concentration of heparin and blockage of FcγRII with the IV.3 antibody were capable of partially inhibiting the plasma induced platelet activation in samples of 2 anti-PF4 positive individuals, indicating activation in a FcγRIIa dependent manner. …Two were partially inhibited by high concentrations of heparin and blockage of FcγRII with IV.3 antibody. …Plasma obtained before vaccination produced similar results, suggesting a lack of association with vaccination. …Overall, from the 10 platelet activating plasmas, 6 individuals with elevated D-dimer and 2 individuals with anti-PF4 positivity were able to activate platelets regardless of FcγRIIa blockage, and disruption of immunocomplexes with high concentrations of heparin (100 U/mL). …Plasma samples of these 2 individuals taken prior to vaccination (week 0) had titers of anti-PF4 antibodies and were also capable of activating platelets in a FcγRIIa dependent manner.”

4、Antithrombotic efficacy and bleeding risks of vaccine-induced immune thrombotic thrombocytopenia treatments.
Leung, H. H. L., et al. Blood Adv. 2024 Nov 26;8(22):5744-5752. doi: 10.1182/bloodadvances.2024013883. PMID: 39293086.
“We have previously shown using a humanized VITT animal model that the anti-FcγIIa receptor monoclonal antibody, IV.3, the NETosis inhibitor GSK484 (a reversible peptidylarginine deiminase 4 inhibitor), and genetic ablation of peptidylarginine deiminase 4 in VITT mice led to a marked reduction in thrombosis. …We also compared the efficacy of these anticoagulants with IVIg using IV.3 as a control. …Effector deficient (aglycosylated) IV.3 was used for in vivo studies and was prepared as previously described. …Conversely, IVIg and IV.3, which interfere with FcγRIIa cell signaling via a nonspecific and specific blockade of FcγRIIa, respectively, protected platelets from clearance. These results suggest that thrombocytopenia in VITT is due to the clearance of platelets coated with VITT IgG immune complexes rather than peripheral consumption of activated platelets by extensive thrombosis. …The blockage of FcγRIIa with aglycosylated IV.3 provided the greatest reduction in thrombosis. Heparin was the least effective at reducing clots in VITT.”

5、Platelet-activating immune complexes identified in critically ill COVID-19 patients suspected of heparin-induced thrombocytopenia.
Nazy, I., et al. J Thromb Haemost. 2021 May;19(5):1342-1347. doi: 10.1111/jth.15283. PMID: 33639037.
“All samples were then tested for functional platelet activation in the serotonin release assay (SRA) with heparin (0, 0.1, 0.3, and 100 U/ml) as previously described. An anti‐human CD32 antibody (IV.3) was added to the SRA to confirm FcγRIIA engagement. …Anti‐human CD32 antibody (IV.3) was added to the SRA to confirm FcγRIIA involvement. …VWF antigen levels were assessed by the HemosIL von Willebrand Factor antigen automated chemiluminescent immunoassay (Instrumentation Laboratory). …All testing was done using plasma from blood collected in sodium citrate. Data represent mean ± standard error of the mean and are analyzed by Student’s t test. Results are considered significant at P < .05. ...Notably, six COVID‐19 patients demonstrated platelet activation by the SRA that was inhibited by FcγRIIA receptor blockade, confirming an immune complex (IC)‐mediated reaction. Platelet activation was independent of heparin but inhibited by both therapeutic and high dose heparin."

For more references about Anti-human CD32 Monoclonal Antibodies please contact our scientific support team with message@sydlabs.com.

Syd Labs provides the following in vivo grade recombinant anti-human CD16, CD32, and CD64 monoclonal antibodies:
Recombinant Anti-human CD16 monoclonal antibody (Clone: 3G8)
Recombinant Anti-human CD32 monoclonal antibody (Clone: IV.3)
Recombinant Anti-human CD64 monoclonal antibody (Clone: H22)

Syd Labs provides the following in vivo grade recombinant anti-mouse CD16, CD32, and CD64 monoclonal antibodies:
Recombinant Anti-mouse CD16/CD32 monoclonal antibody (Clone: 2.4G2)

Syd Labs provides the following recombinant anti-human CD16, CD32, and CD64 monoclonal antibodies for flow cytometry:
Recombinant Anti-human CD16 monoclonal antibody (Clone: 3G8) for flow cytometry
Recombinant Anti-human CD32 monoclonal antibody (Clone: IV.3) for flow cytometry
Recombinant Anti-human CD64 monoclonal antibody (Clone: H22) for flow cytometry

Anti-human CD32 Antibody (IV.3) from: Recombinant Anti-human CD32 Monoclonal Antibody, Mouse IgG2b Kappa (Clone: IV.3): PA007392.m2b Syd Labs