ANALYSIS OF V-H GENES REARRANGED BY INDIVIDUAL B-CELLS IN DERMAL INFILTRATES OF PATIENTS WITH MYCOSIS-FUNGOIDES

In patients with cutaneous T cell lymphomas such as mycosis fungoides B cells can frequently be detected in the lymphocytic dermal infiltrat e. To analyse their immunoglobulin heavy chain gene repertoire, single B cells were obtained from tissue sections of two typical patients wi th mycosis fungoides using hydraulic micromanipulation followed by spe cific amplification of the respective gene segments by single-cell pol ymerase chain reaction (PCR) technique. A total of 21 V(H)DJ(H) genes was sequenced. From each individual B cell a single productive V(H)DJ( H) rearrangement was obtained. There was no clonal relationship detect ed between any of these rearrangements suggesting polyclonality of the infiltrating B cells. The representation of V-H families was in accor dance with the germ-line complexity. A remarkably high number of V-H g enes (5/13 in patient 1; 3/8 in patient 2) was completely or nearly ge rm-line-identical Five of seven V(H)4 family genes were nearly unmutat ed. On the other hand, most of the V(H)3 gene family members were soma tically mutated in an antigen-driven manner. The proportion of germ-li ne-identical V-H genes, the usage of individual V-H, D, J(H) gene elem ents, and the pattern of somatic mutations found in the B cells infilt rating skin lesions of patients with mycosis fungoides resembles the p eripheral blood repertoire, suggesting a bystander role of these cells .