Combining Site Specificities Research Articles

Heterogeneity in combining site specificity of anti-hapten antibodies produced in response to a panosyl-azoprotein conjugate.

AbstractPanose (O‐α‐D‐glucosyl‐(1→6)‐O‐α‐D‐glucosyl‐(1→4)‐α‐D‐glucose) and maltose (O‐α‐D‐glucosyl‐(1→4)‐α‐D‐glucose) coupled to bovine serum albumin (BSA) by means of an azophenyl linkage provided the synthetic antigens panosyl‐BSA and maltosyl‐BSA, used to examine the anti‐hapten specificity of rabbit sera prepared against panosyl‐BSA.The combining site specificity of cross‐reactive antibodies in carrier‐absorbed anti‐panoside sera was investigated by quantitative hapten inhibition of maltosyl BSA‐anti‐panoside cross‐precipitation and compared with data obtained by inhibition of homologous precipitation.Immunochemical data obtained demonstrate a heterogeneity in the combining site specificity of anti‐hapten produced in response to panosyl‐BSA and establish the occurrence of at least two distinct kinds of antibody directed against the α‐(1→6)‐α‐(1→4) sequence of glucose units. One type of anti‐panoside, inhibited more effectively by isomaltose than by maltose, shows isomaltose end group immunodominance. A second type of anti‐panoside, cross‐precipitated by maltosyl‐BSA and more effectively inhibited by maltose than by isomaltose, shows maltose immunodominance.

The Clonal Nature of Antibody Formation

Abstract Antibody cell clones of (C57BL/6 C3H/HeJ) F1 mice directed against the haptens, poly-O-acetyl-d-serine (poly-ser) and poly-d-alanine (poly-ala), were evaluated with the aid of a cell transfer system and a modified plaque assay. When antibody responses to poly-ser or poly-ala were initiated by a few precursor cells, unequal associations of a given antibody specificity with one of two parental antibody allotypes became apparent: namely, poly-ser specific clones of C3H/HeJ allotype were more frequent than those of C57BL/6 allotype, whereas poly-ala specific clones of C57BL/6 allotype were more frequent than those of C3H/HeJ allotype. The degree of these unequal associations could be accentuated when both poly-ser and poly-ala specific clones were induced with proteins bearing random copolymers of O-acetyl-d-serine and d-alanine (ser-ala). In this instance the proportion of clones which were of C57BL/6 allotype was greater than that obtained with either homopolymer hapten. We interpreted these results as consistent with the following: 1) that closely-linked genes encoded for the two distinct portions of mouse immunoglobulin heavy-chain that determine allotype (constant region) and combining site specificity (variable region); and 2) that more of the immunoglobulin structural genes of the C3H/HeJ allelic chromosomal region could encode for antibodies to the poly-ser hapten than those of the C57BL/6 allelic chromosomal region, while the converse seemed true for antibodies specific to the poly-ala hapten.