HLA antibodies cytotoxic only for B lymphocytes

Area of Science:

• Immunology
• Serology
• Transfusion Medicine

Background:

• Identifying specific antibodies in patient sera is crucial for transfusion compatibility and understanding immune responses.
• Previous studies have focused on antibodies reacting with lymphocytes, but specificity against B cell subsets requires further investigation.

Purpose of the Study:

• To characterize antibodies in sera from polytransfused individuals and multiparous women that react with B cell-enriched suspensions.
• To determine the specificity of these antibodies, distinguishing between true anti-B cell antibodies and those with broader reactivity.

Main Methods:

• Sera from 28 individuals were tested for cytotoxicity against peripheral blood lymphocytes.
• Positive reactions against B cell-enriched suspensions were further analyzed using platelet absorption-elution and pretreatment with anti-beta2-microglobulin serum.
• Absorption experiments with purified T and B lymphocytes were conducted to assess antibody specificity.

Main Results:

• Of 13 sera reacting with B cells, five showed pure anti-B cell reactivity.
• Four sera contained antibodies against both B cell determinants and HLA-A, -B, or -C antigens.
• Four sera contained antibodies solely against HLA-A, -B, or -C specificities, and these could be absorbed by T cells despite non-cytotoxicity.

Conclusions:

• Antibodies reacting with B lymphocytes do not always target B-cell specificities; some cross-react with T cell determinants.
• Exhaustive absorption with platelets is essential before classifying sera as anti-B cell-specific reagents to ensure accuracy.