Background: The immune system can elicit antibodies against a wide var
iety of antigens. We have proposed that crystal surfaces may also oper
ate as antigens, binding specific antibodies. Here we exploit the crys
tal surfaces of cholesterol monohydrate to investigate antibody-surfac
e recognition at the molecular level. Results: Four monoclonal antibod
ies were selected. Two specifically interact with cholesterol monohydr
ate crystals, and one with 1,4-dinitrobenzene crystals. The fourth int
eracts nonselectively with various solid substrates. The relative reac
tivities of the four antibodies to the different surfaces of cholester
ol monohydrate and to other surfaces were compared. The nonspecific an
tibody adsorbs mainly at imperfections. Of the two specific antibodies
, one shows a clear preference for one set of faces, relative to other
s, the second adsorbs selectively at one face of cholesterol monohydra
te crystals. Conclusions: Monoclonal antibodies can be selected that s
pecifically bind to the crystal surfaces of cholesterol monohydrate. T
he binding sites of such antibodies appear to recognize a number of mo
lecular moieties, exposed at the surface in a specific structural orga
nization. Different antibodies recognize different structural organiza
tions with varying degrees of selectivity. Antibody-crystal surface in
teractions may serve as convenient models for studies aimed at an unde
rstanding of the molecular bases of antibody recognition.