KIR2DL2 Antibody

What is KIR2DL2 and what is its role in the immune system?

KIR2DL2 (killer cell immunoglobulin-like receptor, two Ig domains and long cytoplasmic tail 2) is a membrane-bound protein found primarily on natural killer (NK) cells. The canonical protein consists of 348 amino acid residues with a molecular mass of 38.5 kDa . It functions as an inhibitory receptor that recognizes specific HLA-C allotypes (specifically HLA-Cw1, 3, 7, and 8) . KIR2DL2 belongs to the immunoglobulin protein superfamily and undergoes post-translational modifications, most notably glycosylation . It has several synonyms in the literature including CD158b, NKAT-6, NKAT6, p58.2, and CD158B1 .

Recent research has revealed that KIR2DL2 plays a more complex role than previously thought, enhancing both protective and detrimental HLA class I-restricted anti-viral immunity in infections such as hepatitis C virus (HCV) and human T lymphotropic virus type 1 (HTLV-1) .

How can I distinguish between KIR2DL2, KIR2DL3, and KIR2DS2 in my experiments?

Distinguishing between these highly homologous KIR molecules presents a significant challenge for researchers. Most available antibodies cross-react with multiple KIR proteins. For example:

• Antibody clones CH-L, DX27, and GL-183 detect KIR2DS2 but also bind to KIR2DL2 and KIR2DL3

• Clone 1F12 distinguishes KIR2DS2 from KIR2DL2 but still binds KIR2DL3, limiting its use to donors with KIR2DL2/KIR2DS2 homozygous genotypes who lack KIR2DL3

A novel approach uses a combination of antibody clones CH-L and REA147. The CH-L clone binds to KIR2DL2, KIR2DL3, and KIR2DS2, while REA147 binds only to KIR2DL2 and KIR2DL3 but not KIR2DS2 . This combination allows identification of NK cells with relatively high KIR2DS2 expression (CH-L positive, REA147 negative) .

What are the recommended applications and dilutions for KIR2DL2 antibodies?

The optimal applications and dilutions depend on the specific antibody. For example, the Proteintech Rabbit Polyclonal KIR2DL2 antibody (31930-1-AP) has been validated for Western Blot and ELISA applications with human samples .

For Western Blot applications, the recommended dilution range is 1:500-1:2000 . Flow cytometry is also a widely used application for KIR2DL2 antibodies, as reported in over 200 citations in the literature .

How does KIR2DL2 influence the outcome of viral infections?

Research has revealed that KIR2DL2 enhances both protective and detrimental HLA class I-restricted immune responses. In HCV infection, KIR2DL2 enhances the protective effect of HLA-B*57 on both spontaneous viral clearance and viral load control in chronic carriers . A progressive effect with KIR2DL2 copy number was observed, consistent with reports linking KIR gene copy number to the frequency of cell-surface expression .

The odds ratio (OR) for spontaneous clearance vs. chronic infection in HLA-B*57 carriers showed:

• Without KIR2DL2: OR = 0.832 (p = 0.6)

• With KIR2DL2: OR = 0.403 (p = 0.007)

• With KIR2DL2 homozygosity: OR = 0.209 (p = 0.02)

(Note: OR < 1 indicates protection against chronic infection)

In HTLV-1 infection, KIR2DL2 similarly enhanced both protective and detrimental effects of different HLA alleles on disease status and proviral load .

What evidence supports KIR2DL2's role in T cell-mediated adaptive immunity?

While KIRs are traditionally associated with innate immunity, several lines of evidence suggest KIR2DL2 enhances HLA class I-restricted CD8+ T cell-mediated adaptive immunity:

• KIR2DL2 enhanced the protective effect of HBZ viral peptide binding by multiple HLA-A and B molecules. Since KIR2DL2 is not known to directly bind most HLA-A or -B molecules, this suggests an indirect mechanism involving T cells rather than direct NK cell recognition .

• Studies have shown that inhibitory KIRs on CD8+ T cells promote the survival of memory phenotype CD8+ T cells (Tm1) with enhanced cytolytic potential by reducing activation-induced cell death .

• In chronic viral infections including HTLV-1 and HCV, Tm1 cells constitute a minority of virus-specific CD8+ T cells but the majority of perforin-bright cells .

The proposed mechanism suggests that during chronic antigen stimulation, T cells carrying KIR2DL2 survive longer and therefore exert stronger effects—whether protective or detrimental depending on the HLA context .

