Serologic identification of the human secondary B cell antigens. Correlations between function, genetics, and...

Area of Science:

• Immunogenetics
• Molecular Immunology
• Human Leukocyte Antigen (HLA) System

Background:

• Secondary B cell (SB) antigens are polymorphic, HLA-linked determinants found on B cells and macrophages.
• These antigens are recognized by primed T cells and are genetically distinct from HLA-DR, MB, and MT antigens.

Purpose of the Study:

• To serologically identify the SB molecule using the monoclonal antibody ILR1.
• To correlate SB antigen function in T cell recognition with molecular structure and genetic location.
• To characterize the genetic locus of SB antigens within the HLA system.

Main Methods:

• Utilized the monoclonal antibody ILR1 for serologic identification of SB antigens.
• Assessed T cell proliferative responses to SB2 and SB3 antigens.
• Examined ILR1 reactivity in a panel of HLA-deletion mutant lymphoblastoid cell lines.

Main Results:

• The ILR1 antibody specifically identifies an epitope on certain SB gene alleles.
• ILR1 reactivity correlated with SB2 and SB3 polymorphism and inhibited T cell responses.
• Serologic studies revealed two HLA regions centromeric to HLA-B controlling Ia-like molecule expression, including SB antigens.

Conclusions:

• SB antigens are associated with Ia-like molecules, indicating their role in immune recognition.
• The genetic locus for SB antigens represents a new HLA subregion.
• These findings provide a molecular and genetic basis for understanding SB antigen function in T cell responses.