Monoclonal antibodies specific for apoproteins of lipophorins from the migratory locust

Spleen lymphocytes from mice immunized with locust native low-density lipophorin A⁺ (LDLp) were fused with nonproducing myeloma cells, strain Sp 2/0. Hybridomas that were isolated from the fused cells produced antibodies specific for LDLp and the high-density lipophorin A_yellow (HDLp). Monoclonal strains were generated through cloning by limiting dilution from those hybridomas synthesizing antibodies specific for apolipophorins (apoLp)-I, -II, and -III of LDLp. Additionally, a hybridoma strain that was obtained after fusion of lymphocytes from mice immunized with apoLp-III produced antibodies that bind to apoLp-III and native LDLp. Some features of LDLp and HDLp were studied using these antibodies. It could be demonstrated that apoLp-I and apoLp-II are not immunochemically identical and are exposed in the native particle of both LDLp and HDLp. It was also shown that in both lipophorins apoLp-II is less exposed than apoLp-I, whereas in LDLp apoLp-III is mainly exposed; some apoLp-III could also be detected in HDLp. Tween-20, a nonionic detergent, appears to affect the binding of anti-apoLp-I, -II, and -III to both LDLp and HDLp. The monoclonal antibodies specific for locust apolipophorins do not bind to the respective apoproteins of lipophorins from other insects.