Table 1: Summary of Blood Group Systems Associated with "HTLA" Antibodies

This table summarizes essential points of each blood group system. There is a printable resource found at the bottom of the page.

Blood Group System	Antigens	Key Characteristics	Clinically Significant	Enzyme Treatment (e.g., papain, ficin)	Disulfide Bond-Reducing Agents (e.g., DTT)	Trypsin and Alpha-Chymotrypsin	Complement Activation
Chido and Rodgers (ISBT 017)	9 antigens: Chido - Ch1, Ch2, Ch3, Ch4, Ch5, Ch6 Rodgers - Rg1 and Rg2 WH	Located on complement component C4 protein: Ch found on C4b; Lack C4b (Ch-) are more susceptible to bacterial meningitis Rg found on C4a; Lack C4a (Rg-) are more susceptible to SLE	No Perform neutralization (add equal amounts pooled normal plasma to plasma with antibody) to remove interference with testing	Sensitive	Resistant	Sensitive	No
JMH (ISBT 026)	6 antigens	Called "Old Man Antibody" - commonly found in older males	No known disease associations	Sensitive	Sensitive	Sensitive	No - naturally occurring; IgG4 subclass
Knops (ISBT 022)	9 antigens: Kna and Knb, McCa and McCb, SIa, SI3, Yka, KCAM, and Vil	Kna, McCa, SIa, Yka, and KCAM are found in >90% of population; most common to interfere with serological testing	No	Resistant	Sensitive	Sensitive	No
COST (ISBT 205)	2 main antigens: Csa and Csb	Considered a collection of antigens and not blood group system Csa found in 98% of population Csb found in 35% of population	No	Resistant	Resistant	Resistant	No - IgG class, specifically IgG1 and IgG3
Cartwright (ISBT 011)	Yta and Ytb	Yta on 99.8% of red cells; mimics "HTLA", not true "HTLA" Ytb on <1% of red cells	Yes - recommended to perform MMA* prior to transfusion to determine level of risk	Variable	Sensitive	Variable	No - IgG class, specifically IgG1 and IgG3
Dombrock (ISBT 014)	10 antigens: Antithetical - Doa and Dob 8 are high-prevalence - Gya, Hy, Joa, DOYA, DOMR, DOLG, DOLC, and DODE	Doa and Dob can be found in sera of patients that have produced other alloantibodies Weak and variable reactivity leading to false negative results in serological testing; molecular testing needed	Yes - severe HTRs	Resistant	Sensitive	Sensitive	No - IgG, specifically IgG1 and IgG3
Gerbich (ISBT 020)	5 high-prevalence antigens: Ge2, Ge3, GEPL, GEAT, and GETI 5 low-prevalence antigens: Wb, Lsa, Ana, Dha, and GEIS	2 antibodies that are confused with "HTLA" antibodies: anti-Ge2 and anti-Ge3	Anti-Ge2 is not clinically significant Anti-Ge3 is clinically significant, linked with HTRs and HDFN - recommended to perform MMA* prior to transfusion to determine level of risk	Sensitive (Ge2) Resistant (Ge3)	Resistant	Sensitive (Ge2) Resistant (Ge3)	Yes, both Ge2 and Ge3 bind complement
Lutheran (ISBT 005)	25 antigens Most relevant: Lua is low prevalence Lub is high prevalence	Display dosage Agglutination is loose, stringy or mixed field-like Lutheran null phenotype - Lu(a-b-) can produce anti-Lu3	Yes - delayed and acute HTRs Lutheran are not a cause of HDFN as they are not well developed at birth	Resistant	Sensitive	Sensitive	Lua - no; naturally occurring, mixture of IgM, IgG, and IgA Lub - no; IgG class, specifically IgG1 and IgG3
VEL (ISBT 034)	Vel	High-prevalence Weak expression on cord blood	Yes - HTRs and HDFN	Resistant	Variable	Resistant	Yes - mixture of IgM and IgG; can incubate at room temp; mostly demonstrated at AHG

*MMA = Monocyte Monolayer Assay; it predicts the likelihood of a hemolytic reaction after transfusion with crossmatch incompatible blood and is often used when rare antigen-negative blood is not readily available. Further information can be found on page 29 of this course.