GROWTH AND DIFFERENTIATION INVITRO OF MAST-CELLS FROM MESENTERIC LYMPH-NODES OF NIPPOSTRONGYLUS-BRASILIENSIS-INFECTED RATS

Abstract

Intestinal mastocytosis begins to develop in rats, depending on the strain, at 14 (outbred Sprague-Dawley, SD) or 16 (inbred Lewis, L) days after infection with the nematode N. brasiliensis (Nippo). In vitro mastopoiesis from mesenteric lymph node (MLN) cells cultured at various intervals post-infection was investigated, using a modified Marbrook liquid system. Greater increases in mast cells (MC) were observed in cultures of SD-MLN removed on day 14 after Nippo infection (IMLN-14) than from MLN removed from uninfected animals (NMLN): 7- to 20-fold vs. up to 2-fold at 2 wk and 40 to 200-fold vs. up to 20-fold at 4 wk, respectively (P < 0.002). Similar differential increases in MC and histamine compared to uninfested controls were demonstrated in 2 week cultures of MLN from L strain rats removed 17 (IMLN-17) and 20 (IMLN-20) but not 14 days after Nippo infection (P < 0.001). The presence of phytohemagglutinin (PHA) in vitro was associated with enhanced MC differentiation from IMLN-17 and IMLN-20; worm antigen (Ag) stimulated mastopoiesis from IMLN-17 but suppressed the response from IMLN-20 (P < 0.02). Conditioned media (CM) prepared from unstimulated or PHA-stimulated IMLN-32 (i.e., removed 32 days after Nippo infection) caused significant mastopoiesis from NMLN in vitro when compared to no CM or Ag-stimulated CM (P < 0.01). MC precursors or cells which help MC differentiation exist in increased numbers in MLN of Nippo-infected rats. Mitogenic or antigenic stimulation modulates in vitro mastopoiesis, directly or through soluble factors derivable from MLN cells. These in vitro methods can be used to understand further mechanisms of intestinal mastocytosis in the rat.