Evidence of a second polymorphic ELA class I (ELA-B) locus and gene order for three loci of the equine major histocompatibility complex.

The research article explores the discovery of a second polymorphic ELA class I (ELA-B) locus and determines the gene order for three loci of the equine major histocompatibility complex. Their studies indicate that the antibodies produced by these antisera recognize the products of genes linked to the ELA system.

Immunization and Antisera Production

• The researchers made use of two antisera, called B-442 and R-2046. These were produced by immunizing an offspring using purified peripheral blood lymphocytes from a parent that matched for ELA-A specificity.
• Absorption analysis revealed that these antisera contained two types of cytotoxic antibodies: one targeted antigens present on T and B cells, and the other was more directed against antigens on surface Ig positive cells.

Immunoprecipitation Studies

• Immunoprecipitation studies were conducted using the previously mentioned antisera. Both antisera were observed to have antibodies specific for glycoproteins that share similar molecular weights with class I and class II MHC antigens.
• In tests that were conducted with unfractionated lymphocytes, only the class I activity was easily detectable, while the class II activity resulted in less than 25% cell death.

Linkage to the ELA System

• Further family studies showed that the antisera recognize the products of genes connected to the ELA system.
• The specificities detected by B-442 and R-2046 are not products of the ELA-A locus per their findings. Instead, these appear to be products of a different locus, which the researchers define in the paper as ELA-B.

Determining Gene Order

• Through studying two recombinants in a large family, evidence emerged that supports the presence of the ELA-B locus.
• Additionally, within this family, a third recombinant was identified between the A blood group system and the ELA-A locus.
• Based on these three recombinants, the most probable linear relationship of the genes is determined to be A blood group system, ELA-A, and ELA-B in that order.