Аннотация:One of the most important peculiarities of viruses is their ability to mimic the natural biologically active ligands influencing proliferation of target cells. Three groups of peptides from separate regions of HIV proteins gp120 and gp41 were studied, including peptides homologous to HLA class II, linear peptides modified by multiplet fragments of proteins responsible for contact interaction, and multiplet forms of these fragments. The following fragments were used: RGDS, the adhesive part of extracellular matrix protein; RFDS, a peptide of HLA DR domain β1, and ForMLP peptide of chemotaxis. Human cell lines of different origin (T and B lymphocytes, as well as erythroblastoma K-562 cells) were used as test systems. The above-mentioned peptides are able to influence the proliferative activity of the cells. The presence of unmodified peptides homologous to those of class II HLA and of linear modified peptides able to contact with the CD4 coreceptor results in an enhanced proliferative response of the T cell line MOLT-4. Unmodified peptides homologous to class II HLA are able to interact with B cells IM-9 and CESS, as well as with nonlymphoid cells K-562 and stimulate their growth. Multiplet forms of RGDS and RFDS exhibit a specific effect on migration of different cell types. Cell activation by these peptides is mediated by their interaction with the integrin-type membrane structures which are specific for each cell subpopulation.