How can I detect KIR2DS2-specific NK cell activation in primary human samples?

Recent research has identified a method to study KIR2DS2-specific activation in primary human samples:

• Use the antibody combination of CH-L and REA147 to identify KIR2DS2high NK cells (CH-L positive, REA147 negative) .

• This cell population can be used to assess NK cell degranulation in response to KIR2DS2-specific ligands, such as the viral helicase peptides LNPSVAATL (LNP) from hepatitis C virus and IVDLMCHATF (IVD) from dengue virus .

• In experimental validation, KIR2DS2high NK cells showed significant degranulation responses to these peptides, while KIR2DL3/L2high NK cells showed no significant response .

• For a negative control, KIR2DL3-positive NK cells from KIR2DL3 homozygous donors (lacking KIR2DS2) showed no significant changes in degranulation in response to the same peptides .

This methodology provides a valuable tool for investigating KIR2DS2 function in donors with the KIR2DL3/L2/S2 genotype, which has implications for cancer and viral infection research .

What controls should be included when studying KIR2DL2 in human samples?

When studying KIR2DL2 in human samples, several controls should be considered:

• Genotype controls: Include samples from individuals with known KIR genotypes, particularly:

  • KIR2DL2/KIR2DS2 homozygous donors (lacking KIR2DL3)

  • KIR2DL3 homozygous donors (lacking both KIR2DL2 and KIR2DS2)

• Antibody specificity controls: Use transfected cell lines expressing single KIR molecules to confirm antibody specificity. The studies mentioned used NKL cell lines transfected with KIR2DL2, KIR2DL3, or KIR2DS2 to validate antibody binding patterns .

• Functional controls: When assessing NK cell activation in response to specific ligands, include:

  • Peptide-negative controls

  • KIR-negative cell populations as internal controls

  • Donors lacking the specific KIR of interest

How does copy number variation of KIR2DL2 affect experimental outcomes?

Copy number variation (CNV) of KIR2DL2 has significant effects on experimental outcomes and should be considered in experimental design:

• A progressive effect with KIR2DL2 copy number has been observed on the enhancement of HLA-B*57-mediated protection against HCV. Individuals homozygous for KIR2DL2 showed stronger protection (OR = 0.209) compared to heterozygotes (OR = 0.475) .

• This progressive effect is consistent with reports linking KIR gene copy number to the frequency of cell-surface expression of the respective KIR molecule .

• When designing experiments, researchers should consider genotyping subjects for KIR2DL2 and determining zygosity to account for this variable.

• Data interpretation should include stratification by KIR2DL2 copy number to avoid missing significant associations that may be diluted in unstratified analyses .

How can I resolve cross-reactivity issues when studying KIR molecules?

Cross-reactivity presents a significant challenge in KIR research due to high sequence homology. Several approaches can help resolve these issues:

• Use antibody combinations: As demonstrated in recent research, combinations like CH-L and REA147 can distinguish KIR2DS2high from KIR2DL2/L3high NK cells .

• Validate with transfected cell lines: Create or obtain cell lines expressing single KIR molecules to validate antibody specificity before working with primary samples .

• Genetic approach: When possible, combine antibody-based detection with genetic KIR typing to confirm the presence or absence of specific KIR genes .

• Functional validation: Confirm antibody specificity through functional assays. For example, the KIR2DS2high population identified by the CH-L+/REA147- phenotype responded to KIR2DS2-specific peptide ligands, validating this approach .

How should I interpret conflicting data regarding KIR2DL2's role in disease?

When interpreting conflicting data about KIR2DL2's role in disease:

• Consider HLA context: The effect of KIR2DL2 is entirely context-dependent. It enhances both protective and detrimental effects of HLA alleles—if an HLA molecule is protective, KIR2DL2 enhances protection; if detrimental, KIR2DL2 enhances susceptibility .

• Stratify by KIR2DL2: Analyze data separately for KIR2DL2+ and KIR2DL2- subjects. Some associations only become apparent after stratification, as shown in the HTLV-1 study where C*08's protective effect on proviral load in HAM/TSP patients was only observed after stratifying by KIR2DL2 .

• Consider disease stage: KIR2DL2's effects may differ between disease stages. For example, in HCV, KIR2DL2 enhanced B*57's protection against both chronic infection establishment and viral control within established chronic infection .

• Evaluate both innate and adaptive mechanisms: While KIRs are traditionally associated with NK cells, evidence suggests KIR2DL2 also impacts T cell function, potentially explaining some conflicting observations .