ULTRASTRUCTURAL, HISTOCHEMICAL AND IMMUNOHISTOCHEMICAL FEATURES OF PORCINE INTESTINAL LAMINA PROPRIA MACROPHAGES, PERIPHERAL-BLOOD MONOCYTES AND SPLENIC ADHERENT CELLS

Ultrastructural, histochemical and immunohistochemical features of por cine intestinal lamina propria macrophages (LPMs), peripheral blood fi bronectin-adherent cells (FACs) and splenic-adherent cells (SPACs) wer e compared. Freshly isolated FACs and SPACs were small and showed smal l cytoplasmic processes, little evidence of endocytic vacuoles, few ly sosomes and sparse rough endoplasmic reticulum (RER). Fresh FACs were negative for acid phosphatase, non-specific esterase (NSE) and beta-ga lactosidase activity. Of the SPACs, 20-40%. were positive for acid pho sphatase, <5% for NSE and 5-10% for beta-galactosidase. Pre-cultured F ACs and SPACs were large and showed an abundance crf endocytic vacuole s; they possessed dilated and prominent RER and >95% were positive for the three enzyme activities. LPMs exhibited abundant endocytic vacuol es or vesicles and lysosomes but sparse RER, and >85% were positive fo r the three enzymes. LPMs (24%), FACs (49%) and SPACs (40%) expressed MHC (major histocompatibility complex) class II glycoproteins. Macroph age granulocyte antigens were detected in LPMs (14%), FACs (50%) and S PACs (33%). The results thus suggest that freshly isolated FACs differ from LPMs morphologically and in enzymic features, and the difference s may represent part of the cell maturation process.